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Vitamin D status and its adequacy in healthy Danish perimenopausal women: relationships to dietary intake, sun exposure and serum parathyroid hormone

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  • Danish Health Authority

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We conducted this study to assess the prevalence of vitamin D insufficiency in a population of normal perimenopausal women, to examine the influence of sun exposure and vitamin D intake on the concentration of 25-hydroxyvitamin D (25OHD) and to examine the association between parathyroid hormone (PTH) and 25OHD. A total of 2016 healthy women aged 45-58, who had recently undergone a natural menopause, were enrolled over a 2.5-year period in the Danish Osteoporosis Prevention Study. A marked seasonal fluctuation of 25OHD was seen, with an abrupt rise in June and high values until October. The fluctuation could be related to number of hours of sunshine per month with a two months time lag. Dietary vitamin D intake, vitamin supplementation, sunlight exposure, and use of sun-bed were all significantly related to 25OHD concentrations. Sun exposure seemed to contribute the most. The overall prevalence of vitamin D deficiency (defined as serum ) was 7 %. However, in the subgroup avoiding direct sunshine and abstaining from vitamin D supplementation 32.8 % were vitamin D deficient in the winter-spring period. Although mean PTH was increased in the group with low serum 25OHD, PTH was not a sensitive marker of hypovitaminosis D in the individual, as only 16 % of those with vitamin D deficiency had PTH levels above normal range. Thus, we have shown, that healthy middle-aged Danish women are prone to vitamin D insufficiency in the winter-spring period, if they avoid sun exposure in the summer period and abstain from vitamin D supplementation.
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Vitamin D status and its adequacy in healthy Danish
perimenopausal women: relationships to dietary intake,
sun exposure and serum parathyroid hormone
Christine Brot
1
*, Peter Vestergaard
2
, Niels Kolthoff
3
, Jeppe Gram
4
, Anne P. Hermann
2
and
Ole H. Sùrensen
1
1
Osteoporosis Research Clinic, Dep 545, Copenhagen University Hospital Hvidovre, Kettegaard Alle
Â
30,
DK- 2650 Hvidovre, Denmark
2
Department of Endocrinology and Metabolism, Aarhus Bone and Mineral Research Group, Aarhus Amtssygehus,
Tage Hansens Gade 2, DK-8000 Aarhus C, Denmark
3
Department of Clinical Physiology, Hilleroed Hospital, Helsevej 2, DK- 3400 Hilleroed, Denmark
4
Department of Endocrinology, Odense University Hospital, Sdr. Boulevard 29, DK-5000 Odense C, Denmark
We conducted this study to assess the prevalence of vitamin D insufficiency in a population of
normal perimenopausal women, to examine the influence of sun exposure and vitamin D intake
on the concentration of 25-hydroxyvitamin D (25OHD) and to examine the association between
parathyroid hormone (PTH) and 25OHD. A total of 2016 healthy women aged 45±58, who had
recently undergone a natural menopause, were enrolled over a 2´5-year period in the Danish
Osteoporosis Prevention Study. A marked seasonal fluctuation of 25OHD was seen, with an
abrupt rise in June and high values until October. The fluctuation could be related to number of
hours of sunshine per month with a two months time lag. Dietary vitamin D intake, vitamin
supplementation, sunlight exposure, and use of sun-bed were all significantly related to 25OHD
concentrations. Sun exposure seemed to contribute the most. The overall prevalence of vitamin
D deficiency (defined as serum 25OHD , 25 nmol=l) was 7 %. However, in the subgroup
avoiding direct sunshine and abstaining from vitamin D supplementation 32´8 % were vitamin
D deficient in the winter±spring period. Although mean PTH was increased in the group with
low serum 25OHD, PTH was not a sensitive marker of hypovitaminosis D in the individual, as
only 16 % of those with vitamin D deficiency had PTH levels above normal range. Thus, we
have shown, that healthy middle-aged Danish women are prone to vitamin D insufficiency in the
winter±spring period, if they avoid sun exposure in the summer period and abstain from vitamin
D supplementation.
25-Hydroxyvitamin D: Parathyroid hormone: Vitamin D deficiency
Introduction
During the last decade many efforts have been aimed at
redefining nutritional adequacy, in order to reduce the risk
of chronic disease in addition to more traditional evidence
of sufficiency, such as absence of classical deficiency
diseases. Not least vitamin D has attracted attention in view
of the worldwide epidemic of osteoporosis and the
overwhelming evidence of the high prevalence of defi-
ciency in elderly populations (McKenna, 1992).
Vitamin D is essential for normal calcium and bone
metabolism. The circulating concentration of 25-hydroxy-
vitamin D (25OHD) is considered a good marker of vitamin
D status as it represents the cumulative effects of dietary
intake of vitamin D and exposure to sunlight (Holick,
1996). However, defining the optimal level of 25OHD,
which would ensure development and maintenance of a
healthy skeleton has proven not to be an easy task. The
threshold for vitamin D deficiency is generally considered
to be at a serum 25OHD level below 25 nmol/l (10 ng/ml)
(Parfitt et al. 1982). However, there is increasing evidence
that more subtle alterations in calcium and bone metabo-
lism occur at 25OHD levels, which were earlier thought to
be adequate. These unfavourable changes include impaired
calcium absorption (Kinyamu et al. 1997; Zittermann et al.
1998), slight elevations in serum parathyroid hormone
DOI: 10.1079/BJN2001345British Journal of Nutrition (2001), 86, Suppl. 1, S97±S103
q The Authors 2001
Abbreviations: FSH, follicle-stimulating hormone; 25OHD, 25-hydroxyvitamin D; PTH, parathyroid hormone.
