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Abstract

The objective of this study was to (1) to determine the contribution of moderate sun bed exposure to serum 25(OH)D(3) levels; (2) to estimate the decay time of a high 25(OH)D(3) level obtained by sun bed exposure; and (3) to evaluate if the recommended ingestion of vitamin D is sufficient to maintain the 25(OH)D(3) concentration obtained by sun bed exposure. Ten volunteers (20-35 y.o.), skin type I and II, living in Olso, Norway were whole body exposed twice per week to the radiation of a commercial and approved sun bed (Life Sun S 100 W, Wolff System), starting with 0.5 MED (minimal erythema dose) and escalating to up to 1 MED per exposure for 4 weeks. After that, half of the volunteers were given a daily supplement of 200 IU vitamin D in the form of cod liver oil capsules, while the other half of the persons received no supplements. Erythema did not occur at any time and a slight pigmentation was seen in most of the volunteers after the sun bed exposures. Serum level of 25(OH)D(3) increased by about 40% on the average. The initial serum 25(OH)D(3) level was different among the volunteers (40-100 nmol/L). Within eight weeks after the last exposure the 25(OH)D(3) level decreased to the initial value in all volunteers irrespective of vitamin D supplementation or not.

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... The spectrum of two sun beds, the one used in the present work and that used in our earlier work (30), compared with the solar spectrum at noon, midsummer in Oslo and under the Equator, are shown in Fig. 1. General characteristics of the study population are given in Table 1. ...
... The sun bed UVB fluence rates were larger in our earlier study (30) than in the present one, but none of them are widely different from that in Equatorial sun. However, the UVA fluence rates are larger for the sun beds, notably for the one used in the present work. ...
... However, as Fig. 2 shows, there is almost a linear increase up to the last exposure, so complete saturation did probably not occur. This is in contrast to our earlier work (30) which indicated that saturation might be approached 5 already after 4 weeks. However, another type of sun bed-one emitting more UVB-was used in the first study, which included only 10 persons. ...
Article
The objectives of this work were: (1) To determine whether repeated exposures to small doses from a commercial sun bed (Wolff Solarium Super Plus 100 W) over 5 weeks gave less vitamin D than repeated exposures to twice as large, but still nonerythemogenic, doses. (2) To investigate whether the contribution to the vitamin D status from such sessions of exposures was dependent on the baseline status before the start of the sessions. (3) To determine the decay rate of the induced increment of vitamin D. The sun bed sessions raised the 25-hydroxyvitamin D levels from typical winter values to typical summer values. The mean value after exposure being 80 nm (+/-14) and the increase being 15 nm on average. Persons with the lowest initial levels got the largest increase. The level in this group was back to the pre-exposure level after 2-4 weeks. To maintain a summer level through the winter, when no vitamin D is produced by the sun in northern countries, one should consider increasing the recommended intake of vitamin D intake significantly, or encouraging the population to get moderate, nonerythemal sun bed exposures.
... This is reflected by a clear seasonal variation in vitamin D status [1]. Therefore, many persons, especially at higher latitudes during winter, make use of different ultraviolet (UV) sources (broad-band and narrow-band UVB lamps, solar simulators and sunbeds) to increase their vitamin D levels [2][3][4][5][6][7][8]. Any standard commercial or therapeutic UVB sources, such as those used for treatment of psoriasis, are able to increase the levels of serum 25-hydroxyvitamin D (25(OH)D), the marker for vitamin D status [2][3][4][5][6][7][8]. ...
... Therefore, many persons, especially at higher latitudes during winter, make use of different ultraviolet (UV) sources (broad-band and narrow-band UVB lamps, solar simulators and sunbeds) to increase their vitamin D levels [2][3][4][5][6][7][8]. Any standard commercial or therapeutic UVB sources, such as those used for treatment of psoriasis, are able to increase the levels of serum 25-hydroxyvitamin D (25(OH)D), the marker for vitamin D status [2][3][4][5][6][7][8]. ...
... Their mean baseline serum 25(OH)D concentration was 61.6 nmol/l (Table I), similar to that found in a recent study in Swedish women [25]. Scandinavians have generally higher 25(OH)D levels than persons in southern Europe [26][27][28], probably due to regular intake of cod liver supplements and fatty fish [29]; however, cutaneous vitamin D synthesis seems to be a major contributor to vitamin D status, even at northern latitudes [25], and in agreement with previous study results [2][3][4][5][6][7][8], we found that artificial UV sources are efficient in raising 25(OH)D levels (Figure 3(a)). ...
Article
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Aims: Ultraviolet (UV) radiation is a major source for vitamin D production. Furthermore, UV destroys cobalamins (also called vitamin B12) in solution. However, data from humans are scarce. The aim of the present study was to clarify if UV exposure has any effect on serum cobalamins, as compared to vitamin D levels, in healthy volunteers. Methods: This single-center, open observational study was conducted in a research institute: 23 non-pregnant, non-lactating, healthy, fair-skinned female subjects had their serum cobalamin and 25-hydroxyvitamin D (25(OH)D, the marker for vitamin D status) levels measured before and after exposure to UV. Results: UV exposure increased serum 25(OH)D levels from 61.6 nmol/L to 88.5 nmol/L (44%; p < 0.001). A statistically insignificant decay in serum cobalamin levels from 300 pmol/L to 260 pmol/L (13%; p = 0.142) was observed in the volunteers after the first UV exposure; however, no additional decline of statistical significance was seen after subsequent exposures. Conclusions: Multiple exposure to UV radiation give a significant increase in 25(OH)D levels, but has no detrimental effect on cobalamin concentrations. © 2015 the Nordic Societies of Public Health.
... Finally, sunbeds are efficient in producing vitamin D, even in completely non-erythemogenic doses [78][79][80]. Ten-20-minutes whole-body irradiance in a sunbed with 2%-5% UVB of total UV can generate 10,000-15,000 IU of vitamin D [78,81]. A food intake of the recommended dose of vitamin D in Norway when the study was carried out, was too little to keep a summer level in the winter [78]. ...
... Finally, sunbeds are efficient in producing vitamin D, even in completely non-erythemogenic doses [78][79][80]. Ten-20-minutes whole-body irradiance in a sunbed with 2%-5% UVB of total UV can generate 10,000-15,000 IU of vitamin D [78,81]. A food intake of the recommended dose of vitamin D in Norway when the study was carried out, was too little to keep a summer level in the winter [78]. ...
... Ten-20-minutes whole-body irradiance in a sunbed with 2%-5% UVB of total UV can generate 10,000-15,000 IU of vitamin D [78,81]. A food intake of the recommended dose of vitamin D in Norway when the study was carried out, was too little to keep a summer level in the winter [78]. Although the International Agency for Research on Cancer claimed that sunbed use increases the risk of melanoma [82], this study is flawed in that it included several studies from the United Kingdom that did not consider the effect of skin pigmentation and increased genetic risk for melanoma. ...
Article
A low serum 25-hydroxyvitamin D [25(OH)D] level is a risk factor for many diseases, including musculoskeletal diseases, many types of cancer, cardiovascular diseases, diabetes mellitus, infectious diseases, autoimmune diseases, and brain diseases. This report estimates the reduction in mortality rates for the five Nordic countries for an increase in population mean serum 25-hydroxyvitamin D level to 105 nmol/L. Serum vitamin D dose-incidence/prognosis relationships can be developed with significant levels of reliability for most vitamin D-sensitive diseases on the basis of ecological, cross-sectional, and observational studies, randomized controlled trials, and meta-analysis of such studies. These dose-response relations are used to estimate the population-wide benefit of raising mean serum 25(OH)D concentration to 105 nmol/L for the five Nordic countries. From this study, the reductions in mortality rates possible by raising population mean serum 25(OH)D levels to 105 nmol/L are: Denmark, 17% (estimated range,11%-24%); Finland, 24% (17%-32%); Iceland, 24% (17%-32%); Norway, 18% (11%-26%); and Sweden, 18% (8%-25%). Reaching these levels would require changes in health policies with respect to solar ultraviolet-B (UVB) irradiance, vitamin D fortification of food, availability of vitamin D and calcium supplements, and attitude toward use of UVB lamps. Adverse effects of oral vitamin D intake are limited, and those from UVB irradiance are minor compared with the benefits.
... In vivo studies of the relationship between solar UV exposure and serum 25(OH)D in humans have been carried out using simulated sunlight from sun beds (15), by measuring personal sun exposure using UVR dosimeters (16), and by obtaining self-reports of sun exposure using questionnaires (17). Our study aimed to address the quantitative relationship between personal solar UV exposure and serum 25(OH)D in healthy subjects in South Australia using a validated approach to obtaining recall of personal sun exposure and routine ambient solar UV measurements. ...
... A Norwegian study performed between October and March when there is no solar UV induced vitamin D synthesis, used sun beds as a UV source (measured fluence 12 mW cm )2 UVA and 0.48 W cm )2 UVB). Ten men and women aged 23-35 years were given 10 whole body sunbed exposures escalating over 4 weeks from 0.5 MED to a maximum of 1 MED (15). A plateau in mean serum 25(OH)D at 92 nmol L )1 was reached after 3 weeks of exposure (15). ...
... Ten men and women aged 23-35 years were given 10 whole body sunbed exposures escalating over 4 weeks from 0.5 MED to a maximum of 1 MED (15). A plateau in mean serum 25(OH)D at 92 nmol L )1 was reached after 3 weeks of exposure (15). Daily oral doses of 200 IU of vitamin D per day for 2 weeks after sun-bed exposure ceased did not increase the average plateau level of 25(OH)D in five subjects (15). ...
Article
Solar ultraviolet-B radiation (UVB) is essential for epidermal vitamin D production. We aimed to quantitate the relationship between personal solar UV exposure and serum 25hydroxy vitamin D (25[OH]D) concentration. Blood was collected for 25(OH)D analysis in 207 South Australian adults aged 27-61 years. At the time of blood collection, each participant completed a questionnaire, which included a calendar for recall of sun exposure in the preceding 16 weeks. We examined the association between solar UV exposure and serum 25(OH)D graphically from smoothed scatter plots, and modeled it using multiple linear regression, with age, sex and body mass index as covariates. Estimated erythemal solar UV exposure in the 6 weeks before blood collection best predicted serum 25(OH)D concentrations. Serum 25(OH)D rose with increasing personal solar UV exposure to a maximum of about 89 nmol L(-1) at an estimated mean weekly solar erythemal UV exposure of about 1230 mJ cm(-2) . The maximum was the same after accounting for clothing coverage and was reached at an estimated whole body equivalent exposure to ambient UV of ca 700 mJ cm(-2) . These results suggest that an average maximum serum 25(OH)D of ca 89 nmol L(-1) is achieved from sun exposure in a healthy Australian adult population.
... b: Eight references (Ala-Houhala et al. 1988; Andersen et al. 2013; Hower et al. 2013; Lehtonen-Veromaa et al. 2008; Madsen et al. 2013; Rich-Edwards et al. 2011; Sullivan et al. 2005) provided data on populations which are considered as eight separate studies. c: Forty-nine references (Ala-Houhala et al. 1986 6 ; Barger-Lux et al. 1998; Barnes et al. 2006; Brazier et al. 2002; Bischoff et al. 2003; Bolton-Smith et al. 2007; Bonjour et al. 2013; Braam et al. 2003; Cashman et al. 2014; Cashman et al. 2008; Cashman et al. 2012; Cashman et al. 2009; Close et al. 2013; DeLappe et al. 2006; Forman et al. 2013; Goussous et al. 2005; De Gruijl et al. 2012; Hansen et al. 2010; Harris et al. 2002 7 ; Heaney et al. 2003; Heikkinen et al. 1998; Holick et al. 2008; Holm et al. 2008; Honkanen et al. 1990 8 ; Johnson et al. 2005; Keane et al. 1998; Larsen et al. 2012; Lehman et al. 2013; Madsen et al. 2013; Meier et al. 2004; Mocanu et al. 2009; Nelson et al. 2009; Patel et al. 2001 9 ; Pekkarinen et al. 2010; Porojnicu et al. 2008; Smith et al. 2009; Schmidt et al. 2011; Sorva et al. 1994; Trautvetter et al. 2014; Vieth et al. 2001; Viljakainen et al. 2006; Viljakainen et al. 2009; White et al. 2009; Wood et al. 2014 10 ; Andersen et al. 2013; Darling et al. 2013; MacDonald et al. 2011; Hill et al. 2005; Kift et al. 2013The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. ...
... The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the rights of the authors. 18 Pekkarinen et al. 2010; Porojnicu et al. 2008; Trautvetter et al. 2014; Vieth et al. 2001; Viljakainen et al. 2006). For two studies, 25(OH)D measurements were only measured once and not at baseline (Atas et al. 2013; Ala-Houhala et al. 1986). ...
... There was a large variation in trial duration, ranging from six weeks (Holick et al. 2008) to three years (Braam et al. 2003). Among the fifty included trials, 42 provided the participants with vitamin D supplements (AlaHouhala et al. 1986 34 ; Barger-Lux et al. 1998; Barnes et al. 2006; Brazier et al. 2002; Bischoff et al. 2003; Bolton-Smith et al. 2007; Braam et al. 2003; Cashman et al. 2014; Cashman et al. 2008; Cashman et al. 2012; Cashman et al. 2009; Close et al. 2013; DeLappe et al. 2006; Forman et al. 2013; Goussous et al. 2005; De Gruijl et al. 2012; Harris et al. 2002 35 ; Heaney et al. 2003; Heikkinen et al. 1998; Holick et al. 2008; Holm et al. 2008; Honkanen et al. 1990 36 ; Larsen et al. 2012; Lehman et al. 2013; Meier et al. 2004; Nelson et al. 2009; Patel et al. 2001 37 ; Pekkarinen et al. 2010; Porojnicu et al. 2008; Smith et al. 2009; Schmidt et al. 2011; Sorva et al. 1994; Vieth et al. 2001; Viljakainen et al. 2006; Viljakainen et al. 2009; Wood et al. 2014 38 ). In only two trials, a treatment arm with a vitamin D 2 supplement was included (Holick et al. 2008; Lehman et al. 2013), two trials treated participants with a supplement of vitamin D 2 and vitamin D 3 (Holick et al. 2008; Sorva et al. 1994), and two trials did not specify the form of vitamin D included in the supplement (Braam et al, 2003; Holm et al. 2008). ...