* Corresponding author: Dr Christine Brot, The Danish Veterinary and Food Administration, Mùrkhùj Bygade 19, DK-2860 Sùborg, Denmark, fax
145 33 95 66 96, email cxb@fdir.dk
(PTH) (Krall et al. 1989; Kinyamu et al. 1998) leading to
increased bone turnover and accelerated bone loss (Daw-
son-Hughes et al. 1991; Chapuy et al. 1996). The cut-off
level between this state of insufficiency and the replete
state remains to be defined, but it has been stated to probably
exceed 50 nmol/l (20 ng/ml) by McKenna & Freaney
(1998). Among younger adults, the prevalence of vitamin
D deficiency has been reported to be low in the USA
(McKenna, 1992; Kinyamu et al. 1997), quite common in
the southern part of Europe (Burnand et al. 1992; Chapuy
et al. 1997), and moderate in Scandinavia (Lund &
Sùrensen, 1979; Aksnes et al. 1988; Landin-Wilhelmsen
et al. 1995). The prevalence of vitamin D insufficiency is
obviously dependent on the limit chosen, but is likely to be
very common.
How much vitamin D we must produce or ingest to
achieve the optimal concentration of 25OHD is another key
question. The main source of vitamin D is exposure to
sunlight, but a number of factors, such as latitude, season,
time of the day, use of topical sunscreens, influence the
cutaneous production of vitamin D (Holick, 1996). At the
latitude of Denmark (54±588N), no cutaneous vitamin D
production occurs from October to April (Webb et al.
1988). During that period, maintenance of vitamin D level
is dependent on oral vitamin D intake and on the stores of
vitamin D built up during the previous summer. In
Denmark, there is no food fortification with vitamin D.
However, half the population takes vitamin supplementa-
tion either all year, or at least during wintertime (Lund &
Sùrensen, 1979; Andersen et al. 1995). From the Danish
national dietary survey it appears that the average vitamin
D intake was 3´4 mg daily, and only 10 % of the adult
population had vitamin D intakes at or above the RDA
(5 mg per day) (Andersen et al. 1995).
There is little scientific information relating vitamin D
intake and sun exposure to vitamin D status as determined
by serum 25OHD and PTH concentrations in large adult
population groups.
The present study was conducted to assess the pre-
valence of vitamin D insufficiency in a population of
normal perimenopausal women, to estimate the relative
influences of sun exposure and vitamin D intake on the
concentration of 25OHD and to examine the relationship
between PTH and 25OHD.
Material and methods
Subjects
The present study is part of an ongoing long-term
multicentre trial on hormone replacement therapy, the
Danish Osteoporosis Prevention Study (DOPS) (Mosekilde
et al. 1999). A total of 2016 healthy perimenopausal
Caucasian women were recruited from the general com-
munity by direct mailing. The inclusion criteria were (1)
intact uterus, age 45±58 years and 3±24 months past
last menstrual bleeding or perimenopausal symptoms
(including menstrual irregularities) and elevated serum
follicle stimulating hormone (FSH); (2) hysterectomized,
age 45±52 years and elevated serum FSH. The following
exclusion criteria were applied: (1) osteoporotic fractures
of the spine verified by X-ray; (2) metabolic bone disease;
(3) current oestrogen use, but former use of up to 3 months
was accepted; (4) former treatment with corticosteroids for
a period longer than 6 months; (5) presence of hyper- and
hypothyroidism; (6) any chronic disease if newly diagnosed
or out of control; (7) liver disease or unstable cardiac
disease; (8) current or past malignant disease; (9) ever
hospitalized due to ethanol abuse or drug addiction; (10)
a history of deep thrombophlebitis and stroke. Women
fulfilling these criteria were biochemically screened,
ensuring that all had serum concentrations of ionized
calcium, alanine aminotransferase, creatinine and thyroid
stimulating hormone within normal reference limits. The
inclusion period lasted 2´5 years, from November 1990 to
March 1993. The present study is a cross-sectional study of
baseline data.
Biochemical measurements
During the first visit, blood samples were obtained from the
subjects under fasting conditions between 8 and 11 a.m.
Serum was stored at 2808C until analysis and had a single
thaw at time of analysis. Serum levels of 25OHD were
measured in one laboratory by a competitive assay using
rachitic rat binding protein (Lund & Sùrensen, 1979). The
lower detection limit was 12´5 nmol/l. The intra- and
interassay precisions were 8´3 % and 10´2 %, respectively.
Vitamin D
2
and D
3
metabolites were measured together by
the method.
Serum intact PTH was measured with Immulite intact
PTH immunoassay kit in 1097 women (i.e. those
participating in the centres of Aarhus and Copenhagen).
The lower limit of detection was 0´3 pmol/l. The intra- and
interassay precisions were 5´4±7´0 % and 5´0±5´5 %,
respectively. The normal range had been established in
196 healthy blood donors (both genders, age 20±60 years)
and was 1´3±7´6 pmol/l.
Serum bone specific alkaline phosphatase was analysed
by lectin precipitation, intra-assay variation 8 %, interassay
25 % (Brixen et al. 1989).
Vitamin D intake
Dietary vitamin D intakes were estimated by using diet
records in 1907 subjects (94´6 % of the cohort). The study
started up with 4-day diet records, which were later
extended to 7-day records to improve the precision of the
assessments of nutrients intake. In the whole population,
626 (32´8 %) performed diet records for four consecutive
days, 1272 (66´7 %) performed 7-day records, and nine
participants (0´5 %) performed either 2, 3, 5 or 6-day
records. The 4-day records included one weekend day
(either from Wednesday to Saturday or from Sunday to
Wednesday). Participants recorded all foods and beverages
that were consumed daily in an open-ended form,
estimating quantities in household measures. They received
oral and written instructions and the importance of keeping
accurate records was explained. A trained dietitian
reviewed the records with the majority of the participants
so as to obtain additional information to improve the
estimation of food intake. A small number of participants
S98 C. Brot et al.
did not encounter the dietitian, but filled in and mailed the
forms. These participants were contacted by telephone if
necessary to clarify unclear matters. All food records were
analysed for nutrients intake by using Dankost Software
version 1.3b, a program based on the official Danish food
table (Mùller, 1989). There was a small difference in the
estimates of vitamin D intake between the 4-day and the 7-
day records: mean vitamin D intake was 2´9 mg and 3´1 mg,
respectively P , 0´01: Because of the large sample size,
the difference of 0´2 mg is significant, but it is not clinically
relevant, for which reason data were pooled.
The subjects were asked to state whether or not they
took vitamin D supplementation for at least half of the
year (in Denmark, the majority of dietary supplements
that include vitamin D contain 200 IU, which equals 5 mg
cholecalciferol).
UV-exposure
In each of the four centres, all the subjects were
interviewed by the same two doctors. The degree of
sunlight exposure was assessed by asking the subjects a
simple question which enabled them to be categorized into
three groups: `How frequently do you expose yourself to
sunlight lightly dressed, either with the purpose of getting
sun-tanned or during the course of various outdoor
activities like sport or gardening?' The interviewer selected
which one of the following categories most accurately
described their behaviour: `Never' meant that the person
preferred not to stay in direct sunlight, but, as we are
dealing with normally active middle-aged persons, casual
sun exposure occurred in daily life; `Occasionally' meant
that the person sometimes spent time outdoors in the
sunshine; `Regularly' meant that the person quite often
intendedly exposed themselves to sunshine. The question
focused on sun exposure because direct solar radiation is
the major source of UVB, even though a minor part of the
UVB radiation is scattered around.
The use of artificial `sun-beds' was registered no 0;
yes 1:
Data on the number of hours of bright sunshine in each
of the inclusion months were obtained from the Danish
Institute of Meteorology.
Statistical analysis
Serum 25OHD was logarithmically transformed in order to
achieve a normal distribution. The relationship between
logarithmated serum 25OHD as dependent variable and
daily intake of vitamin D in foods, vitamin supplementation
(coded as: 0, no supplements; 1, use of supplements at least
for some of the year), use of solarium (yes/no), and whole
body exposure to sunlight (coded as a dichotomous
variable: 0, `never'; 1, `occasionally' or `regularly') as
independent variables were examined using multiple
regression analysis with all independent variables entered
into the model. Linear and non-linear regression analysis
was performed between PTH and serum 25OHD. All
P-values are two-tailed. Significance limit was P , 0´05:
The analyses were performed with the Fastat Statistics
Package for Macintosh.
The study was approved by the Ethics Committee of
Copenhagen, and written informed consent was obtained
from all subjects.
Results
Determinants of serum 25OHD
Sixty-three percent of the population took vitamin supple-
mentation at least during wintertime. This group had a
Fig. 1. Relationship between hours of sunshine and serum 25OHD. B, Hours of sunshine; X, 25OHD (ng/ml).
S99Vitamin D status in middle-aged Danish women
higher mean serum 25OHD than the rest: 66´0 versus
57´5 nmol/l. The mean difference (95 % CI) was 8´5 nmol/l
(6´3±10´8).
There was a seasonal fluctuation of serum 25OHD, with
an abrupt rise in concentration in June and highest values
from June to October. This fluctuation could be related to
number of hours of sunshine, with a 2 months time lag
(Fig. 1). The impact of sun exposure on 25OHD is shown in
Fig. 2, which illustrates the changes in those (37 %) who
did not take vitamin supplementation. Low mean serum
25OHD levels were seen during the whole year among
those reporting never to sunbathe. A modest seasonal
variation was seen in this group, as an expression of the
casual sun exposure, which invariably occurs in free-living
persons. Higher 25OHD levels than the rest of the
population were observed all year round among those
reporting regular exposure to sunshine with marked
seasonal variation.
The relative contributions of UV exposure and oral
vitamin D intake in determining serum 25OHD were
further quantified in multiple regression analysis, the
results of which are shown in Table 1. Increasing intake
of vitamin D in foods, active sunbathing, use of solarium,
and use of vitamin supplements all significantly increased
mean annual serum vitamin D. Active sunbathing seemed
to contribute the most to high vitamin D status (27´6 %
more with active sunbathing) whereas vitamin D in foods
contributed relatively little (9´0 % more per 5 mg vitamin
D per day). During the summer±autumn period dietary
intake lost its significance.
Prevalence of hypovitaminosis D
Overall, 7 % of the population had 25OHD levels
, 25 nmol=l (3 % during summer and autumn and 11 % in
winter and spring). Only one subject had 25OHD below
detection limit. The prevalence of vitamin D insufficiency,
defined as 25OHD concentrations below 50 nmol/l was
39´7 % (58´9 % during summer and autumn and 23´0 % in
winter and spring). However, 32´8 % of those avoiding
direct sunshine and not taking vitamin pills had serum
25OHD levels , 25 nmol=l during winter and spring, and
79´7 % had serum 25OHD levels below 50 nmol/l
(Table 2).