Article
In recent years, there has been much attention for the global high prevalence of low blood concentrations of 25(OH)D, as an indicator of vitamin D status. These 25(OH)D concentrations primarily depend upon the level of sun exposure. However, also dietary vitamin D intake is of importance, especially at higher latitudes during winter. To get insight in the amount of oral vitamin D needed to achieve and maintain an adequate 25(OH)D blood concentration, the aim of this review was to systematically investigate the intake-status relationship for vitamin D under minimal endogenous vitamin D synthesis, as preparatory work for the setting of Dietary Reference Values for vitamin D. Searches were conducted in Medline, Embase and Cochrane. All published prospective cohort studies with the vitamin D intake-status relationship as the primary aim of investigation, as well as all trials, issued through 23-7-2014 and covering all ages, were included in this review, which resulted in 7,807 unique hits. Subsequently, 1,323 potentially relevant articles were identified by title and abstract screening. Hand searches led to the inclusion of 22 additional potentially relevant papers. Thus, in total, 1,345 full-text papers were screened. After full text screening, 56 articles met the predefined inclusion criteria, resulting in the inclusion of 65 studies, i.e. 57 trials and 8 prospective cohort studies, in infants, children or adults (one article corresponding to one to three studies). Two of the included studies were conducted in infants, eight in children or adolescents, and 55 in adults. The majority of the studies examined the impact of vitamin D3. Most trials studies showed a dose-response relation between vitamin D intake and status. However, as the impact of a similar dose of vitamin D on 25(OH)D concentration substantially differed across the studies, it is difficult to quantify this dose-response relationship. Therefore, the exact nature of the vitamin D dose-response relationship warrants further investigation, for instance by performing meta-regression analyses.
... El uso de ácidos grasos poliinsaturados (PUFA) mejora los síntomas de las enfermedades de la piel; algunos han sido aprobados para uso clínico o están en ensayos clínicos para uso preventivo o terapéutico. (1) Si los supuestos de la teoría de los radicales libres del envejecimiento son ciertos, debería ser posible ralentizar el proceso de envejecimiento mediante la intervención en la velocidad de generación de especies reactivas de oxígeno y/o sus reacciones con macromoléculas vitales, mediante la administración de antioxidantes exógenos. Sin embargo, esta problemática ha sido poco abordada en las revisiones bibliográficas disponibles internacionalmente. ...
... El aceite de pescado contiene cantidades significativas de vitamina A, vitamina D, colesterol, monoglicéridos, diglicéridos, triglicéridos, ácidos grasos libres, fosfolípidos y esterilésteres. (1) Los ácidos grasos en el aceite de pescado pueden formar parte de los lípidos neutros o encontrarse en forma libre. La composición de estos se puede dividir en ácidos grasos saturados, ácidos grasos monoinsaturados y ácidos grasos de cadena pesada. ...
Article
Full-text available
Aging in general, and skin aging in particular, is a deleterious and universal process. Skin aging can be divided into chronological aging and photoaging, the latter being activated through damage to human skin, attributable to repeated exposure to ultraviolet (UV) rays from sunlight. Fatty acids derived from fish oil (omega 3) have been considered to be associated with photoprotection of the skin. The objective of this work is to describe the effects of omega 3 as an anti-aging drug in the elderly population. A bibliographic review of articles published between January 2010 and June 2020, in Pubmed and Google Scholar, was carried out. The available literature shows the effect and benefit of these fatty acids in the aging process, which constitute clinical therapies at the dermatological level and in areas of plastic surgery. Its use has a positive effect on the aging process in different organs, through action against oxidative stress.
... Most of tanning devices have fluorescent lamps with erythemal-effective radiant exposure H er (in the EU by law: H er = 0.3 W/m 2 ) close to that in natural sunlight, but the ratio between UVA (315-400 nm) and UVB irradiances of these lamps is very different from the ratio in the midday summer sun [13]. Nevertheless, sunbed use may lead not only to cosmetic effects (tanning), but can also increase the human vitamin D level [14][15][16]. Thus the dosimetry of UV radiation is needed not only to avoid the harmful effects of UV radiation, such as sunburn, photoaging, and skin cancer, but because of the positive effect of UV radiation to synthesize vitamin D. ...
... Measured sunbed irradiance spectra 3 (1) and bottom (2) sunbed parts and solar spectrum in Oslo (3) combined to CIE action spectra of erythema (4) and previtamin D synthesis in vivo (5) and with action spectrum of previtamin D formation in vitro (6). 2 Nevertheless, it was shown that the individual UV-erythemal sensitivity was a good marker of the individual efficiency of the resulting 25(OH)D 3 in blood serum after solar or solar-simulated UV exposure [19]. Besides, for several sunbeds correlation was found between exposures determined on the basis of erythema dose and increase of 25(OH)D 3 in serum [14][15][16]. ...
... A comparison of South Asians (n = 6) with white Caucasians (n = 4) indicated a similar 38 capacity to synthesise vitamin D when given a higher UVB exposure (21). Genetic differences 39 may also influence vitamin D status with amount of cutaneous precursor 7-dehydrocholesterol 40 and/or efficiency of vitamin D to 25(OH)D conversion as possible factors (15,22,23). Aspects 41 of diet and lifestyle may also negatively impact (24). ...
... Both our actual volunteer data ( Table 2) and statistical model (Table 3) UV-intervention studies in white skinned people (26,39,40). A major contributory factor is 245 anticipated to be UV-induced epidermal thickening and melanin synthesis, reducing cutaneous 246 UVB penetration (24,40). ...
Article
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Background: Vitamin D is essential for bone health, and cutaneous synthesis is an important source. South Asians cannot attain adequate amounts of vitamin D by following general recommendations on summer sunlight exposure at northerly latitudes, and increased exposure may be appropriate for improving their vitamin D status. Objective: We examined the efficacy of a dose range of simulated summer sunlight exposures in raising vitamin D status in UK adults of South Asian ethnicity. Design: In a dose-response study, healthy adults of South Asian ethnicity (n = 60; 20-60 y old) received 1 of 6 ultraviolet exposures ranging from 0.65 to 3.9 standard erythema doses (SEDs), which were equivalent to 15-90 min unshaded noontime summer sunlight at 53.5°N (Manchester, United Kingdom), 3 times/wk for 6 wk, while wearing casual clothes that revealed a 35% skin area. Serum 25-hydroxyvitamin D [25(OH)D] was measured weekly, and dietary vitamin D was estimated. Results: At baseline, all completing participants (n = 51) were vitamin D insufficient [25(OH)D concentrations <20 ng/mL], and a high proportion of participants were deficient [35% of subjects had 25(OH)D concentrations <5 ng/mL, and 90% of subjects had 25(OH)D concentrations <10 ng/mL, which are concentrations at which osteomalacia and rickets occur). The 25(OH)D concentration rose significantly in all dose groups. Postcourse, all participants achieved 25(OH)D concentrations ≥5 ng/mL, whereas only 6 subjects attained 25(OH)D concentrations ≥20 ng/mL. Participants who received exposures ≥1.95 SEDs (equivalent to 45 min unshaded sunlight; n = 33) attained a mean (±SD) 25(OH)D concentration of 15.7 ± 5 ng/mL (mean rise: 8.7 ± 5.7 ng/mL; 95% CI: 6.8, 10.6 ng/mL; P < 0.001), and 94% of subjects achieved concentrations >10 ng/mL. Conclusions: Targeted guidance on sunlight exposure could usefully enhance vitamin D status to avoid deficiency [25(OH)D concentration >10 ng/mL] in South Asians living at latitudes distant from the equator. This trial was registered at the ISRCTN Register (www.isrctn.org) as 07565297.
... 19 Before ceasing operation and dissolving the organization in August 2017 under the pressure of the Melanoma Research Foundation, 22 the Indoor Tanning Association had worked for decades to promote the sunbed industry despite the large evidence of the hazards of indoor tanning, in particular providing the public with misleading messages such as that sunlight is the 'only' way for the body to manufacture the necessary vitamin D. 23 It is true that sunbed use can increase the serum levels of 25-OH-D and several studies have confirmed this finding. 2,[24][25][26][27][28][29][30][31][32][33][34] On the other hand, this increase is in most cases only transient and not sustained if sunbed use is not regular and continuous: a plateau in 25-OH-D level is indeed reached after just a few sunbed sessions due to a balance between photo-production and photo-degradation. 24, 25 Porojnicu et al. 28 observed an increase in vitamin D levels after sunbed exposure but showed that within 8 weeks after the last exposure serum 25-OH-D levels decreased to the initial value. ...
... 2,[24][25][26][27][28][29][30][31][32][33][34] On the other hand, this increase is in most cases only transient and not sustained if sunbed use is not regular and continuous: a plateau in 25-OH-D level is indeed reached after just a few sunbed sessions due to a balance between photo-production and photo-degradation. 24, 25 Porojnicu et al. 28 observed an increase in vitamin D levels after sunbed exposure but showed that within 8 weeks after the last exposure serum 25-OH-D levels decreased to the initial value. Moan et al. 26 confirmed that 25-OH-D levels drop back to pre-exposure levels after 2-4 weeks in winter in northern countries. ...
Article
Vitamin D seems to be associated with a protective effect in a vast range of diseases, including cardiovascular, autoimmune and oncologic conditions. Since ultraviolet (UV) B light is the most important prerequisite for the cutaneous synthesis of vitamin D, sunbeds are able to increase serum vitamin D levels, although only transiently in most cases. In this scenario, the artificial tanning industry relentlessly tries to promote the use of sunbeds as a ‘safe’ therapeutic measure to achieve an adequate serum vitamin D status. The World Health Organization classified UV‐emitting tanning devices, as well as the whole UV spectrum, as group‐1 carcinogens, as they significantly increase the risk of melanoma and non‐melanoma skin cancer. In case of vitamin D deficiency or insufficiency, the current risk‐benefit ratio is therefore in favour of vitamin D supplementation instead of sunbed use. Artificial tanning devices should never be considered as an option to achieve an appropriate vitamin D status. Their supposedly beneficial effects, vastly publicised by the artificial tanning industry, are not worth the carcinogenic risk associated with sunbed use.
... Baseline 25(OH)D 3 values were essentially the same in the PB and FB studies, but interestingly, the effect of baseline on 25(OH)D 3 increase was greater for FB (85% BSA exposed) than PB (3.7% BSA exposed) and raises the possibility of an influence of BSA exposed. Some studies of longer duration than our study have shown a linear increase of 25(OH)D 3 with increasing cumulative UVR exposure followed by a plateau (35,36). We tested various models and found a linear UVR dose response to be the best fit for both individual and pooled PB and FB data over the 2-to 3-wk duration of the studies. ...
Article
Full-text available
Action spectra are important biological weighting functions for risk/benefit analyses of ultraviolet (UV) radiation (UVR) exposure. One important human benefit of exposure to terrestrial solar UVB radiation (∼295 to 315 nm) is the cutaneous synthesis of vitamin D 3 that is initiated by the photoconversion of 7-dehydrocholesterol to previtamin D 3 . An action spectrum for this process that is followed by other nonphotochemical steps to achieve biologically active vitamin D 3 has been established from ex vivo data and is widely used, although its validity has been questioned. We tested this action spectrum in vivo by full- or partial-body suberythemal irradiation of 75 healthy young volunteers with five different polychromatic UVR spectra on five serial occasions. Serum 25-hydroxyvitamin D 3 [25(OH)D 3 ] levels, as the most accurate measure of vitamin D 3 status, were assessed before, during, and after the exposures. These were then used to generate linear dose–response curves that were different for each UVR spectrum. It was established that the previtamin D 3 action spectrum was not valid when related to the serum 25(OH)D 3 levels, as weighting the UVR doses with this action spectrum did not result in a common regression line unless it was adjusted by a blue shift, with 5 nm giving the best fit. Such a blue shift is in accord with the published in vitro action spectra for vitamin D 3 synthesis. Thus, calculations regarding the risk (typically erythema) versus the benefit of exposure to solar UVR based on the ex vivo previtamin D 3 action spectrum require revision.
... The dose of UVB also correlated with the type of lamp, but no correlation between the dose of UVB and the increase of 25(OH)D3 levels was found (58). This might be due to the fact that serum concentrations of 25(OH)D3 were measured at different time points and a plateau level was reached after three weeks, which was also seen in a previous study (70). An in vitro study demonstrated that the dose-response relationship of UV exposure and cholecalciferol synthesis was nonlinear. ...
Chapter
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... 10 This has also been reported in other studies. 13,14 Our results were consistent with a linear model, which gave a strong correlation (r 2 = 0AE763) and may be due to relatively long intervals between every UVB exposure and the small UVB dose of 1 SED. However, the 25(OH)D increase might have reached a plateau for group 1 if the UVB exposures had continued. ...
Article
It is known that ultraviolet (UV) B radiation increases serum 25-hydroxyvitamin D(3) [25(OH)D] level. However, there is uncertainty about the relationship between the maintenance of vitamin D status and UVB. To define the frequency of UVB exposure necessary for maintaining summer 25(OH)D levels during the winter. In total, 60 participants were included from October 2008 to February 2009 (16weeks) and randomized for UVB exposure of 1 standard erythema dose (SED) to ∼88% body area once a week (n=15 completed), every second week (n=14 completed) or every fourth week (n=12 completed). The controls (n=14 completed) had no intervention. Vitamin D was measured at baseline, every fourth week before exposure, and 2days after the last UVB exposure. The 25(OH)D levels (mean) after UVB exposure once a week increased significantly (from 71·9 to 84·5nmolL(-1) ) (P<0·0001), whereas UVB exposure every second week maintained 25(OH)D levels (P=0·16). A significant decrease in mean 25(OH)D levels (from 56·4 to 47·8nmolL(-1) ) (P<0·0001) was found after UVB exposure once every fourth week and for the control group (from 64·8 to 40·1nmolL(-1) ) (P<0·0001). The development in 25(OH)D levels during the 16-week study period were negatively correlated with baseline 25(OH)D (P<0·0001). Further, the increase in 25(OH)D after the last UVB exposure was negatively correlated with the 25(OH)D level just before the last UVB exposure (P<0·0001). Exposure to a UVB dose of 1 SED every second week to ∼88% body area is sufficient for maintaining summer 25(OH)D levels during the winter.
... At high latitudes, marine fish and mammals provided vitamin D, permitting humans to inhabit such regions [18, 82]. As an alternative, artificial solar UVB can also generate vitamin D. A few minutes in a sunbed with whole-body irradiance for those with Fitzgerald skin type 2 can generate about 10 000 IU [83, 84]. Those with skin type 1 should avoid using sunbeds, and those with skin type 5 require about five times longer to generate 10 000 IU. ...
Article
The objective of this work is to estimate the economic burden and premature death rate in Canada attributable to low serum 25-hydroxyvitamin D (25(OH)D) levels. Vitamin D deficiency has been linked to many diseases and conditions in addition to bone diseases, including many types of cancer, several bacterial and viral infections, autoimmune diseases, cardiovascular diseases, and adverse pregnancy outcomes. Canadians have mean serum 25(OH)D levels averaging 67 nmol/L. The journal literature was searched for papers reporting dose-response relationships for vitamin D indices and disease outcomes. The types of studies useful in this regard include randomized controlled trials, observational, cross-sectional, and ecological studies, and meta-analyses. The mortality rates for 2005 were obtained from Statistics Canada. The economic burden data were obtained from Health Canada. The estimated benefits in disease reduction were based on increasing the mean serum 25(OH)D level to 105 nmol/L. It is estimated that the death rate could fall by 37,000 deaths (22,300-52,300 deaths), representing 16.1% (9.7-22.7%) of annuals deaths and the economic burden by 6.9% (3.8-10.0%) or $14.4 billion ($8.0 billion-$20.1 billion) less the cost of the program. It is recommended that Canadian health policy leaders consider measures to increase serum 25(OH)D levels for all Canadians.
... Furthermore, the capacity to synthesize 25(OH)D from the skin declines with age (a 70-year-old 25% of a young adult) [15]. Tanning beds with UVA radiation also produce a small amount of UVB light have also been shown to increase vitamin D levels [19,20]. The finding that active sun exposure habits showed an inverse relationship between BMI and risk of type 2 DM is difficult to interpret. ...
Article
An inverse relationship exists between vitamin D levels and diabetes mellitus. However, little is known about the correlation of sun exposure habits and type 2 diabetes mellitus (DM). A South Swedish cohort study comprising 1000 women from each age group between 25 and 64 (n=40,000) drawn from the Southern Swedish population registry 1990-1992. At the inception of the study 74% answered the inquiry (n=29,518) and provided detailed information on their sun exposure habits and other variables. A follow-up inquiry was sent 2000-2002 which 24,098 women answered. The mean follow-up time was 11 years. Logistic regression analysis was used and the main outcome was the relationship between type 2 DM and sun exposure habits. Our findings indicated that women with active sun exposure habits were at a 30% lower risk of having DM, as compared to those with non-active habits. There was an inverse relation between this risk reduction and BMI. Our investigation gives possible epidemiological explanation to ethnic and seasonal differences in type 2 DM and metabolic control. The study supports that sunlight is involved in the glucose metabolism.
... This difference in mortality is known to epidemiologists as the ''Scottish effect'' and is evident when each social class is separately compared with England [47]. Norway, like Scotland, is exposed to prevailing wet westerly winds but Norwegians eat twice as much fish as Scots and many take a daily cod liver oil supplement, which is the best natural food source of vitamin D [48,49]. ...
Article
The British Isles have a very cloudy climate and as a result receive fewer hours of clear sunlight than most other industrial regions. The majority of people in these islands have low blood levels of vitamin D [25(OH)D] all year round. Few food products are fortified with vitamin D in the UK and the government does not recommend any vitamin D supplement for most adults in the UK. Diseases associated with vitamin D insufficiency such as cancer, heart disease, diabetes (types 1 and 2) and multiple sclerosis are more frequent in the UK, and particularly in Scotland, than in many other European countries and some, such as multiple sclerosis and diabetes (types 1 and 2), are increasing in incidence. Present knowledge suggests that the risk of some chronic diseases could be reduced if vitamin D intake or sun exposure of the population were increased. Yet policy and public health recommendations of the UK government and its agencies (e.g. the Health Protection Agency, the Food Standards Agency) and of Cancer Research UK have failed to take full account of established and putative benefits of vitamin D and/or sunshine. The epidemic of chronic disease in the UK, which is associated with and caused at least in part by vitamin D insufficiency, has not been adequately recognized by these agencies, and too often measures taken by them have been misguided, inappropriate or ineffective.
... The UV source was a commercially available and approved sunbed, equipped with Life Sun S 100 W tubes (Wolff System, Basel, Switzerland). The fluence rates were 0.48 mW/cm 2 in UVB and 12 mW/cm 2 in UVA [17]. ...
Article
Ultraviolet radiation, UV, is widely used for treatment of psoriasis. UV radiation may destroy blood folates in test tubes, but clinical data are scarce. Folate deficiency may increase the risk of cardiovascular diseases, colorectal carcinoma, megaloblastic anemia, pregnancy and birth complications, depression and dementia. The aim of the present study was to investigate the influence of solar radiation, sunbeds and/or broadband UVB phototherapy on the levels of serum and erythrocyte folate in patients with psoriasis or healthy volunteers. Serum and erythrocyte folate status in patients with psoriasis and healthy volunteers was measured before and after exposure to solar radiation, broadband UVB or use of sunbeds. In some cases plasma homocysteine and serum 25-hydroxyvitamin D (25(OH)D) were also measured. Serum and erythrocyte folate levels in healthy volunteers and in psoriasis patients were not influenced to any statistically significant extent after exposure to solar radiation, to single or to multiple UV treatments. However, a slight decay of blood folates and an increase of plasma homocysteine levels were observed in psoriasis patients after exposure to UV radiation. Exposure to sun or sunbeds does not have any significant effect on the levels of blood folate of healthy humans. High doses of broadband UVB phototherapy may slightly decrease blood folates in psoriasis patients. Further studies, using proper, adequate 5-methyltetrahydrofolate methodology, are needed to clarify the influence of broadband phototherapy on folate degradation and the consequences of these on the health of psoriasis patients.
... Some fluorescent sunlamps emit a nonsolar spectrum (with higher ratio of UVA to UVB), which could be more problematic. Sunbeds with UVB are a good source of vitamin D. 19 ...
Article
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The International Agency for Research on Cancer (IARC) released a report, Vitamin D and Cancer, on November 25, 2008. The report focused on the current state of knowledge and level of evidence of a causal association between vitamin D status and cancer risk. Although presenting and evaluating evidence for the beneficial role of UVB and vitamin D in reducing the risk of cancer, it discounted or omitted important evidence in support of the efficacy of vitamin D. The report largely dismissed or ignored ecological studies on the grounds that confounding factors might have affected the findings. The report accepted a preventive role of vitamin D in colorectal cancer but not for breast cancer.The only randomized controlled trial (RCT) on cancer incidence that used a sufficiently high dose of vitamin D (1,100 IU/day) and calcium (1,400-1,500 mg/day) found a 77% reduction in the risk of all-cancer incidence in postmenopausal women who received both, of which approximately 35% reduction in risk was attributed to vitamin D alone. Unfairly, the report dismissed these findings on the basis of a flawed critique.The report called for RCTs of vitamin D supplementation to settle the issue. Although RCTs theoretically would be beneficial, development of sound and effective public health policies does not necessarily depend on them, and the field of vitamin D, calcium and chronic disease has reached the point where RCTs may not be ethical.The IARC report should therefore not form the basis for public health policy decisions.
... Clearly, the sun is an efficient vitamin D producer. Exposure to 1 MED from a sun bed (approximately 20 minutes) would give a similar amount of vitamin D. Several studies have reported that sun bed users get significant amounts of vitamin D from their exposures (14,15). One study (Figure 4) showed that an exposure scheme with 0.5 MED given twice a week over five weeks in winter gave an increase in serum 25(OH)D of about 40% , i.e. a similar increase as seen from late winter to late summer (15). ...
Article
Solar radiation is both the main cause of all types of skin cancer, including cutaneous malignant melanoma (CMM), and the main source of vitamin D accompanied by its beneficial effects. The dilemma lies in that increased sun exposure could lead to an increase in skin cancers and yet is necessary for the better prognosis of internal cancers. Solar radiation varies in intensity and spectral composition with geographic location and time. Of central interest in the present context is that the UVA/UVB ratio can vary. Thus, the UVA/UVB ratio increases with decreasing solar elevation. The ratio is also larger for most sun beds than that in the midday sun, but similar to that in the afternoon sun. This may have large health implications, since vitamin D is exclusively generated by UVB, while UVA and UVB likely play a role in the onset of CMM. Sun and sun beds act similarly: one quantum of radiation at a given wavelength has the same biological effect, irrespective of the source from which it comes. The winter levels of vitamin D are 10 to 100% lower than the summer levels in most populations, but can be brought up to summer levels by moderate sun bed exposure. Doses of 200 IU of vitamin D per day are not sufficiently large to maintain a summer vitamin D status in winter. At high latitudes (>40 degrees) the sun provides no vitamin D in winter. A number of epidemiological studies, interventional studies, animal studies and cell experiments show that vitamin D reduces the risk and/or prognosis of internal cancers. Populations living at high latitudes would probably benefit from moderately increasing their exposure to UVB to provide a good vitamin D status.
... Sun bed users (UVB light) have been shown to have good vitamin D levels (Holick, 2007). Sun beds with UVA light also produce a small amount of UVB light sufficient to increase vitamin D levels (Porojnicu et al, 2008; Thieden et al, 2008). Vitamin D deficiency has also been associated with a 30 – 50% increased risk of colon, prostate, and breast cancer, along with an increased mortality in these cancers (Holick, 2007). ...
Article
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No large cohort study has examined the risk of endometrial cancer in relation to sun exposure. A population-based cohort study of 29,508 women who answered a questionnaire in 1990-92, of whom 24,098 responded to a follow-up enquiry in 2000-02. They were followed for an average of 15.5 years. Among the 17,822 postmenopausal women included, 166 cases of endometrial cancer were diagnosed. We used a multivariate Cox regression analysis adjusting for age and other selected demographic variables to determine the risk of endometrial cancer. Women using sun beds >3 times per year reduced their hazard risk (HR) by 40% (0.6, 95% confidence interval (CI) 0.4-0.9) or by 50% when adjusting for body mass index or physical activity (HR 0.5, 95% CI 0.3-0.9), and those women who were sunbathing during summer reduced their risk by 20% (HR 0.8 95% CI 0.5-1.5) compared with women who did not expose themselves to the sun or to artificial sun (i.e., sun beds). Exposure to artificial sun by the use of sun beds >3 times per year was associated with a 40% reduction in the risk of endometrial cancer, probably by improving the vitamin D levels during winter.
... Except healing of psoriasis, UVB therapy supplies these patients with vitamin D, particularly We did not find any correlation between the increase of the dose of UVB and the increase of serum 25(OH)D3 within the groups. This might be due to that the serum concentrations of 25(OH)D3 were measured at different time points and a plateau level could be reached after 3 weeks which was found in a previous study (16). A recent in vitro study has demonstrated that the dose-response relationship of UV exposure and cholecalciferol synthesis was nonlinear. ...
Article
Phototherapy of psoriasis is an effective treatment. In addition to standard broadband ultraviolet radiation B (UVB), (280-320 nm), narrowband phototherapy (NBUVB) (monochromatic UV between 311 and 312 nm) has become an important treatment for psoriasis. The same wavelength range of UVB (290-315 nm) induces synthesis of vitamin D. The aim was to compare the effect of broadband with NBUVB therapy on vitamin D synthesis in patients with psoriasis. Sixty-eight Caucasian patients (17 women and 51 men) mean age 54.1 +/- 16.0 years, with active plaque psoriasis, were treated with broadband UVB (n=26) or NBUVB (n=42) two to three times/week for 8-12 weeks. The serum concentrations of 25-hydroxyvitamin D (25(OH)D3), 1,25-dihydroxyvitamin D (1,25(OH)(2)D3), intact parathyroid hormone (PTH), calcium and creatinine were measured before the first exposure and after the last dose of radiation. In broadband UVB treated patients, 25(OH)D3 increased from 37.9 +/- 16.9 to 69.4 +/- 19.7 ng/ml (P<0.0001) and in patients treated with NBUVB from 34.8 +/- 11.9 to 55.3 +/- 17.6 ng/ml (P<0.0001) and P=0.008 between the treatment groups. PTH decreased on broadband UVB (P<0.05). The serum concentrations of 1,25(OH)(2)D3, calcium or creatinine remained unaltered. Serum 25(OH)D3 in psoriasis patients increased less with NBUVB than with broadband UVB phototherapy. Psoriasis improved on both regimens.
... This might be due to the fact that serum concentrations of 25(OH)D were measured at different time points and a plateau level was reached after three weeks, which had also been seen in a previous study. 202 A recent in vitro study has demonstrated that the dose-response relationship of UV exposure and cholecalciferol synthesis was nonlinear. It was hypothesized that exposure to additional UV may not result in a proportional increase in vitamin D levels. ...
... The mean vitamin D intake in our population was 5?9 mg/d. We have previously shown that intake in this range is too low to maintain a summer level of 25(OH)D (27) . Our present data show, as expected, a positive but nonsignificant correlation between vitamin D intake and serum 25(OH)D concentration (Table 2). ...
Article
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To investigate the vitamin D status during winter of a healthy population of hospital employees and to assess the correlation between vitamin D status and risk of infections in the upper respiratory tract. One hundred and ten healthy volunteers answered a questionnaire on their solar exposure habits and vitamin D intake and delivered one blood sample for quantification of vitamin D level (serum 25-hydroxyvitamin D (25(OH)D) concentration) during December 2007-January 2008. At the end of the winter we screened for the occurrence of respiratory infections and sought associations with vitamin D status. Bucharest, Romania, 45°N. One hundred and ten healthy hospital employees. Eighty per cent of participants were vitamin D deficient (25(OH)D level below 50 nmol/l). The main determinant of serum 25(OH)D was sun exposure during the summer previous to the study (P = 0·02 in multivariate analysis). Intake of vitamin D, BMI and age played no significant role for the level of 25(OH)D. Overall we found a non-significant negative correlation between 25(OH)D level and new cases of infection (Spearman correlation coefficient of -0·12, P = 0·2). Vitamin D status is alarmingly poor in active, relatively young women residing in Romania. If our results are reproduced by other investigations, action to improve vitamin D status at the population level is necessary. We were not able to show a statistically significant relationship between vitamin D status and infection risk in our material.
... Solar UVB is not strong enough to generate vitamin D in the skin in most European countries in winter but can be a good source in summer (Hypponen and Power, 2007; Porojnicu et al., 2008b). Sunbeds, which in Europe have UV output similar to that of the Mediterranean midday sun but less UVB, can also generate vitamin D. A recent investigation in Norway showed that suberythemal sunbed doses given twice per week for 5 weeks in the winter produced summertime 25(OH)D levels (Porojnicu et al., 2008a). A young individual can generate about 10,000–20,000 IU/day of vitamin D (Adams et al., 1982). ...
Article
Vitamin D has important benefits in reducing the risk of many conditions and diseases. Those diseases for which the benefits are well supported and that have large economic effects include many types of cancer, cardiovascular diseases, diabetes mellitus, several bacterial and viral infections, and autoimmune diseases such as multiple sclerosis. Europeans generally have low serum 25-hydroxyvitamin D [25(OH)D] levels owing to the high latitudes, largely indoor living, low natural dietary sources of vitamin D such as cold-water ocean fish, and lack of effective vitamin D fortification of food in most countries. Vitamin D dose-disease response relations were estimated from observational studies and randomized controlled trials. The reduction in direct plus indirect economic burden of disease was based on increasing the mean serum 25(OH)D level to 40 ng/mL, which could be achieved by a daily intake of 2000-3000 IU of vitamin D. For 2007, the reduction is estimated at euro187,000 million/year. The estimated cost of 2000-3000 IU of vitamin D3/day along with ancillary costs such as education and testing might be about euro10,000 million/year. Sources of vitamin D could include a combination of food fortification, supplements, and natural and artificial UVB irradiation, if properly acquired. Additional randomized controlled trials are warranted to evaluate the benefits and risks of vitamin D supplementation. However, steps to increase serum 25(OH)D levels can be implemented now based on what is already known.