PTH and bone specific alkaline phosphatase
An inverse relationship exists between PTH and 25OHD
(Pearsons correlation r 20´14; P , 0´001: Thus, mean
PTH increased with decreasing 25OHD concentrations. In
the subgroup with 25OHD concentrations , 25 nmol=l;
Table 1. Factors associated with serum 25-hydroxyvitamin D
Variable² Regression coefficient b (SE)
Increases in
25OHD³ (%) T
The whole population
Dietary vitamin D intake (mg/day) 0´018 (0´004)** 1´8 per mg 4´47
Use of vitamin supplements (1: yes, 0: no) 0´146 (0´023)** 15´7 higher for `yes' 6´39
Whole body exposition to sunlight (1: yes, 0: no) 0´244 (0´032)** 27´6 higher for `yes' 7´61
Use of sun-bed (1: yes, 0: no) 0´124 (0´026)** 13´2 higher for `yes' 4´87
Subpopulation included from December to May
Dietary vitamin D intake (mg/day) 0´025 (0´006)** 2´5 per mg 4´32
Use of vitamin supplements (1: yes, 0: no) 0´183 (0´031)** 20´1 higher for `yes' 5´84
Whole body exposition to sunlight (1: yes, 0: no) 0´207 (0´045)** 23´0 higher for `yes' 4´55
Use of sun-bed (1: yes, 0: no) 0´177 (0´035)** 19´4 higher for `yes' 4´99
Subpopulation included from June to November
Dietary vitamin D intake (mg/day) 0´008 (0´005) 0´8 per mg 1´72
Use of vitamin supplements (1: yes, 0: no) 0´076 (0´028)* 7´9 higher for `yes' 2´71
Whole body exposition to sunlight (1: yes, 0: no) 0´293 (0´038)** 34´0 higher for `yes' 7´63
Use of sun-bed (1: yes, 0: no) 0´090 (0´005)* 9´4 higher for `yes' 2´90
*P , 0´01; **P , 0´001:
² Analysed in multiple regression model containing these variables and with logarithm of serum 25-hydroxyvitamin D as dependent variable.
³ The regression coefficients b has been antilogarithmated to fit actual serum vitamin D value. The figures express percentage change in serum 25OHD.
Fig. 2. Seasonal fluctuation of serum 25OHD according to frequency
of sun exposure. B, Regular sun exposure; V, occasional sun
exposure; X, avoiding direct sun exposure.
S100 C. Brot et al.
mean PTH was 5´2 pmol/l, corresponding to an increase of
1´2 pmol/l (95 % CI: 0´6±1´9) when compared to the rest
of the study group.
In an attempt to further characterize the relationship
between PTH and 25OHD, we performed linear and non-
linear regression analyses:
Linear: PTH 4´6341 2 0´0235 25OHD
Logarithmic: PTH 6´1206 2 0´6681 ln25OHD
Cubic: PTH 5´4406 2 0´0994 25OHD 1 0´0018
25OHD
2
2 1 10
25
25OHD
3
Power: PTH 5´3665 25OHD
20´1319
Exponential: PTH 3´9968 e
20´0046
Even though some of the models fitted well, the
predictive value of the models was not very high, as they
explained only 1´2±2´7 % of the total variation.
The variability of PTH increased with decreasing
25OHD concentrations. Thus, only 16´2 % of those with
25OHD , 25 nmol=l had elevated PTH values (Table 3).
Overall, 4´7 % had PTH value above normal range, the
majority of them having 25OHD values of 25±75 nmol/l.
In fact, only when 25OHD levels exceeded 100 nmol/l,
were all PTH measurements within the normal range.
No relationship could be demonstrated between 25OHD
and bone specific alkaline phosphatase.
Discussion
Our data confirm the well-established predominant influ-
ence of sun exposure on vitamin status (Holick, 1996). At
the latitude of Denmark (54±588N), no cutaneous vitamin
D synthesis occurs during 6±7 months of the year, making
great demands on the vitamin D stores. The 2 months
timelag between the increase in number of hours of
sunshine and the rise in serum 25OHD concentration might
be explained by the fact that in Denmark temperatures are
still often too low for light clothing or sunbathing in April
and May. Holick (1996) has estimated that for elderly
people, the exposure of hands, face, and arms to
suberythemal doses of radiation (10±15 min between 11
am and 2 pm) two to three times a week in the summer
would satisfy a requirement of 400 IU/day of vitamin D. It
appears from our results, with the limitations of a cross-
sectional study, that it requires regular sun exposure during
the summer to build up sufficient stores to ensure adequate
vitamin D status during winter and spring, even in younger
persons. Use of artificial sun-beds seemed to have the same
predictive effect on serum 25OHD as vitamin supplemen-
tation, although it is usually held that sun-beds contribute
marginally to endogenous production of vitamin D, as they
transmit only small amounts of ultraviolet B radiation.
However, this estimate may be biased as the women using
sun-beds regularly are also those who sunbathe most
frequently. We do not have information regarding use of
sunscreens, which are known to impair cutaneous vitamin
D production, but data were gathered in the early 1990s
before the campaigns recommending use of sunscreens.
That the influence of supplementary vitamin D in this
study seemed to have higher impact per microgram on
serum 25OHD than dietary vitamin D, might be due to the
use of short-term diet records, resulting in imprecise
estimates of dietary vitamin D intake.