... A number of scientists have shown that exposure on sunbeds increases production of vitamin D. For example, Professor Johan Moan and colleagues have demonstrated that twice weekly exposures on a sunbed can increase the vitamin D level in the body by 40% [495]. Professor Moan goes on to consider the balance of risks and benefits from sunbed exposure, which has not often been addressed. ...
... Studies in humans and pigs have reported that UVR exposure and markers of vitamin D concentration show an initial linear dose-dependent relationship that plateaus after repeated exposures. (50)(51)(52)(53)(54)(55)(56) Figure 3 shows linear dose responses in healthy volunteers exposed to a broadband UVB phototherapy source. A large observational study showed a very steep rise in 25(OH)D versus dose at lower doses followed by a plateau. ...
Article
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ABSTRACT Vitamin D synthesis by exposure of skin to solar ultraviolet radiation (UVR) provides the majority of this hormone that is essential for bone development and maintenance but may be important for many other health outcomes. This process, which is the only well‐established benefit of solar UVR exposure, depends on many factors including genetics, age, health, and behavior. However, the most important factor is the quantity and quality of UVR reaching the skin. Vitamin D synthesis specifically requires ultraviolet B (UVB) radiation that is the minority component (
... Sun beds can provide substantial amounts of vitamin D. Even the socalled UVA sun beds are good sources of vitamin D, since they emit some UVB which is orders of magnitude more efficient than UVA both with respect to vitamin D photosynthesis and melanogenesis (13,48). ...
Article
We have investigated the dependency of incidence rates and prognosis of breast- prostate,-colon-, lung cancer and Hodgink lymphoma on the season of diagnosis. The incidence rates were constant throughout the year while the prognosis was best for cases diagnosed in summer and autumn. The advantage of summer and autumn diagnosis was largest for the youngest patients and slightly larger in the south than in the north of the country. A recent report from the UK is in full agreement with our work. We also determined the serum calcidiol level in persons hospitalized for a number of non - cancerous diseases, and found a seasonal variation, with highest summer levels. Other investigations in Scandinavia and in a number of other countries agree with our findings. We tentatively relate cancer prognosis with the calcidiol level in serum at diagnosis and therapy start.
... 75 Also, it was and is a common practice in Norway to provide supplemental vitamin D through cod liver oil capsules. 77,78 Thus, any effect of vitamin D supplementation on CD risk may be obscured or reduced in this study, if 200 IU is not a material dose with respect to risk, or if other compounds in cod liver oil have confounding effects on CD risk. ...
Article
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The prevalence of celiac disease (CD) has increased significantly in some developed countries in recent decades. Potential risk factors that have been considered in the literature do not appear to provide a convincing explanation for this increase. This has led some researchers to hypothesize that there is a "missing environmental factor" that increases the risk of CD. Based on evidence from the literature, the author proposes that elevation in plasma levels of 1,25-dihydroxyvitamin D [1,25(OH)2D] is a missing risk factor for CD, and relatedly that significant oral vitamin D exposure is a "missing environmental factor" for CD. First, elevated plasma levels of 1,25(OH)2D are common in CD, especially in the newly diagnosed. Second, nine distinct conditions that increase plasma levels of 1,25(OH)2D are either associated with CD or have indications of such an association in the literature. Third, a retrospective study shows that sustained oral vitamin D supplementation in infancy is associated with increased CD risk, and other studies on comorbid conditions support this association. Fourth, large doses of oral vitamin D upregulate many of the same cytokines, chemokines, and toll-like receptors that are upregulated in CD. Fifth, epidemiological evidence, such as the timing of the inception of a CD "epidemic" in Sweden, the increased prevalence of CD in Finland and the United States in recent decades, the unusually low prevalence of CD in Germany, and the differential in prevalence between Finnish Karelians and Russian Karelians, may all be explained by oral vitamin D exposure increasing CD risk. The same is true of some seemingly contradictory results in the literature on the effects of breastfeeding on CD risk. If future research validates this hypothesis, adjustments to oral vitamin D consumption among those who have genetic susceptibility may decrease the risk of CD in these individuals.
... In general, laboratory studies show an initial linear doseresponse between exposure to UV radiation and change in concentration of 25(OH)D, 240 but a plateau with continuing exposures over a longer period of time. 218,[241][242][243] Results suggest that the shape of the dose-response curve depends on the baseline concentration of 25(OH)D, with a greater response to UV irradiation 238 and no plateau effect in those with a lower starting concentration (<50 nmol L −1 ), 244 although conflicting results have also been obtained. 245 Understanding the relationship between the dose of UV radiation, the surface area of skin exposed and the production of vitamin D is important for the development of public health messages. ...
Article
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Due to the implementation of the Montreal Protocol, which has limited, and is now probably reversing, the depletion of the stratospheric ozone layer, only modest increases in solar UV-B radiation at the surface of the Earth have occurred. For many fair-skinned populations, changing behaviour with regard to exposure to the sun over the past half century – more time in the sun, less clothing cover (more skin exposed), and preference for a tan – has probably contributed more to greater levels of exposure to UV-B radiation than ozone depletion. Exposure to UV-B radiation has both adverse and beneficial effects on human health. This report focuses on an assessment of the evidence regarding these outcomes that has been published since our previous report in 2010. The skin and eyes are the organs exposed to solar UV radiation. Excessive solar irradiation causes skin cancer, including cutaneous malignant melanoma and the non-melanoma skin cancers, basal cell carcinoma and squamous cell carcinoma, and contributes to the development of other rare skin cancers such as Merkel cell carcinoma. Although the incidence of melanoma continues to increase in many countries, in some locations, primarily those with strong sun protection programmes, incidence has stabilised or decreased over the past 5 years, particularly in younger age-groups. However, the incidence of non-melanoma skin cancers is still increasing in most locations. Exposure of the skin to the sun also induces systemic immune suppression that may have adverse effects on health, such as through the reactivation of latent viral infections, but also beneficial effects through suppression of autoimmune reactivity. Solar UV-B radiation damages the eyes, causing cataracts and pterygium. UV-B irradiation of the skin is the main source of vitamin D in many geographic locations. Vitamin D plays a critical role in the maintenance of calcium homeostasis in the body; severe deficiency causes the bone diseases, rickets in children and osteomalacia in adults. Although many studies have implicated vitamin D deficiency in a wide range of diseases, such as cancer and cardiovascular disease, more recent evidence is less compelling, with meta-analyses of supplementation trials failing to show a beneficial effect on the health outcomes that have been tested. It continues to be difficult to provide public health messages to guide safe exposure to the sun that are accurate, simple, and can be used by people with different skin types, in different locations, and for different times of the year or day. There is increasing interest in relating sun protection messages to the UV Index. Current sun protection strategies are outlined and assessed. Climatic factors affect the amount of UV radiation received by the skin and eyes, separately from the effect of ozone depletion. For example, cloud cover can decrease or increase the intensity of UV radiation at Earth's surface and warmer temperatures and changes in precipitation patterns may alter the amount of time people spend outdoors and their choice of clothing. The combination of changes in climate and UV radiation may affect the number of pathogenic microorganisms in surface waters, and could have an impact on food security through effects on plant and aquatic systems. It remains difficult to quantify these effects and their possible importance for human health.
... ng/mL, which is a concentration that avoids the severe bone disorders of osteomalacia and rickets. The rapid initial rise in 25(OH)D that lessened and moves toward a plateau as the cumulative dose increased ( Figure 2) was consistent with findings of UV-intervention studies in white-skinned people (26,39,40). A major contributory factor is anticipated to be UV-induced epidermal thickening and melanin synthesis, which reduce cutaneous UVB penetration (24,40). ...
... Fish oil is abundant in fats and fatty acids, which can contain vitamin A, vitamin D, cholesterol, monoglycerides, diglycerides, triglycerides, free fatty acids, phospholipids, and sterylesters [19,20]. Among these components, esters are the main ingredient and they gain most attention for being associated with the bioactivities. ...
Article
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Fish oil has been broadly reported as a potential supplement to ameliorate the severity of some skin disorders such as photoaging, skin cancer, allergy, dermatitis, cutaneous wounds, and melanogenesis. There has been increasing interest in the relationship of fish oil with skin protection and homeostasis, especially with respect to the omega-3 polyunsaturated fatty acids (PUFAs), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). The other PUFAs, such as α-linolenic acid (ALA) and linoleic acid (LA), also show a beneficial effect on the skin. The major mechanisms of PUFAs for attenuating cutaneous inflammation are the competition with the inflammatory arachidonic acid and the inhibition of proinflammatory eicosanoid production. On the other hand, PUFAs in fish oil can be the regulators that affect the synthesis and activity of cytokines for promoting wound healing. A systemic review was conducted to demonstrate the association between fish oil supplementation and the benefits to the skin. The following describes the different cosmetic and therapeutic approaches using fatty acids derived from fish oil, especially ALA, LA, DHA, and EPA. This review summarizes the cutaneous application of fish oil and the related fatty acids in the cell-based, animal-based, and clinical models. The research data relating to fish oil treatment of skin disorders suggest a way forward for generating advances in cosmetic and dermatological uses.
... Porojnicu et al. enrolled 10 healthy volunteers aged between 20 and 35 years, who underwent twice per week whole body exposed to a commercial and approved sunbed [18]. After the exposure period, the baseline concentration of vitamin D was found to be increased by approximately 40%. ...
Chapter
Despite it is now undeniable that indoor tanning exposure is associated with a number of skin cancers, its favorable effects on vitamin D status may bear some underestimated and currently unexplored health benefits. Vitamin D is a fat-soluble vitamin naturally present in a limited number of foods, the concentration of which largely depends on ultraviolet (UV) B sources exposure in humans. A strong, graded, and inverse association has been documented between serum vitamin D and the risk of developing certain types of malignancy, especially colorectal, breast, lung, bladder, and kidney cancers. The overall mortality from any type of cancer is also apparently lower in subjects with increased values of serum vitamin D. Both genomic and nongenomic mechanisms have been identified to support the anticancer effects of vitamin D. Notably, UVB radiation emitted from indoor tanning devices is effective to linearly increase the serum vitamin D concentration, up to twofold. Therefore, some favorable effects against the risk of developing many human diseases, including nonskin cancers, cannot be excluded at first glance, although they may not be only linked to vitamin D status. Further large, prospective or randomized studies should be hence planned to definitely establish whether the unfavorable effects of indoor tanning exposure on skin cancers may be outweighed by the still unexplored benefits attributable to amelioration of vitamin D status.
... However, there is no known evidence showing any difference in disorder outcomes between the effect of oral supplements and sun exposure. Sun exposure is an ineffective mechanism of boosting vitamin D of the human body [9]. Food sources of vitamin D might be required for boosting vitamin D status in human under some circumstances e.g. ...
Article
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After the modern vitamin D hypothesis firstly suggested in 1999 for the allergy pandemic, numerous conditions have been thought to be associated with vitamin D deficiency such as allergy, autoimmunity and neoplasm. Consistently, previous observational studies have linked lower vitamin D status to increased markers of atopy and allergic diseases e.g. atopic dermatitis, anaphylaxis and food allergy. Vitamin D is a “hormone” having important immunomodulatory and immunoregulatory properties. In vitamin D deficient conditions, disrupted mucosal and skin complex integrity and intercurrent infections may act synergistically with allergenic exposure to amplify sensitization risk. There has been emerging data to show that vitamin D can enhance the anti-inflammatory effects of glucocorticoids and potentially be used as adjuvant therapy in steroid-resistant severe asthma. And recent in vivo data suggest that vitamin D supplementation reduce the severity of eczema and allergic rhinitis as well as urticaria symptoms. However, there is presently inadequate evidence to support daily vitamin D supplementation in the prevention and/or treatment of allergic diseases in infants, children and adolescents.
Article
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Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) derived dietary reference values (DRVs) for vitamin D. The Panel considers that serum 25(OH)D concentration, which reflects the amount of vitamin D attained from both cutaneous synthesis and dietary sources, can be used as a biomarker of vitamin D status in adult and children populations. The Panel notes that the evidence on the relationship between serum 25(OH)D concentration and musculoskeletal health outcomes in adults, infants and children, and adverse pregnancy-related health outcomes, is widely variable. The Panel considers that Average Requirements and Population Reference Intakes for vitamin D cannot be derived, and therefore defines adequate intakes (AIs), for all population groups. Taking into account the overall evidence and uncertainties, the Panel considers that a serum 25(OH)D concentration of 50 nmol/L is a suitable target value for all population groups, in view of setting the AIs. For adults, an AI for vitamin D is set at 15 μg/day, based on a meta-regression analysis and considering that, at this intake, the majority of the population will achieve a serum 25(OH)D concentration near or above the target of 50 nmol/L. For children aged 1–17 years, an AI for vitamin D is set at 15 μg/day, based on the meta-regression analysis. For infants aged 7–11 months, an AI for vitamin D is set at 10 μg/day, based on trials in infants. For pregnant and lactating women, the Panel sets the same AI as for non-pregnant non-lactating women, i.e. 15 μg/day. The Panel underlines that the meta-regression was done on data collected under conditions of assumed minimal cutaneous vitamin D synthesis. In the presence of cutaneous vitamin D synthesis, the requirement for dietary vitamin D is lower or may even be zero.
Chapter
This chapter starts with examples of selected two case studies: one is related to third‐generation oil‐in‐water nanosized emulsions developed for ocular topical use and another one belongs to first‐generation oil‐in‐water nanosized emulsions developed specifically for fish oil content's delivery for varied therapeutic applications. The culmination of ophthalmic cationic nanosized emulsions led to the commercial availability of preservative‐free formulation, Cationorm, for the symptomatic treatment of dry eye syndrome. On the other hand, the fish oil‐based emulsion, Omegaven, possesses the total energy content of 112 kcal/100 ml (1.12 kcal ml⁻¹) and thus allows the management of nutrient‐deprived patients admitted in intensive care units. Starting from the formulation hurdles, stability confirmation, safety evaluation, clinical trials, matching of regulatory requirement, successful positioning of products in the market, and possible compliment activation issues are briefly described in the preview of industrial points for these two selected case studies.
Article
Solar radiation is of fundamental importance for human development and health: On the one hand, too much of it can lead to skin ageing and skin cancer, whilst on the other, too little of it can result in vitamin D deficiency, and, thereby lead to high incidence and poor prognosis of internal cancer as well as a number of other diseases. The following data, mostly from Norway, will be reviewed: Variation of ambient solar ultraviolet radiation (UV) and vitamin D status with season and latitude, variation of incidence rates and prognosis of skin cancer and variation of prognosis of internal cancer with latitude and season. In short, the following issues are discussed: 1) Vitamin D level varies with season, but probably not with latitude in Norway, because of an increased intake of vitamin D in the north; 2) Skin cancer incidence rates increase from north to south, as do annual fluence rates of UV radiation, while there seems to be a slight improvement in prognosis from north to south; 3) Prognosis of internal cancer is best for cases diagnosed in the seasons with the best vitamin D status, i.e. in summer and autumn; 4) Incidence rates of cutaneous melanomas have increased from 1960 to 1990, but have decreased slightly thereafter for young people; 5) Changes in sun exposure habits have taken place; 6) An increase in body mass index (BMI) of the population has occurred, which may have led to a worsening of the vitamin D status.
Article
Although first discovered in 1931, vitamin D has seen an increased interest in the scientific community over the past decades, including the dermatology field. Vitamin D promotes calcium and phosphorus absorption; however, the actions of vitamin D are not confined to bone. Indeed, there is now overwhelming and compelling scientific data that vitamin D plays a crucial role in a plethora of cellular function and in extra-skeletal health. Except for fatty fish livers, very few foods naturally contain vitamin D; and the major source of vitamin D comes from skin exposure to sunlight via ultraviolet B. Keratinocytes are unique in the body as not only do they provide the primary source of vitamin D for the body, but they also possess both the enzymatic machinery to metabolize the vitamin D produced to active metabolites. This has been referred to as the photoendocrine vitamin D system. Vitamin D regulates keratinocytes proliferation and differentiation; and plays a role in the defense against opportunistic infections. Multiple factors are linked to vitamin D status; and a growing number of dermatologic diseases has been linked to vitamin D status such as atopic dermatitis, psoriasis, vitiligo, and cutaneous cancers. In this article, we reviewed the potential determinants of vitamin D status, as its implications in dermatologic diseases.
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The primary features of the epidemiology of septicemia in the United States include highest rates in winter and the Northeast, lowest in fall and in the West; higher rates among African Americans than white Americans; a rapid increase in incidence with age; comorbidity with several chronic and infectious diseases; and a rapid increase in incidence rate starting in the early 1980s. This article reviews the literature on the epidemiology of septicemia in the United States, along with the roles of solar ultraviolet-B (UVB) and vitamin D3 related to the more important features. Solar UVB doses in summer are highest in the Southwest and lowest in the Northeast. Serum 25-hydroxyvitamin D [25(OH)D] levels are highest in summer, lowest in winter. African Americans have much lower 25(OH)D levels than those of white Americans. Serum 25(OH)D levels decline rapidly with advancing age. The risk of diseases comorbid with septicemia are generally inversely correlated with serum 25(OH)D levels. Sun-avoidance messages may have led to lower population levels of 25(OH)D, although prevalence of antibiotic-resistant bacteria may have increased. Previous reports have shown that 1,25-dihydroxyvitamin D upregulates human cathelicidin, LL-37, which has antimicrobial as well as antiendotoxin activity. The general agreement between the epidemiology of septicemia in the United States and the variations of solar UVB and the effects of vitamin D supports the hypothesis that both play important roles in reducing the risk of septicemia. Further study is warranted to evaluate this hypothesis.
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Recommendations on limitation of summer sunlight exposure to prevent skin cancer may conflict with requirements to protect bone health through adequate vitamin D levels, the principal source being UVB in summer sunlight. We determined whether sufficient (> or =20 ng ml(-1)) and proposed optimal (> or =32 ng ml(-1)) 25(OH)D levels are attained by following UK guidance advising casual short exposures to UVB in summer sunlight, and performed the study under known conditions to enhance the specificity of future recommendations. During wintertime, when ambient UVB is negligible, 120 white Caucasians, aged 20-60 years, from Greater Manchester, UK (53.5 degrees N) received a simulated summer's sunlight exposures, specifically 1.3 standard erythemal dose, three times weekly for 6 weeks, while wearing T-shirt and shorts. The baseline winter data predict that 5% (confidence interval (CI): 2.7-8.6) of Greater Manchester white Caucasians have deficient (<5 ng ml(-1)) 25(OH)D, 62.5% (CI: 55.2-69.4) have insufficient, and only 2.9% (CI: 1.4-5.6) have proposed optimal levels. After the simulated summer exposures, 90 (CI: 84.9-93.7) and 26.2% (CI: 20.1-33.2) reached 20 and 32 ng ml(-1) 25(OH)D, respectively. Assuming midday UVB levels, sufficient but suboptimal vitamin D status is attained after a summer's short (13 minutes) sunlight exposures to 35% skin surface area; these findings will assist future public health guidance on vitamin D acquisition.
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Background: Solar ultraviolet (UV) radiation during the summer and vitamin D supplementation are two major sources of vitamin D for humans at northern latitudes. However, little is known about the relative efficiency of these two vitamin D sources. Objectives: The main goal was to compare the efficiency of high-dose oral vitamin D3 supplementation (2000 IU per day for 30 days) with a simulated summer UV exposure [10 sunbed sessions to a total dose of 23·8 standard erythema doses (SED)] to improve vitamin D status. Methods: Healthy volunteers were randomized into two groups: group 1 received vitamin D supplementation followed by 10 whole-body sunbed exposures; group 2 started with 10 sunbed exposures followed by vitamin D supplementation. Results: The oral supplementation with vitamin D3 resulted in a mean (SEM) serum 25-hydroxyvitamin D [25(OH)D] increase of 25·3 (5·4) nmol L(-1) . A similar increase, 19·8 (5·4) nmol L(-1) , was observed after simulated summer UV exposure. At the end of the study, serum 25(OH)D concentrations were similar in both groups. Conclusions: Twice-weekly whole-body sunbed exposure to a dose of 4·8 SED is equal to 2000 IU daily of oral vitamin D supplementation for 30 days and enough to achieve and maintain serum 25(OH)D concentrations > 75 nmol L(-1) in ~55% of cases. Based on our calculations, this dose corresponds to a cumulative weekly whole-body exposure of 3·4 SED (~ 40 min around midday during the summer at the latitude of Oslo).
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While there is limited documentation that certain indoor tanning lamps effectively produce vitamin D, the diversity of such devices has not been extensively surveyed. This study compares the spectral effectiveness of a variety of tanning units, and solar spectra, for ultraviolet (UV) photosynthesis of pre-vitamin D3 (preD3) and UV induced erythema. Well-established techniques exist for the calculation of spectral effectiveness for photobiological responses that have defined action spectra. Using spectroradiometric data from sunlamp measurements, and standard solar reference spectra, we computed effective irradiances using the CIE action spectrum for the production of preD3 in human skin and the ISO/CIE human erythema reference action spectrum. We found, as with sunlight at different times or latitude, the preD3 and erythemal effectiveness of sunlamps varied as a function of the UV-B proportion of the spectrum. Ratios of sunlamp preD3 to erythemal effectiveness ranged from approximately 0.5 to nearly 2.0, similar to ratios for sunlight. Optimal risk to benefit conditions for preD3 from solar UV exposure occurs under high solar altitude, low zenith angle, midday midsummer sunlight. Analogous optimal preD3 exposure conditions are provided by low to intermediate pressure sunlamps with greater UV-B spectral overlap with the preD3 action spectrum. Similar to low altitude or high latitude sunlight, high pressure tanning units, filtered for negligible UV-B emissions, have insignificant vitamin D benefit. We conclude that while vitamin D can be made by both UVB exposure from indoor tanning units and by exposure UVB from sunlight, the effect is also comparably variable. Unlike sunlight, indoor tanning offers privacy and environmental conditions for practical full body exposure, lowering the requisite exposure per skin surface area, and device timers limit the potential of overexposure. Guidance for optimal use of tanning sources for vitamin D benefit is needed.
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Vitamin D plays an important role in cancer prevention and prognosis. A good vitamin D status at the time of diagnosis and therapy start seems to improve survival. Due to the sun, the serum concentration of 25-hydroxyvitamin D [25(OH)D] is higher in summer than in winter. The vitamin D status in Norway and its impact on cancer prognosis was reviewed: 137,706 cases of breast, colon and prostate cancer and Hodgkin’s lymphoma were analysed with respect to survival 3 years after diagnosis. The survival rates for these cancer forms were about 20% higher for summer diagnosis than for winter diagnosis. The effect was largest for the youngest patients. The concentration of 25(OH)D in serum was 49 ± 2nmol/l in the winter and 66 ± 5nmol/l in the summer, while the level of 1,25-dihydroxyvitamin D [1,25(OH)2D] remained almost constant during the year, except for persons with high body mass index, for whom there was a similar seasonal variation as for 25(OH)D. It seems that 25(OH)D, rather than 1,25(OH)2D, may be the main metabolite influencing cancer survival. Vitamin D supplementation or, alternatively, exposure to ultraviolet radiation may be considered as adjuvants in cancer therapy. Key WordsSun–vitamin D–cancer prognosis
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The evidence is increasing that higher serum 25-hydroxyvitamin D [25(OH)D] levels reduce the risk of many types of cancer. Ecological and observational studies yield the strongest evidence, with support from studies of mechanisms. A key question is identifying the relation between serum 25(OH)D level and cancer incidence. Meta-analyses of such studies is a reasonable approach to determine the serum 25(OH)D level-cancer incidence relation. This paper reports new meta-analyses for breast and colorectal cancers. Currently, the journal literature offers seven prospective breast cancer and ten prospective colorectal cancer studies that can be used. The data for these studies graphed and compared. Data from some of the studies were multiplied by factors to bring all the studies into reasonable agreement with a tentative dose-response relation. The data were fit with a variety of functions; the best fits were nonlinear functions that tended to asymptotically reach a lower odds ratio at higher serum 25(OH)D levels. These analyses estimated that the 50% reduction in incidence occurs for a value of 78 nmol/L compared with the value at 24 nmol/L for breast cancer, and a value of 60 nmol/L compared with the value at 15 nmol/L for colorectal cancer. Although these results are reasonable, some concern exists that a single serum 25(OH)D level, measured years prior to diagnosis of cancer, does not adequately represent the serum levels for the entire period before diagnosis. Future prospective studies should include more serum 25(OH)D level measurements during the study course.
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Phototherapy (broadband UVB (BUVB), narrowband UVB (NBUVB) and heliotherapy) is commonly used treatment modalities for widespread psoriasis. Vitamin D3, cholecalciferol, is produced in the epidermis by ultraviolet radiation (290-315 nm) of 7-dehydrocholesterol. 25-hydroxyvitamin D [25(OH)D], and 1,25-dihydroxyvitamin D [1,25(OH)(2)D] are the major circulating metabolites. Sun exposure is the strongest factor influencing 25(OH)D. The similar wavelength spectrum of UVB responsible for D vitamin synthesis (BUVB, 280-315 nm) has been successfully used for years to treat psoriasis. The aim was: (1) To increase the knowledge about the effects of phototherapy on vitamin D production during treatment of psoriasis. (2) To examine if there were differences between the effect of BUVB, NBUVB and heliotherapy on vitamin D synthesis in psoriasis patients. Serum concentrations of 25(OH)D, 1,25(OH)(2)D, PTH, calcium and creatinine, measured before and after phototherapy in white Caucasian patients with moderate to severe active plaque psoriasis, were aggregated from three studies. Psoriasis improved in all patients, with a reduction in PASI ((Psoriasis Area and Severity Index) score of about 75% on all regimes. Serum 25(OH)D increased and PTH decreased after the phototherapy. The increase in 25(OH)D was higher in the BUVB treated patients compared with NBUVB. There was no correlation between the dose of UVB and the increase of 25(OH)D. UVB and heliotherapy improved the psoriasis score, increased the serum 25(OH)D levels and reduced the serum PTH concentrations. Vitamin D production in psoriasis patients increased less with NBUVB than with BUVB phototherapy.
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Emerging scientific evidence strongly supports the beneficial role of vitamin D in reducing the risk of incidence and death from many chronic and infectious diseases. This study estimates increases in melanoma and nonmelanoma skin cancer mortality rates and decreases in chronic and infectious disease mortality rates in the US from the standpoint of approximately doubling population doses of solar UVB to increase mean serum 25-hydroxyvitamin D levels from 16 ng/mL for black Americans and 25 ng/mL for white Americans to 45 ng/mL. The primary benefits are expected to come from reductions in cancer and cardiovascular diseases. Although a few thousand excess deaths per year might occur from melanoma and skin cancer, the avoided premature death rate could be near 400,000/ year, with most of the avoided deaths coming late in life. While oral sources of vitamin D could be used instead of UVB or when UVB irradiance is not available, public health policies do not yet recommend the 3,000-4,000 IU/day required to raise serum 25-hydroxyvitamin D levels to the levels required for optimal health, which would be required before vitamin D fortification levels in food can be raised. Until then, moderate solar UVB irradiance remains an import source, and the health benefits greatly outweigh the risks.
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Some researchers have suggested to use an indoor tanning device (solarium) as a vitamin D source for disease prevention. The article is based on non-systematic searches in PubMed and ISI, and the authors' experience from epidemiologic research and studies of solarium irradiance. Vitamin D deficiency is an established risk factor for rickets in children and osteomalacia in adults; and is associated with an increased risk of osteoporosis and fractures. Several studies have found a beneficial role of vitamin D on both incidence and prognosis for other diseases, e.g. cancer, but causal relationships with vitamin D cannot yet be concluded. Sun exposure, our main source of vitamin D, is also an established risk factor of skin cancer. Moderate sun exposure generally provides an adequate amount of vitamin D during summer. Dietary intake of vitamin D is adamant when sun exposure is low. Solarium use seems to increase. Mean irradiance from solariums is higher than that from the summer sun in Oslo; 1.5 times higher for UVB and 3.5 times for UVA . Use of solarium increases the risk of skin cancer and was classified as carcinogenic to humans in 2009; positive health effects are not sufficiently documented. Recommendations on restricted solarium use should be maintained.
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Next to the adverse effects of solar UV exposure, the beneficial effects mediated by vitamin D(3) have come into the limelight. The question then is "how much sun exposure do we actually need?" Estimates have been made, but the data are not quite adequate. The groups of Drs. Rhodes and Webb bridged the gap between experiments and everyday life by a study in which 109 volunteers were exposed in mid-winter to simulated solar UV radiation in summertime clothing at dosages of 1.3 SED three times a week. Thus, 90% reached sufficiently high vitamin D statuses (>50 nmol L(-1)). In this issue, these researchers transpose these experimental exposures in a cabinet to summertime noon exposures of people walking around for about half an hour in open terrain on a clear day in Manchester, UK. This result is an improvement over earlier estimates and shows that casual mid-day summer sun exposure should indeed suffice.