The overall prevalence of vitamin D deficiency of 7 %
(3 % during summer and 11 % during winter) is in
accordance with earlier Scandinavian reports (Lund &
Sùrensen, 1979; Aksnes et al. 1988; Landin-Wilhelmsen
et al. 1995). However, the subgroup avoiding direct sun
exposure attracts attention; during late wintertime and
spring 32 % had serum 25OHD concentration below
25 nmol/l (10 ng/ml) and 90 % below 62´5 nmol/l
(25 ng/ml). These middle-aged women are, in our study
healthy, living a normal life, and are therefore exposed to
Table 2. Prevalence of low vitamin D status during winter and spring according to sun exposure and vitamin supplementation
Behavioural pattern:
Avoiding direct sunshine* Occasional sun exposure* Regular sun exposure*
No vitamin
supplement
+vitamin
supplement
No vitamin
supplement
+vitamin D
supplement
No vitamin
supplement
+vitamin
supplement
Mean serum 25OHD (nmol/l) 36´5 45´3 41´5 49´3 53´5 62´3
Percentage of the cohort 6´6 % 7´6 % 16´6 % 28´4 % 13´9 % 26´9 %
Percentage of the subgroups with:
Serum 25OHD , 25 nmol=l 32´8 % 12´9 % 17´6 % 10´7 % 9´8 % 2´8 %
Serum 25OHD , 50 nmol=l 79´7 % 72´9 % 75´2 % 57´9 % 53´5 % 39´1 %
Mean serum intact PTH (pmol/l) 5´2 4´4 4´3 3´9 3´9 3´8
To convert values for 25-hydroxyvitamin D (25OHD) to ng/ml, multiply by 0´4.
* The dietary intake of vitamin D did not differ between the groups and was on average 3´1 mg per day.
Table 3. Prevalence of PTH measurements above normal range according to serum 25-
hydroxyvitamin D levels
Serum 25OHD ,25 nmol/l 25±50 nmol/l .50 nmol/l
Percentage of the population 6´7 % 33´2 % 60´1 %
Mean serum intact PTH (pmol/l) 5´2 4´2 3´8
Percentage with elevated PTH levels 14´9 % 5´4 % 2´8 %
To convert values for 25-hydroxyvitamin D (25OHD) to ng/ml, multiply by 0´4.
S101Vitamin D status in middle-aged Danish women
some UV radiation on face and hands during daily life
activities. Therefore, a seasonal variation is also found in
this group, although of modest amplitude. Even though it is
only a minority of the total cohort, it is worrying that their
vitamin D status is so low. Their way of life is probably
similar to the majority of the best-functioning elderly. For
many older people, the development of vitamin D
deficiency has often been attributed to the lack of sunlight,
rather than to the effects of ageing (Egsmose et al. 1987).
In accordance with this, the SENECA study found 25OHD
levels among 70±76-year-old persons comparable to the
values in our subgroup that avoided sun exposure (van der
Wielen et al. 1995).
Several authors have attempted to delimit the boundary
between vitamin D insufficiency and sufficiency. In a
number of cross-sectional studies, performed among both
young and elderly age groups and with wide geographic
dispersion, the threshold serum 25OHD concentration
below which mean PTH level increased ranged from
37´5 nmol/l (15 ng/ml) to 110 nmol/l (44 ng/ml) (Krall
et al. 1989; Chapuy et al. 1997; Dawson-Hughes et al.
1997; Thomas et al. 1998). Malabanan et al. (1998) have
shown that 50 nmol/l (20 ng/ml) was the minimal 25OHD
concentration at which PTH no longer decreased when
vitamin D supplementation was administered. When using
the value of 50 nmol/l as threshold, the majority of our
subjects could be considered to be in a state of
insufficiency at least in the winter period. Whether or
not, values below this level for 6 months a year, so-
called transient insufficiency, are harmful when repeated
for many years remains unclear. As long as there is a
lack of long-term longitudinal studies of the conse-
quences of various levels of serum 25OHD, we will have
to rely on recommendations for adequate vitamin D
levels based on presumptions from well-known condi-
tions of deficiency. This study, which is planned to be
continued over 20 years, will hopefully bring us closer to
an answer.
PTH and 25OHD were inversely related and the group
with serum 25OHD concentrations below 25 nmol/l had
31 % increased mean PTH, which corresponds to approxi-
mately 0´5 SD. The inverse relationship between 25OHD
and PTH is of particular interest, because PTH is a potent
bone-resorbing agent and even slight elevations in serum
PTH (i.e. in the same order of magnitude as our findings) is
associated with increased bone turnover and accelerated
bone loss, which may be prevented by vitamin D
supplementation (Dawson-Hughes et al. 1991; Chapuy
et al. 1996).
However, it is undoubtedly important to consider not
only the mean value but the proportion of subjects in whom
the PTH level is above normal range. In the daily clinical
situation, PTH measurements are often used to identify the
degree of hypovitaminosis D. Hyperparathyroidism is
commonly seen among population groups who have had
persistently very low serum 25OHD levels for some time,
like frail elderly people or immigrants (Egsmose et al.
1987; Henriksen et al. 1995). In our material, where
seasonal fluctuation was seen among all groups, most of the
women with low serum 25OHD values were only deficient
for part of the year. This might explain why only a
relatively small proportion of them had secondary hyper-
parathyroidism (15 % of those with serum 25OHD below
25 nmol/l). Furthermore, the majority of the women with
serum PTH levels above the normal range had serum
25OHD concentrations of 25±100 nmol/l. In free-living
elderly people in the USA, and in a large sample of normal
middle-aged French men and women, normal PTH levels
have also been registered in the majority of subjects with
low serum 25OHD levels (Chapuy et al. 1997; Kinyamu
et al. 1998; Gallagher et al. 1998). Therefore, PTH does not
seem to be a sensitive marker of vitamin D deficiency in
the single person. Nor is bone-specific alkaline phospha-
tase, as we found no relationship between serum 25OHD
and this parameter.
In conclusion, we have shown in this cross-sectional
study, that healthy middle-aged Danish women are prone to
vitamin D insufficiency in the winter±spring period, if they
avoid sun exposure in the summer period and abstain from
vitamin D supplementation. With few very simple ques-
tions about sunbathing habits and vitamin supplementation,
which are practicable in every doctor's surgery, we were
able to identify a group of whom one-third were vitamin D
deficient and 90 % could be considered as in a state of
insufficiency during the winter±spring season. Being able
to select patients at risk by easy means is of great
importance both for the practitioner and for health
authorities.
It also appears from our results that although PTH and
25OHD were inversely related, PTH measurement cannot
be used to diagnose hypovitaminosis D in the individual.
Acknowledgements
The authors thank Dr Lars Bjùrn Jensen, Dr Bo
Abrahamsen, and Dr Pia Eiken for collecting data for the
study. They also thank Dr Lars Ovesen, the Danish
Veterinary and Food Administration, for reading and
discussing the manuscript. They also gratefully acknow-
ledge the statistical assistance of Lene Theil Skovgaard,
associate professor at the department of biostatistics of the
University of Copenhagen.
The study was financed by the Karen Elise Jensens
Foundation.
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S103Vitamin D status in middle-aged Danish women
... We searched the literature to find studies that report monthly 25(OH)D concentration. We found 15 studies [11,[17][18][19][20][21][22][23][24][25][26][27][28][29][30] and extracted average monthly 25(OH)D concentration. We also calculated mean 25(OH)D for each month in the UK Biobank dataset (data not shown). ...
... We also calculated mean 25(OH)D for each month in the UK Biobank dataset (data not shown). Studies were classified as (A) healthy/population-based cohorts [11,17,20,21,[23][24][25][26], (B) disease cohorts [18,19,22], or (C) laboratory samples/database [27][28][29][30], and analyzed separately. Based on the country the study was conducted in, we used average monthly CW-D-UVB data for the corresponding capital city from our file (except Faroe Islands where the mean between Oslo and Reykjavik was used). ...
... The correlation was weaker in cohorts of diseased individuals (β-coeff = 0.065, r 2 = 0.33, p-value = 0.00024, Figure 5B) and in laboratory datasets (β-coeff = 0.042, r 2 = 0.38, p-value = 9.23 × 10 −9 , Figure 5C). [11,17,20,21,[23][24][25][26], (B) disease cohorts [18,19,22] or (C) laboratory samples/database [27][28][29][30]. Included studies are briefly described in Table S2. ...
Article
Full-text available
Dermal synthesis, following sun exposure, is the main source of vitamin D. This study characterizes ambient UVB radiation relevant for vitamin D production in Europe. A biological weighing function was applied to data from the Tropospheric Emissions Monitoring Internet Service (TEMIS) for 46 capital cities over an 18-year period (2004–2021) to isolate wavelengths relevant for vitamin D production (D-UVB). Cumulative and weighted D-UVB (CW-D-UVB) were calculated to approximate seasonal vitamin D accumulation and diminution. Monthly 25(OH)D concentration measurements were extracted from published reports. All data were analyzed by location and time. Despite a moderate latitudinal range (35–64° N), we observed large—up to five-fold—regional differences: the highest mean diurnal D-UVB dose of 5.57 kJ/m2 (SD = 3.55 kJ/m2) was observed in Nicosia (Cyprus) and the lowest in Reykjavik (Iceland, 1.16 ± 1.29 kJ/m2). Seasonal differences in diurnal D-UVB dose were even more pronounced, with a median 36-fold difference between annual peak and trough depending on a location (range: 10- to 525-fold). The mean duration of “vitamin D winter” was 126 days but varied widely (4 to 215 days). Monthly CW-D-UVB and 25(OH)D changes were very strongly correlated: the changes in 25(OH)D concentration increased by 12.6 nmol/L for every 100 kJ/m2 increment of CW-D-UVB in population-based studies (r2 = 0.79, p-value = 1.16 × 10−37). Understanding the differences in D-UVB radiation can help understand determinants of vitamin D status and guide region- and season-specific safe and effective sunlight exposure recommendations and vitamin D supplementation guidelines.
... All willing women between the ages of 44 and 65 were included in the study. For the final analysis, the exclusion criteria, summarised according to (33) and supplemented, were: 1) confirmed osteoporosis; 2) current oestrogen therapy (prior oestrogen therapy was not an exclusion criterion if >3 months have elapsed since the last dose); 3) treatment with corticosteroids in the previous 12 months; 4) treatment of hyperthyroidism or hypothyroidism in the previous 12 months; 5) any new or unregulated chronic disease (e.g. unregulated diabetes); 6) malignant diseases at any time in life; 7) hysterectomy was not an exclusion criterion; 8) health conditions associated with vitamin D deficiency (malabsorption, chronic inflammatory bowel disease, gastrointestinal resection, liver disease, acute gallbladder disease, chronic kidney disease grade 3 to 5); 9) institutionalisation and poor physical mobility; 10) excessive vitamin D intake (serum 25(OH)D3 >250 nmol/L). ...
... .2478/sjph-2023-0005 Zdr Varst. 2023;62(1):[30][31][32][33][34][35][36][37][38] ...