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The International Agency for Research on Cancer (IARC) reported meta-analyses of the association of cutaneous malignant melanoma (CMM), finding significant correlations with ever use of sunbeds and first use of sunbeds prior to age 35 years; it did not claim that the associations showed causal links. However, some observational studies in the meta-analysis included individuals in the UK with skin phenotype at increased genetic risk of CMM without adjustment for skin phenotype. Treating the five UK studies separately from the other 14 corrected this oversight. In the original study, the summary relative risk (RR ) of CMM with respect to sunbed use was 1.15 (95% confidence interval [CI], 1.00-1.31). In this study, the similar RR was 1.20 (95% CI, 1.03-1.38). The RR for the five UK studies was 2.09 (95% CI, 1.14-3.84), whereas the RR for the other 14 studies was 1.09 (95% CI, 0.96-1.24). For first use of sunbeds prior to age 35 years, the IARC found a summary RR of 1.75 (95% CI, 1.35-2.36). This study plotted the RRs versus latitude of each study population, with a linear regression analysis carried out for all but the one UK study. The RR increased at 0.077 per degree of latitude and the regression explained 67% of the variance. It is also argued that factors other than sunbed use explain the increasing worldwide trends in CMM. Because solar-UV-simulating sunbeds induce production of vitamin D, the health benefits of their use greatly outweigh any possible risks.
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To review the health effects of solar radiation, sunbeds and vitamin D. The literature was searched in the electronic database MEDLINE to indentify published data between 1981 and 2011. Studies were included if they reported relative risk for cutaneous malignant melanoma (CMM) associated with sunbed use, vitamin D and UV effects on human health. Data from different time periods for populations at different latitudes. Persons of different ages and ethnic groups. UV from sun and sunbeds is the main vitamin D source. Young people with white or pigmented skin in northern Europe have a low vitamin D status. A number of health benefits from sufficient levels of vitamin D have been identified. However, UV exposure has been suspected of causing skin cancer, notably CMM, and authorities warn against it. The overall health benefit of an improved vitamin D status may be more important than the possibly increased CMM risk resulting from carefully increasing UV exposure. Important scientific facts behind this judgement are given.
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A systematic review of publications addressing change in vitamin D status (25-hydroxyvitamin D; 25OHD) after exposure to ultraviolet (UV) radiation identified 2001 independent peer-reviewed publications. Of these, 21 used artificial sources of UV radiation, met all inclusion criteria and were quality assured; 13 publications used solar radiation and met sufficient inclusion criteria to be retained as supporting evidence; one further included publication used both solar and artificial sources. The review consistently identified that low dose, sub-erythemal doses are more effective for vitamin D synthesis than doses close to a minimum erythema dose; increasing skin area exposed increases the amount of vitamin D synthesised although not necessarily in a linear manner; constant dosing leads to a dose-dependent plateau in 25OHD, and dose-response is greatest at the start of a dosing regime; there is a large interpersonal variation in response to UV exposure. Fourteen of the studies using artificial sources of radiation were used to determine a dose-response relationship for change in 25OHD on whole-body exposure to repeated sub-erythemal doses of UV radiation, taking the form Δ25OHD (nmol/L) = A ln(SDD) + B. This helps quantify our understanding of UV as a source of vitamin D and enables exposure regimes for safe synthesis of vitamin D to be assessed. Specific studies of people with pigmented skin (Fitzpatrick skin types 5 and 6) were rare and this dose-response is only applicable to white-skinned individuals as skin type is a determinant of response to UV radiation. Findings provide information for vitamin D guidance updates.
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Information on the variation in carcinogenicity with wavelength is crucial in risk assessments for skin cancers induced by UV radiation. Until recently the wavelength (lambda) dependencies of other detrimental UV effects, such as sunburn, have been used as substitutes. Direct information on the lambda dependency can only be obtained from animal experiments. To this end we accumulated a large data set on skin tumors induced by chronic UV exposure of albino SKH:HR1 mice (14 different broadband UV sources and about 1100 mice); the data come from the Photobiology Unit of the former Skin and Cancer Hospital in Philadelphia and from the Department of Dermatology of the University of Utrecht. The lambda dependency was extracted from this data set (a statistically satisfactory description with chi 2 = 13.4, df = 7) and represented by the Skin Cancer Utrecht-Philadelphia action spectrum, i.e., a set of factors to weight the exposures at different wavelengths according to their respective effectiveness (inversely proportional to the daily exposure required for a median tumor induction time of 300 days). The fits obtained with other already available action spectra proved to be poor (chi 2 > 60, df = 11). The maximum effectiveness was found at 293 nm, and above 340 nm the effectiveness showed a shoulder at about 10(-4) of the maximum. A sensitivity analysis of the final solution for the lambda dependency showed a large margin of uncertainty above 340 nm and an information gap below 280 nm. The large variation in tumor responses in the present data set can be transformed to a coherent, common dose-response relationship by proper spectral weighting with this single action spectrum.
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To evaluate the effect of seasonal variations in UV B-exposure on calcium absorption and bone turnover in young women with the overall goal to assess the potential benefit of a vitamin D supplementation during wintertime. Cross-sectional study. Area of Bonn, Germany (51 degrees N). Thirty-eight women (24.5+/-0.5 y) studied in winter and 38 females of the same age (24.7+/-0.4 y) studied in summer. As estimated by a 4 d food record, both groups had similar dietary calcium and phosphorus intakes (> 1200 mg/d, respectively) covering actual recommendations. Significant reductions in serum concentrations of 25-hydroxyvitamin D (25OHD) and calcitriol, fractional calcium absorption (Fc220, measured by means of a stable strontium test), 24h urinary calcium and 24h urinary phosphorus excretion were observed during wintertime. 25OHD but not calcitriol was correlated with Fc220 values and with 24h urinary phosphorus excretion. Moreover, Fc220 was related to 24 h urinary calcium excretion. Fasting 2 h-urinary deoxypyridinoline concentrations (biomarker of bone resorption) and serum levels of carboxyterminal propeptide of type I procollagen (biomarker of bone formation) showed no differences between summer and winter. Our data indicate a decrease in intestinal calcium and phosphorus absorption during wintertime, most likely because of a reduction in serum 25OHD levels. Since bone turnover was not affected by the seasonal differences in mineral metabolism, there is no objective for young women with high calcium intake to supplement vitamin D during wintertime.
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The biologically important process of endogenous synthesis of vitamin D under UV solar irradiation is widespread in the biosphere and inherent to most animals and plants. A new method of biological dosimetry of UV radiation based on an in vitro model of vitamin D synthesis ('D-dosimeter') is discussed. Unlike the vast majority of biodosimeters, the action of which depends on the UV sensitivity of DNA and thus reflects damaging effects of UV radiation, the process of vitamin D synthesis is beneficial by its nature. To date, the complex network of photo- and thermoreactions of vitamin D synthesis in vitro is well understood, and an adequate mathematical model is available, ensuring a link between biological and physical units. Original spectral analysis of the multicomponent photoisomer mixture has been specially designed to provide the most effective use of the D-dosimeter in situ. Spectral selectivity (exceptional sensitivity of certain parameters to the spectral composition of UV radiation) extends the usefulness of the method.
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Vitamin D status is currently considered among the relevant determinants of skeletal integrity. Since vitamin D levels present seasonal variations, we longitudinally studied young healthy men and women in order to investigate the related physiologic modifications of both calcium homeostasis and bone remodeling. Thirty-two men (mean age 39.4 +/- 7.8 years) and 58 premenopausal women (aged 36.9 +/- 6.4 years) from southern Italy were studied. In all subjects the following parameters were measured both in winter and in summer: serum calcium, phosphorus, creatinine, total alkaline phosphatase activity, 25-hydroxyvitamin D (25OHD), parathyroid hormone (PTH), osteocalcin (BGP), together with urinary calcium (Ca/Cr), total pyridinoline (Pyr/Cr) and deoxypyridinoline (d-Pyr/Cr), corrected for creatinine excretion. In both sexes 25OHD levels were significantly higher in summer, while PTH values were lower, than in winter. The prevalence of hypovitaminosis D, defined by concentrations of 25OHD lower than 30 nmol/l, was 17.8% in winter and 2.2% in summer in the whole sample, while it was 27.8% and 3.4%, respectively, among female subjects. Indeed male subjects did not display hypovitaminosis D, having throughout the year significantly higher calcium and 25OHD levels together with lower PTH values, than the women. Moreover, alkaline phosphatase total activity was more elevated in men both in winter and in summer. In women, during winter, bone remodeling markers levels were higher while urinary calcium levels were lower than in summer. In the whole sample serum 25OHD correlated positively with serum calcium and inversely with PTH. The seasonal percentage variations in PTH were inversely correlated with those of Ca/Cr. Our results show a relatively high prevalence of subclinical vitamin D deficiency among young healthy women from southern Italy. Significant gender-specific differences have been demonstrated in both calcium homeostasis and skeletal remodeling indexes; the seasonal fluctuations in the vitamin D-PTH axis are accompanied by cyclical variations of bone turnover rate, which were more pronounced in women.
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Vitamin D is metabolised by a hepatic 25-hydroxylase into 25-hydroxyvitamin D (25(OH)D) and by a renal 1alpha-hydroxylase into the vitamin D hormone calcitriol. Calcitriol receptors are present in more than thirty different tissues. Apart from the kidney, several tissues also possess the enzyme 1alpha-hydroxylase, which is able to use circulating 25(OH)D as a substrate. Serum levels of 25(OH)D are the best indicator to assess vitamin D deficiency, insufficiency, hypovitaminosis, adequacy, and toxicity. European children and young adults often have circulating 25(OH)D levels in the insufficiency range during wintertime. Elderly subjects have mean 25(OH)D levels in the insufficiency range throughout the year. In institutionalized subjects 25(OH)D levels are often in the deficiency range. There is now general agreement that a low vitamin D status is involved in the pathogenesis of osteoporosis. Moreover, vitamin D insufficiency can lead to a disturbed muscle function. Epidemiological data also indicate a low vitamin D status in tuberculosis, rheumatoid arthritis, multiple sclerosis, inflammatory bowel diseases, hypertension, and specific types of cancer. Some intervention trials have demonstrated that supplementation with vitamin D or its metabolites is able: (i) to reduce blood pressure in hypertensive patients; (ii) to improve blood glucose levels in diabetics; (iii) to improve symptoms of rheumatoid arthritis and multiple sclerosis. The oral dose necessary to achieve adequate serum 25(OH)D levels is probably much higher than the current recommendations of 5-15 microg/d.
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Although sun exposure is an established cause of cutaneous malignant melanoma, possible interactions with host factors remain incompletely understood. Here we report the first results from a large prospective cohort study of pigmentation factors and sun exposure in relation to melanoma risk. The Women's Lifestyle and Health Cohort Study included 106 379 women from Norway and Sweden who were aged 30-50 years in 1991 or 1992 when they completed an extensive questionnaire on personal characteristics and exposures. Linkages to national registries ensured complete follow-up through December 31, 1999. Poisson regression models were used to estimate relative risks (RRs). All statistical tests were two-sided. During an average follow-up of 8.1 years, 187 cases of melanoma were diagnosed. Risk of melanoma was statistically significantly associated with increasing body surface area (RR for > or =1.79 m2 versus < or =1.61 m2 = 1.60, 95% confidence interval [CI] = 1.03 to 2.48; P(trend) =.02), number of large asymmetric nevi on the legs (RR for > or =7 nevi versus 0 nevi = 5.29, 95% CI = 2.33 to 12.01; P(trend)<.001), hair color (RR for red versus dark brown or black = 4.05, 95% CI = 2.11 to 7.76; P(trend)<.001), sunburns per year at ages 10-19, 20-29, and 30-39 years (P(trend)<.001, P(trend) =.03, and P(trend) =.05, respectively), and use of a device that emits artificial light (solarium) one or more times per month (P =.04). Our results confirm previous findings that hair color, number of nevi on the legs, and history of sunburn are risk factors for melanoma and suggest that use of a solarium is also associated with melanoma risk. Adolescence and early adulthood appear to be among the most sensitive age periods for the effects of sunburn and solarium use on melanoma risk. However, it may be too early to see the full effect of adult exposures in this cohort.
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Vitamin D is made in the skin on exposure to solar radiation, and it is necessary to optimal skeletal health. Subjects who use a tanning bed that emits ultraviolet B radiation (290-315 nm) are likely to have higher 25-hydroxyvitamin D [25(OH)D] concentrations than do subjects who do not regularly use a tanning bed. The first objective of this study was to ascertain whether subjects who regularly use a tanning bed have higher 25(OH)D concentrations than do subjects who do not use a tanning bed. The second objective was to ascertain whether higher 25(OH)D concentrations correlated positively with bone mineral density. This cross-sectional analysis examined 50 subjects who used a tanning bed at least once a week and 106 control subjects. Each subject gave a blood specimen for measurement of serum 25(OH)D and parathyroid hormone concentrations. Each subject underwent bone mineral density testing of the hip and spine. Subjects who used a tanning bed had serum 25(OH)D concentrations 90% higher than those of control subjects (115.5 +/- 8.0 and 60.3 +/- 3.0 nmol/L, respectively; P <0.001). Subjects who used a tanning bed had parathyroid hormone concentrations 18% lower than those of control subjects (21.4 +/- 1.0 and 25.3 +/- 0.8 pg/mL, respectively; P=0.01). Tanners had significantly higher BMD and z scores at the total hip than did nontanners. The regular use of a tanning bed that emits vitamin D-producing ultraviolet radiation is associated with higher 25(OH)D concentrations and thus may have a benefit for the skeleton.
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Melanoma incidence and survival are positively associated, both geographically and temporally. Solar elastosis, a histologic indicator of cutaneous sun damage, has also been positively associated with melanoma survival. Although these observations raise the possibility that sun exposure increases melanoma survival, they could be explained by an association between incidence and early detection of melanoma. We therefore evaluated the association between measures of skin screening and death from cutaneous melanoma. Case subjects (n = 528) from a population-based study of cutaneous melanoma were followed for an average of more than 5 years. Data, including measures of intermittent sun exposure, perceived awareness of the skin, skin self-screening, and physician screening, were collected during in-person interviews and review of histopathology and histologic parameters (i.e., solar elastosis, Breslow thickness, and mitoses) for all of the lesions. Competing risk models were used to compute risk of death (hazard ratios [HRs], with 95% confidence intervals [CIs]) from melanoma. All statistical tests were two-sided. Sunburn, high intermittent sun exposure, skin awareness histories, and solar elastosis were statistically significantly inversely associated with death from melanoma. Melanoma thickness, mitoses, ulceration, and anatomic location on the head and neck were statistically significantly positively associated with melanoma death. In a multivariable competing risk analysis, skin awareness (with versus without, HR = 0.5, 95% CI = 0.3 to 0.9, P = .022) and solar elastosis (present versus absent, HR = 0.4, 95% CI = 0.2 to 0.8, P = .009) were strongly and independently associated with melanoma death after adjusting for Breslow thickness, mitotic index, and head and neck location, which were also independently associated with death. Sun exposure is associated with increased survival from melanoma.
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A number of studies have been conducted evaluating the risk of cutaneous malignant melanoma after exposure to sunlamps and/or sunbeds. The proportion of subjects in the individual studies who have reported exposure has, in general, been modest, and the resulting risk estimates for melanoma have been unstable with wide 95% confidence intervals (95% CI). The inconclusive results seen in individual studies have resulted in confusion as to the carcinogenicity of these devices. We conducted a systematic review and meta-analysis of these studies. A review of the literature from Jan 1, 1984 to April 2004 using MEDLINE identified 12 case-control studies and 1 cohort study which quantitatively evaluated the use of sunlamps and/or sunbeds and subsequent melanoma. After applying exclusion/inclusion criteria, 9 case-control and 1 cohort study provided data for the analysis. Summary odds ratios (OR) and 95% CIs for sunlamp/sunbed use and subsequent melanoma were calculated using a random-effect model. Ten studies provided data for assessment of melanoma risk among subjects who reported "ever" being exposed compared with those "never" exposed. A positive association was found between exposure and risk (summary OR, 1.25; 95% CI, 1.05-1.49). Significant heterogeneity between studies was present. Evaluation of the metrics "first exposure as a young adult" (5 studies) and "longest duration or highest frequency of exposure" (6 studies) also yielded significantly elevated risk estimates (summary OR, 1.69; 95% CI, 1.32-2.18, and 1.61; 95% CI, 1.21-2.12, respectively, with no heterogeneity in either analysis). Results indicate a significantly increased risk of cutaneous melanoma subsequent to sunbed/sunlamp exposure.
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Background: Obesity is associated with vitamin D insufficiency and secondary hyperparathyroidism. Objective: This study assessed whether obesity alters the cutaneous production of vitamin D3 (cholecalciferol) or the intestinal absorption of vitamin D2 (ergocalciferol). Design: Healthy, white, obese [body mass index (BMI; in kg/m²) ≥ 30] and matched lean control subjects (BMI ≤ 25) received either whole-body ultraviolet radiation or a pharmacologic dose of vitamin D2 orally. Results: Obese subjects had significantly lower basal 25-hydroxyvitamin D concentrations and higher parathyroid hormone concentrations than did age-matched control subjects. Evaluation of blood vitamin D3 concentrations 24 h after whole-body irradiation showed that the incremental increase in vitamin D3 was 57% lower in obese than in nonobese subjects. The content of the vitamin D3 precursor 7-dehydrocholesterol in the skin of obese and nonobese subjects did not differ significantly between groups nor did its conversion to previtamin D3 after irradiation in vitro. The obese and nonobese subjects received an oral dose of 50000 IU (1.25 mg) vitamin D2. BMI was inversely correlated with serum vitamin D3 concentrations after irradiation (r = −0.55, P = 0.003) and with peak serum vitamin D2 concentrations after vitamin D2 intake (r = −0.56, P = 0.007). Conclusions: Obesity-associated vitamin D insufficiency is likely due to the decreased bioavailability of vitamin D3 from cutaneous and dietary sources because of its deposition in body fat compartments.
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Highly sensitive assays have been developed that enable 25-hydroxycholecalciferol (25-hydroxyvitamin D3) and 25-hydroxyergocalciferol (25-hydroxyvitamin D2) to be measured in the same serum sample. With these assays it has been shown that endogenously produced cholecalciferol (vitamin D3) is important in man; the findings further emphasize the role of vitamin D metabolites as hormones rather than vitamins in the traditional sense. Dietary sources of vitamin D appear to be inadequate and vitamin D deficiency has been shown to be the cause of rickets and osteomalacia in Asian immigrants to Britain. This condition may be readily treated with small doses of vitamin D. In addition, sub-clinical deficiency was found in the Asian community. In the elderly, also, vitamin D deficiency was established as an important cause of osteomalacia and again evidence for the existence of a sub-clinical deficiency state was found. It is therefore suggested that the present prophylactic practices should be reviewed. Secondary hyperparathyroidism (reflected by elevated concentrations of circulating immunoassayable parathyroid hormone) was shown to be the rule rather than the exception in vitamin D deficiency. Some patients, however, had failed to respond to a hypocalcaemic stimulus. In others, there were high concentrations of parathyroid hormone despite normal serum calcium concentrations. Thus the relationship between parathyroid hormone and metabolites of vitamin D may not be mediated through changes in serum calcium alone, and it is postulated that metabolites of vitamin D may directly affect the secretion of parathyroid hormone.
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Exposure to solar ultraviolet (UV) radiation is a known cause of skin cancer. Sunbed use represents an increasingly frequent source of artificial UV exposure in light-skinned populations. To assess the available evidence of the association between sunbed use and cutaneous malignant melanoma (melanoma) and other skin cancers, a systematic review of the literature till March 2006 on epidemiological and biological studies on sunbed use was performed in Pubmed, ISI Web of Science, Embase, Pascal, Cochrane library, Lilacs and Medcarib. Search for keywords in the title and in the abstract was done systematically and supplemented by manual searches. Only case-control, cohort or cross-sectional studies were selected. Data were abstracted by means of a standardized data-collection protocol. Based on 19 informative studies, ever-use of sunbeds was positively associated with melanoma (summary relative risk, 1.15; 95% CI, 1.00-1.31), although there was no consistent evidence of a dose-response relationship. First exposure to sunbeds before 35 years of age significantly increased the risk of melanoma, based on 7 informative studies (summary relative risk, 1.75; 95% CI, 1.35-2.26). The summary relative risk of 3 studies of squamous cell carcinoma showed an increased risk. For basal cell carcinoma, the studies did not support an association. The evidence does not support a protective effect of the use of sunbeds against damage to the skin from subsequent sun exposure. Young adults should be discouraged from using indoor tanning equipment and restricted access to sunbeds by minors should be strongly considered.
Article
Circulating concentrations of 25-hydroxyvitamin D (25-OHD) were measured during short-term and long-term oral treatment with 25-hydroxycholecalciferol (25-OHD3), 25-H.C.C.) or with vitamin D in over 200 subjects over a period of 5 years. Ten times more vitamin D than 25-OHD3 was required to produce equivalent plasma-25-OHD concentrations. Plasma-25-OHD was a power function of dosage with both compounds. These data indirectly measure the superior therapeutic potency of 25-OHD3, show that dose-response relations with both compounds may be useful in diagnosis, and indicate that there are pronounced constraints on 25-hydroxylation of vitamin D. Together with the effects of ultraviolet light, now shown to be equivalent to oral vitamin D in doses of 8000-10 000 I.U. daily, these constraints may protect against vitamin-D deficiency in winter.
Article
Highly sensitive assays have been developed that enable 25-hydroxycholecalciferol (25-hydroxyvitamin D3) and 25-hydroxyergocalciferol (25-hydroxyvitamin D2) to be measured in the same serum sample. With these assays it has been shown that endogenously produced cholecalciferol (vitamin D3) is important in man; the findings further emphasize the role of vitamin D metabolites as hormones rather than vitamins in the traditional sense. Dietary sources of vitamin D appear to be inadequate and vitamin D deficiency has been shown to the cause of rickets and osteomalacia in Asian immigrants to Britain. This condition may be readily treated with small doses of vitamin D. In addition, sub-clinical deficiency was found in the Asian community. In the elderly, also, vitamin D deficiency was established as an important cause of osteomalacia and again evidence for the existence of a sub-clinical deficiency state was found. It is therefore suggested that the present prophylactic practices should be reviewed. Secondary hyperparathyroidism (reflected by elevated concentrations of circulating immunoassayable parathyroid hormone) was shown to be the rule rather than the exception in vitamin D deficiency. Some patients, however, had failed to respond to a hypocalcaemic stimulus. In others, there were high concentrations of parathyroid hormone despite normal serum calcium concentrations. Thus the relationship between parathyroid hormone and metabolites of vitamin D may not be mediated through changes in serum calcium alone, and it is postulated that metabolites of vitamin D may directly affect the secretion of parathyroid hormone.
Article
Twelve elderly patients in a rehabilitation ward were given a four-week course of ultra-violet irradiation from a Vitalux lamp. They were compared with 12 controls selected from the same ward. Treatment produced a significant elevation in plasma 25-hydroxy-vitamin D (25OHD) by the end of the second week and concentrations continued to rise over the four-week period. Subject showing the greatest response were those starting with the lowest levels of plasma 25OHD. The findings suggest that ultra-violet irradiation is an effective means of treating vitamin D deficiency in old age and that patients with the greatest degree of deficiency show the greatest response.
Article
We wished to assess the effect of changes in the plasma concentration of 1,25-dihydroxyvitamin D on the plasma elimination half-time for 25-hydroxyvitamin D in man. The turnover of 25-hydroxyvitamin D in plasma was investigated after intravenous doses of the radioactively labelled metabolite had been given to a group of patients (n = 17) with disorders of bone and mineral metabolism before and after oral treatment with calcium or 1,25-dihydroxyvitamin D. Seven patients with post-menopausal osteoporosis, five with hypoparathyroidism, three with hypophosphataemic osteomalacia, one with renal osteodystrophy and one patient with coeliac disease were studied. Intravenous injections of 3H-labelled 25-hydroxyvitamin D were given and plasma elimination half-time assessed over periods of 4-14 days during which frequent measurements of plasma calcium, phosphate, parathyroid hormone, 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were made. Changes in the plasma elimination half-time for 3H-25-hydroxyvitamin D before and after treatment with calcium and 1,25-dihydroxyvitamin D were evaluated by non-parametric statistical analysis. The elimination half-time for 3H-25-hydroxyvitamin D in plasma was significantly shortened by raising the circulating concentration of 1,25-dihydroxyvitamin D. Conversely, in a patient with intestinal malabsorption of calcium, the metabolic clearance of 3H-25-hydroxyvitamin D was prolonged when the concentration of 1,25-dihydroxyvitamin D in plasma was decreased by suppressing secondary hyperparathyroidism with large calcium supplements. In the longer-term studies (n = 10) there was a highly significant inverse relation (r = -0.88, P < 0.001) between the change in the plasma concentration of 1,25-dihydroxyvitamin D and the induced change in the elimination half-time of 3H-25-hydroxyvitamin D. There was also a significant correlation (r = 0.66, p < 0.0025) between the observed fall in the plasma concentration of unlabelled 25-hydroxyvitamin D and the predicted fall calculated from the measured value for the half-time of the 3H-labelled metabolite. In acute studies in patients with post-menopausal osteoporosis (n = 7), enhanced metabolic inactivation of 3H-25-hydroxyvitamin D was detectable within 24 hours of oral administration of 1,25-dihydroxyvitamin D. The effect of 1,25-dihydroxyvitamin D on the catabolism of 25-hydroxyvitamin D can contribute to the development of vitamin D deficiency in many clinical disorders. When the natural supply of vitamin D is limited by sunlight deprivation, a sustained increase in the plasma concentration of 1,25-dihydroxyvitamin D due to primary or secondary hyperparathyroidism will lead to accelerated depletion of vitamin D stores.
Article
Skin tanning is the melanization of the epidermis induced by excessive sunlight exposure. Since melanin absorbs preferentially the wavelengths around 300 nm and the cutaneous synthesis of vitamin D3 is stimulated by the same wavelengths (290 to 320 nm, ultraviolet light B [UVB]), we investigated the effect of tanning on vitamin D3 formation. Vitamin D3 and 25 hydroxyvitamin D (25-OH-D) serum levels were measured during midwinter (untanned state) in seven healthy subjects. Blood was obtained immediately before whole body exposure to UVB in a phototherapy unit, and again 24 hours later. The study was repeated in the same subjects during midsummer (tanned state) using the same UVB dose. Serum vitamin D3 increased in the untanned state from 1.7 +/- 0.4 ng/ml (mean +/- SE) to 11 +/- 1.5 ng/ml following UVB (p less than 0.001). In the tanned state, basal serum vitamin D3 was significantly higher: 9.6 +/- 2.8 ng/ml (p less than 0.04 basal untanned versus basal tanned), and exhibited minimal rise after UVB to 14.3 +/- 4.1 ng/ml (p greater than 0.1 for tanned basal versus post UVB tanned). Tanning was also associated with significantly higher serum 25-OH-D levels: 22.5 +/- 2.9 ng/ml (untanned) versus 36.9 +/- 4.7 ng/ml (tanned) (p less than 0.02). Thus excessive solar exposure produces, besides erythema and tanning, the resetting of the vitamin D3 synthetic mechanism with blunting of the response to UVB.
Article
Several factors could explain the effect of warm, sunny weather on kidney stone formation. To determine the role of sun exposure, we used a light box to administer artificial ultraviolet B radiation during the winter months in New York City. Eleven male stone formers and 7 age- and sex-matched controls received 10 UVB light exposures over a two-week period while maintaining a 400 mg calcium diet. 25-OH vitamin D levels increased significantly (p less than 0.001) in both patients (25.9 +/- 9.8 to 51.6 +/- 14.1 ng/ml) and controls (21.3 +/- 7.1 to 49.6 +/- 3.1 ng/ml). However, 1,25 dihydroxyvitamin D levels rose in the patients (50.8 +/- 14.8 to 55.9 +/- 13.1 pg/ml) but fell (60.1 +/- 6.5 to 49.4 +/- 3.1 pg/ml) in the controls. Only 2 of the 11 patients but all of the controls demonstrated this down regulation of 1,25 dihydroxyvitamin D levels (p less than 0.002). 24,25 dihydroxyvitamin D levels tended to rise in both groups but parathyroid hormone levels were unchanged. There was a trend, which did not reach statistical significance, for parameters of calcium excretion to increase after UVB radiation. 24-hour urinary calcium excretion rose 24% from 140 to 173 mg in the patients and 31% from 113 to 148 mg in the controls. The ratio of calcium/creatinine following a one gram calcium load showed a small increase after UVB radiation from 0.17 to 0.20 in patients and 0.118 to 0.124 in the controls. However, no correlation could be discerned between changes in vitamin D metabolite concentrations and changes in urinary calcium.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
Sunlight has long been recognized as a major provider of vitamin D for humans; radiation in the UVB (290-315 nm) portion of the solar spectrum photolyzes 7-dehydrocholesterol in the skin to previtamin D3, which, in turn, is converted by a thermal process to vitamin D3. Latitude and season affect both the quantity and quality of solar radiation reaching the earth's surface, especially in the UVB region of the spectrum, but little is known about how these influence the ability of sunlight to synthesize vitamin D3 in skin. A model has been developed to evaluate the effect of seasonal and latitudinal changes on the potential of sunlight to initiate cutaneous production of vitamin D3. Human skin or [3 alpha-3H]7-dehydrocholesterol exposed to sunlight on cloudless days in Boston (42.2 degrees N) from November through February produced no previtamin D3. In Edmonton (52 degrees N) this ineffective winter period extended from October through March. Further south (34 degrees N and 18 degrees N), sunlight effectively photoconverted 7-dehydrocholesterol to previtamin D3 in the middle of winter. These results quantify the dramatic influence of changes in solar UVB radiation on cutaneous vitamin D3 synthesis and indicate the latitudinal increase in the length of the "vitamin D winter" during which dietary supplementation of the vitamin may be advisable.