Article
Full-text available
Introduction For almost nine decades, the fortification of foods with vitamin D has been proven effective in preventing rickets. This study aims to build and economically evaluate a fortification model based on egg biofortification and milk (including yoghurt) fortification. Methods A cross-sectional study was carried out between 1. March and 31. May 2021. Three hundred and nineteen healthy women from the Central Slovenian region aged between 44 and 65 were recruited for the study, with 176 participants included in the final analysis. For the fortification model calculations, the vitamin D contents of unenriched milk (including yoghurt) and eggs were replaced by enriched foods containing vitamin D. The economic evaluation was done using available drug and food supplement prices. Fortification costs were calculated using vitamin D prices provided by suppliers. Results Mean vitamin D intake from food was 2.19±1.34 µg/d. With fortification Model 1 (enriched eggs), it would be: 6.49±4.45 µg/d, and with Model 2 (enriched eggs and milk): 10.53±6.49 µg/d. Without fortification, none of the participants would reach a daily vitamin D intake >10 µg. With fortification Model 1 (egg fortification), 15.3% would reach >10 µg and with Model 2 (egg and milk fortification) 46.2% would reach >10 µg. The economic comparison of the annual cost of 10 µg vitamin D/d/person was EUR 6.17 for prescription drugs, EUR 6.37 for food supplements, EUR 0.09 for direct milk fortification and EUR 0.12 for egg biofortification with vitamin D. Conclusions Egg and milk (including yoghurt) fortification could cost-effectively increase vitamin D intake in the Slovenian population of women between 44 and 65 by almost five-fold, and could significantly lower the prevalence of vitamin D deficiency. Additional research and changes to legislation are needed before this can be introduced.
... The study was set up as a cross-sectional study to estimate the level of vitamin D in serum from newly weaned sows in organic Danish herds located at 55-57 • N during the summer of 2020. We chose to sample in August because high vitamin D levels were observed in humans in Denmark during this month [18]. ...
... We investigated the vitamin D status in free-range sows at the time of expected highest level, i.e., July/August, but we have no data at the expected lowest level, i.e., February/March [18]. However, we do have information of such comparison for the content of 25(OH)D 3 and vitamin D 3 in shoulder meat from Danish, free-range pigs slaughtered in August (2018) and March (2019) [38]. ...
Article
Full-text available
Vitamin D is essential for sow health and productivity. Standard sow feed is therefore supplemented with vitamin D3 or 25-hydroxyvitamin D3 (25(OH)D3). However, it is uncertain whether the levels achieved are adequate for optimal performance. Currently, information on serum levels of vitamin D in pigs reared under both indoor and outdoor conditions is lacking. In August 2020, we obtained blood samples from 97 organic newly weaned sows housed outdoors during pregnancy and farrowing and used these to test for vitamin D in serum. The average concentration was 67 ± 16 ng 25(OH)D3/mL with a range of 32 to 134 ng 25(OH)D3/mL. The vitamin D3 content was 21 ± 7 ng/mL, ranging from 9 to 48 ng/mL. The average number of hours of sun from June to August was 7.0 ± 0.5 h/day. Parity, farm and body condition score did not significantly affect serum levels of 25(OH)D3.
... These types of questions have been used in other studies [21,22] . A sun exposure index was defined using the following variables: (1) frequency of outdoor activity for more than 15 min: daily = 7, 4-6 times a week = 5, 2-3 times a week = 2.5, once a week = 1, less than once a week/never = 0 [20,23] ; (2) usual time of day of outdoor activities: between 7 and 11 a.m. = 1, between 11 a.m. and 3 p.m. = 2, between 3 and 5 p.m. = 1 [21] ; (3) type of clothing worn outdoors: long pants, long sleeves, closed shoes, socks and hat = 0 each, short sleeves, short pants or skirts and open shoes = 1 each, bathing suit = 2 [24][25][26] ; (4) frequency of sunscreen use: never = 3, less than 3 times per week = 2, 3-6 times per week = 1, daily = 0 [27] ; (5) level of sunscreen protection: no use = 3, SPF ! 15 = 2, SPF 15-30 = 1, SPF 1 30 = 0 [22,28] . ...
... 0.05) compared to being outdoors less frequently. Other authors, using a similar categorization of sun exposure, have found sun exposure levels to be significantly correlated with serum 25(OH)D levels in normal-weight older US women [20] , normal-weight older adults in the UK during the summer (r = 0.62, p ! 0.01), but not during winter (r = 0.23, p ! 0.01) [38] , normalweight Danish women (r = 0.24, p ! 0.001) [23] and older Spanish individuals (r = 0.377, p ! 0.05) [27] . Since most of these studies were performed in normal-weight individuals, further studies are needed to understand the mechanisms of vitamin D photosynthesis in overweight and obese individuals. ...
... However, there was no statistically significant difference in vitamin D levels between those with and without a diagnosis of DVT. Lindqvist, et al.[7], Tangpricha, et al.[25] and Brot, et al.[26] stated in their studies that high vitamin D levels can prevent thrombosis. The limited amount of data in our study and the fact that it was conducted in a specific region may be the reason why there was no statistically significant result between vitamin D and DVT ...
Article
Full-text available
Abstract Aim: This study was conducted to evaluate the effect of vitamin D in patients with Factor V Leiden mutation (FVL) in the development of Deep Vein Thrombosis (DVT). Material and Method: This prospective clinical study was conducted to evaluate vitamin D levels in 110 participants carrying FVL with or without DVT. Patients who did not agree to participate in the study and did not come for routine controls were excluded from the study. Results: The mean age of the participants was 50±14.69 years, 47.3% were female, and 70% were diagnosed with DVT. The vitamin D level of 14.56% of the participants in the study was below 20ng/ml. Conclusion: There was no statistically significant difference in vitamin D levels between participants with and without DVT (p>0.05).