Article
Exposure to solar radiation is increasingly being associated with a risk of cutaneous melanoma, and some risk has also been attributed to exposure to fluorescent lights. The risk of cutaneous melanoma associated with exposure to some sources of artificial ultraviolet radiation was examined in a case-control study in a Scottish population with fairly low exposure to natural ultraviolet radiation. The risk was not significantly or consistently raised for exposure to fluorescent lights at home or at work. The use of ultraviolet lamps and sunbeds, however, was associated with a significantly increased risk (relative risk = 2.9; 95% confidence interval 1.3 to 6.4), and the risk was significantly related to duration of use. The risk was particularly raised among people who have first used [corrected] ultraviolet beds or lamps more than [corrected] five years before presentation (relative risk = 9.1; 95% confidence intervals 2.0-40.6), in whom it was significantly related to cumulative hours of exposure. The risks associated with exposure to ultraviolet lamps and sunbeds remained significant after adjustment for other risk factors for melanoma.
Article
Three previous studies have indicated a seasonal variation in bone mineral content, with values during the summer being 1.7% to 7.5% higher than during the winter. We have examined the seasonal influence on both bone mass, biochemical estimates of bone turnover and vitamin D metabolites in 86 healthy women, aged 29-53 years. All participants were followed up for 2 years with examinations every 6 weeks or 3 months. Bone mineral content in the proximal and distal part of the forearm (single photon absorptiometry) did not reveal any significant seasonal variation, whereas bone mineral density of the lumbar spine (dual photon absorptiometry) indicated that the highest values occurred in winter. None of the biochemical parameters showed any statistically significant cyclical changes. Serum concentrations of 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D3 showed a highly significant seasonal variation, whereas the serum 1,25-dihydroxyvitamin D concentration was virtually unchanged. We conclude that seasonal variation in bone mineral content and bone turnover should not be taken into account when interpreting data from longitudinal studies of healthy pre- and postmenopausal women on a sufficient vitamin D nutriture.
Article
1. The plasma 25-hydroxycholecalciferol [25-(OH)D3] response to measured u.v. irradiation applied thrice weekly for 10 weeks was investigated in normal and in anticonvulsant-treated subjects. 2. Levels of plasma 25-(OH)D3 achieved after u.v. irradiation were similar in both normal and anticonvulsant-treated subjects, suggesting that hepatic microsomal enzyme induction does not lead to low plasma 25-(OH)D3 concentrations. 3. Cholecalciferol was present in plasma of normal subjects in a very low concentrations (< 5·0 nmol/l) and did not increase until plasma 25-(OH)D3 levels exceeded 62·5 nmol/1. 4. Cholecalciferol occurred in significant concentrations in plasma during whole body u.v. irradiation or during oral dosage of 62·5 nmol (1000 i.u) or more daily. 5. Plasma 25-(OH)D3 concentrations reached a steady state after 5–6 weeks of u.v. irradiation or of oral intake within the usual intake range. 6. Cholecalciferol synthesis in skin calculated from the steady-state equation was 0·0015 ± 0·0008 nmol/mJ. 7. Cholecalciferol synthesis in skin was also calculated from the oral dosage required to yield the same plasma 25-(OH)D3 concentration as u.v. irradiation and was 0.0024 ± 0.0018 nmol/mJ. 8. Rates of cholecalciferol synthesis calculated from these data suggest that many of the population of England receive insufficient u.v. irradiation to maintain vitamin D status throughout the year.
Article
The serum concentrations of 25-hydroxycholecalciferol (25OHD3), 25-hydroxyergocalciferol (25OHD2), 24,25-dihydroxyvitamin D (24,25(OH)2D), and 1,25-dihydroxyvitamin D (1,25(OH)2D) were measured in 10 normal subjects every 2 months for 1 year. Parallel seasonal variations were found in serum 25-hydroxycholecalciferol and 24,25-dihydroxyvitamin D reaching maximum values in June. Moreover, a highly significant correlation between changes in these two metabolites was observed (r = 0.89, P less than 0.001). On the other hand, the mean serum 1,25-dihydroxyvitamin D concentration remained constant throughout the year. Our data add further evidence to the tight regulatory mechanism of serum 1,25-dihydroxyvitamin D and the lack of regulatory mechanism of serum 24,25-dihydroxyvitamin D.
Article
The production of vitamin D metabolites in response to ultraviolet irradiation has been studied in 5 control subjects and 8 patients with psoriasis; both groups responded similarly. Significant increases within the normal range were observed for serum 1,25-dihydroxyvitamin D; these increases were negatively related to the initial concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D. Serum 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D increased linearly over the 21 days of study, the production of 25-hydroxyvitamin D being negatively correlated with its own initial concentration. The changes in vitamin D metabolism were accompanied by significant rises within the normal ranges in serum inorganic phosphorus and in urinary calcium. These results indicate the variation of 1,25-dihydroxyvitamin D occurs in vitamin-D-replete adults and that this variation is probably responsible for the observed alterations in calcium and phosphorus metabolism.
Article
The action spectra for delayed erythema and melanogenesis in Caucasian human skin are determined for wavelengths between 250 and 435 nm. The untanned skin of very fair volunteers was observed after single exposures to a range of fluences of monochromatic radiation. At wavelengths longer than 300 nm the two action spectra are indistinguishable, and at wavelengths shorter than 300 nm, they are of similar shape despite a distinct separation. This suggests a common or similar chromophore for initiation of the vascular and pigmentary responses to UV. A broad minimum in the action spectra occurs near 280 nm, a maximum near 296 nm, and for wavelengths longer than 300 nm, increasingly larger fluences of radiation are required to induce delayed erythema and melanogenesis. Between 304 and 334 nm both action spectra exhibit a rapid decrease of almost three orders of magnitude. In contrast, between 334 and 405 nm the spectra decrease by only one order of magnitude, and there is a suggestion of a small maximum at or near 365 nm. Different chromophores, sites of damage, or response mechanisms may be responsible for induction of delayed erythema at these longer wavelengths. After spectral corrections for the optical effects of the stratum corneum, the shape and magnitude of the action spectra are grossly consistent with a mechanism in which DNA is the primary chromophore initiating the response pathways for wavelengths less than 313 nm. Whatever the actual basis for these action spectra may be, they are of practical significance in predicting skin response to sources of ultraviolet radiation.
Article
In a case-control study, we investigated 169 women aged 15-49 years with malignant melanoma notified to the Oxford and South Western cancer registries during the years 1971-1976, together with 507 matched controls. Data about medical, reproductive, drug and smoking histories were obtained both by reviewing general practitioner (GP) records and from the women themselves by postal questionnaires. There was no significant evidence of any overall increase in the risk of melanoma in oral contraceptive (OC) users (data from GP records-ever use vs never use, relative risk (RR) 1.34, 95% confidence limits 0.92-1.96; corresponding data from postal questionnaires-RR 1.13, limits 0.73-1.75). However, although not significant, the risk estimated from data in the postal questionnaires was higher in women who had used OCs for 5 years or more (use greater than or equal to 5 years vs never use, RR 1.57, limits 0.83-3.03). Previously demonstrated risk factors for melanoma, such as fair skin, blond or red hair and Celtic origin were found to be commoner in the cases than in the controls. Data from the Oxford/Family Planning Association contraceptive study were also examined. Unexpectedly there was a strong suggestion of a negative association between OC use and melanoma risk, but the analysis was based on only 12 women with the disease.
Article
The effects of total sunlight deprivation on urinary risk factors for nephrolithiasis and vitamin D metabolism were studied in 20 healthy male subjects. Blood and 24-h urine samples were collected before submarine deployment and 68 days later while still at sea. No subject received sunlight exposure during the test interval. Significant decreases in daily urinary excretion of calcium, uric acid, sodium, sulfate, and phosphorus were found. The relative supersaturation ratio of monosodium urate also fell. There was no change in urinary citrate or urine volume. Mean serum levels of 25-hydroxyvitamin D [25(OH)D] declined from 31 to 19 pg/ml (P < 0.0001), parathyroid hormone increased from 22 to 30 pg/ml (P < 0.0001), and osteocalcin (GLA) increased from 2.7 to 3.3 ng/ml (P = 0.005). Mean serum levels of 1,25 dihydroxy-vitamin D were unchanged. Four subjects had 25(OH)D levels below 10 ng/ml by the end of the submarine patrol. These findings suggest that exposure to the submarine environment produces physiologic changes that decrease the risk for renal stone formation. The data are consistent with the role of vitamin D metabolism in sunlight deprivation and demonstrate that compensatory mechanisms are well established within 68 days.
Article
Determination of the serum or plasma levels of retinol (vitamin A), 25-hydroxyvitamin D, and alpha-tocopherol (vitamin E) are the most frequently used parameters to evaluate status of vitamin A, D, and E, and also to assess the gastrointestinal absorption of the vitamins. We present a simple and sensitive method for simultaneous determination of these vitamins in 0.5 ml human serum or plasma. The vitamins were extracted from serum by methanol/iso-propanol (80/20, v/v) and n-hexane. The n-hexane phase was evaporated and injected to a reversed-phase (C-18) high-performance liquid chromatography system. Elution was performed with methanol/water (85:15, v/v) for 25-hydroxyvitamin D and retinol, and after that by methanol/water (98:2, v/v) for alpha-tocopherol. The eluate was monitored by a UV detector at 265 nm for detection of the vitamins. Baseline separation was obtained for all vitamins, and the system also permitted separate determinations of the D2 and D3 forms of 25-hydroxyvitamin D. The limit of detection and interassay variation for determination in 0.5 ml serum were 6.0 nmol/L and 6.2% for 25-hydroxyvitamin D2, 6 nmol/l and 6.1% for 25-hydroxyvitamin D3, 0.035 mumol/L and 5.0% for retinol, and 1.2 mumol/l and 5.5% for alpha-tocopherol.
Article
The seasonal variation of serum 25-hydroxy vitamin D3 and 1,25-dihydroxy-vitamin D has been investigated. Blood was taken from 27 healthy volunteers, aged 21-44 years old at 3 monthly intervals over a period of 1 year. A scrolling monthly programme with 12 quarterly (3 month) time periods was developed. A summer associated increase in 25-hydroxy vitamin D3 was significantly correlated with but lagged behind by 2 months, the increase in recorded sunlight hours. However, four individuals showed no seasonal rise but maintained constant concentrations throughout the year within the established reference range. Serum 1,25-dihydroxy vitamin D showed marked intra-individual variability with no seasonal pattern although the highest concentration (180 pmol/L) was observed in the winter and no concentration greater than 108 pmol/L in the summer.
Article
It is generally agreed that sunlight exposure is one of the etiologic agents in malignant melanoma of fair-skinned individuals. However, the wavelengths responsible for tumorigenesis are not known, although DNA is assumed to be the target because individuals defective in the repair of UV damage to DNA are several thousandfold more prone to the disease than the average population. Heavily pigmented backcross hybrids of the genus Xiphophorus (platyfish and swordtails) are very sensitive to melanoma induction by single exposures to UV. We irradiated groups of five 6-day-old fish with narrow wavelength bands at 302, 313, 365, 405, and 436 nm and scored the irradiated animals for melanomas 4 months later. We used several exposures at each wavelength to obtain estimates of the sensitivity for melanoma induction as a function of exposure and wavelength. The action spectrum (sensitivity per incident photon as a function of wavelength) for melanoma induction shows appreciable sensitivity at 365, 405, and probably 436 nm, suggesting that wavelengths not absorbed directly in DNA are effective in induction. We interpret the results as indicating that light energy absorbed in melanin is effective in inducing melanomas in this animal model and that, in natural sunlight, 90-95% of melanoma induction may be attributed to wavelengths > 320 nm--the UV-A and visible spectral regions.
The beneficial effects of ultraviolet light on cutaneous vitamin D synthesis, calcium metabolism, and bone formation are well known. Regarding the increasing fear of side effects from ultraviolet B (UV-B), lamps with less energy in the UV-B range have been developed. Two spectra with differences in the emission of UV-B have therefore been evaluated for their influence on calcium metabolism. A group of 24 healthy male volunteers was subdivided into two treatment groups. Group 1 was exposed to lamps with higher energy of total UV-B but less energy at the wavelengths below 300 nm than the lamps used in group 2. All subjects were irradiated ten times within 12 days. Exposure time was 3 min in the first session and time of exposure was increased by 10% in every following irradiation (suberythematous doses only). Before the first irradiation, 3 days after the last exposure, and after 4 more weeks, the serum parameters of bone metabolism were determined by standard laboratory methods. Significantly increased levels of 25-hydroxyvitamin D3 were found in both groups. There was only a slight increase of 1,25-dihydroxyvitamin D3. Parathyroid hormone decreased significantly in group 2 only. The data would suggest beneficial effects on bone metabolism for both regimens. The observed effects were more pronounced when shorter wavelengths (group 2) were applied, although the total energy of UV-B was lower in these lamps.
Article
Seasonal changes in 25-hydroxyvitamin D concentrations were studied in 51 black and 39 white women aged 20-40 y from Boston. Individual measurements were made in February or March (February-March), June or July (June-July), October or November (October-November), and the following February or March (February-March). Samples from the four visits were analyzed in batches at the end of the study. Plasma 25-hydroxyvitamin D was substantially lower in black than in white women at all the time points, including February-March when values were lowest (30.2 +/- 19.7 nmol/L in black and 60.0 +/- 21.4 nmol/L in white women) and June-July when they were highest (41.0 +/- 16.4 nmol/L in black and 85.4 +/- 33.0 nmol/L in white women). Although both groups showed seasonal variation in 25-hydroxyvitamin D concentrations, the mean increase between February-March and June-July was smaller in black women (10.8 +/- 14.0 nmol/L compared with 25.4 +/- 29.8 nmol/L in white women, P = 0.006) and their overall amplitude of seasonal change was lower (P = 0.001). Concentrations of serum parathyroid hormone in February-March were significantly higher (P < 0.005) in black women (5.29 +/- 2.32 pmol/L) than in white women (4.08 +/- 1.41 pmol/L) and were significantly inversely correlated with 25-hydroxyvitamin D in blacks (r = -0.42, P = 0.002) but not in whites (r = -0.19, P = 0.246). Although it is well established that blacks have denser bones and lower fracture rates than whites, elevated parathyroid hormone concentrations resulting from low 25-hydroxyvitamin D concentrations may have negative skeletal consequences within black populations.