... For the final analysis, the following exclusion criteria which we have summarized and expanded from Brot et al. [23], were considered: (1) confirmed osteoporotic fractures or metabolic bone diseases; (2) current estradiol therapy; prior estradiol therapy is not an exclusion criterion if >3 months have elapsed since the last dose; (3) treatment with corticosteroids in the previous 12 months; (4) treatment of hyperthyroidism or hypothyroidism in the previous 12 months; (5) any new or unregulated chronic disease (e.g., unregulated diabetes); (6) malignant diseases at any time in life; (7) hysterectomy is not an exclusion criterion; (8) health conditions associated with vitamin D deficiency: malabsorption, chronic inflammatory bowel disease, gastrointestinal resection, liver disease, acute gallbladder disease, chronic kidney disease grade 3 to 5; (9) institutionalization and poor physical mobility; (10) excessive vitamin D intake (total 25(OH)D > 250 nmol/L). ...
Article
Full-text available
The objective of our study was to evaluate vitamin D status and its predictors in Slovenian premenopausal and postmenopausal women. A cross-sectional study was carried out between 1 March 2021 and 31 May 2021. A total of 319 healthy women from the Central Slovenian region aged between 44 and 65 were recruited; 176 were included in the final analysis. The vitamin D status was determined by measuring the total 25-Hydroxycholecalciferol (25(OH)D) concentration, vitamin D binding protein (DBP), and albumin and calculating the bioavailable 25(OH)D and free 25(OH)D. For the calculation of bioavailable and free 25(OH)D, we developed a new online calculator. The Endocrine Society’s thresholds for vitamin D deficiency and insufficiency were used; 29.0% of premenopausal and 24.4% of postmenopausal subjects were found to be vitamin D deficient (total 25(OH)D < 50 nmol/L); 76.8% of the premenopausal and 61.7% of postmenopausal subjects were found to have insufficient levels (total 25(OH)D < 75 nmol/L). Premenopausal women had 11.8% lower total 25(OH)D, 32.2% lower bioavailable 25(OH)D, and 25.2% higher DBP than postmenopausal women. The most important predictors of vitamin D status were vitamin D supplementation and time spent in the sun. Contrary to similar studies, the vitamin D status in Slovenian postmenopausal women was significantly better than in premenopausal women. In postmenopausal women, the measurement of free or bioavailable 25(OH)D instead of the total 25(OH)D could be advantageous.
... Hal ini juga kemungkinan menyebabkan kadar vitamin D dalam darah perempuan lebih rendah jika dibandingkan laki-laki. Studi di Denmark juga mendukung bahwa perilaku menghindar matahari pada perempuan sehat di Denmark saat musim panas akan menyebabkan tubuh kekurangan vitamin D pada musim dingin (28). Sinar matahari sangat diperlukan untuk proses biosistesis vitamin D di kulit. ...
Article
Full-text available
Blood level 25(OH)D3 in obese peopleBackground: Currently, obesity is a world problem, even the World Health Organization (WHO) declared obesity to be a global epidemic and contributes 5% of global deaths in 2015. Recently, many studies have reported an association between vitamin D levels and the incidence of obesity, although the exact mechanism raises many questions. Objective: This study is to examine the correlation between levels of 25(OH)D3 and body mass index (BMI).Methods: The design of this research is an analytic survey with a case control approach. The population of this study was all students of the Faculty of Medicine, Malahayati University, Bandar Lampung. The number of samples in this study were 60 samples with details of 30 case samples (obesity) and 30 control samples (no obesity). The sampling technique used was purposive sampling. The data used are primary data from direct measurement results. The data were analyzed using the correlation test.Results: The results showed that only one sample had normal 25(OH)D3 levels, while most (more than 98%) had low and very low levels of 25(OH)D3. The correlation test showed that there was a significant relationship between 25(OH)D3 levels with BMI (p=0.008; r= -0.0338), gender (p=0.001; r= -0.457), and total cholesterol levels (p=0.009); r= -0,391).Conclusions: There is a relationship between levels of 25(OH)D3 with BMI, the lower the 25(OH)3 blood level, the higher the risk of increasing BMI. Further research is still needed to ensure that giving vitamin D to obese populations can reduce body weight or BMI.
... Moreover, 25(OH)D deficiency was observed with a higher rate in women (78.7%) than men (66.4%)(41). In some studies, it has been reported that serum 25(OH)D levels varies seasonally and reaches their highest levels in the summer months(43). ...
Article
Full-text available
OBJECTIVE: In our study, it was purposed to research the distribution of vitamin D according to age, sex, and seasons of the patients diagnosed with obesity, cancer, and chronic renal failure who applied to Inonu University Turgut Ozal Medical Center between 2018-2021. MATERIALS AND METHODS: In our descriptive study, vitamin D measurements from 01.01.2018-01.01.2021 users who visited Inonu University Turgut Ozal Medical Center and were diagnosed with obesity, cancer, and chronic renal failure were scanned in their files and assessed retrospectively. The patients were grouped according to their sex, age, and seasons in which the samples were taken. 25(OH)D levels were analyzed by LC-MS/MS method. The patients were classified as deficient, inadequate, and normal in terms of vitamin D level RESULTS: Vitamin D deficiency was monitored in 54.9% (n = 981) of 1787 cancer patients admitted to our hospital, 63.3% (n = 558) of 882 chronic renal failure patients, and 65.8% (n = 1903) of 2894 obese patients. CONCLUSION: Of the 5563 obesity, cancer, and chronic renal failure patients who applied to our hospital; vitamin D deficiency was found in 61.9% (n = 3442), vitamin D deficiency was found in 23.1% (n = 1284), while vitamin D level was found to be normal in only 15% (n = 837). In terms of vitamin D deficiency, the highest deficiency was seen in obese patients with a rate
... [21] Some studies have presented significant correlations between serum 25(OH) D and self-reported sun exposure. [22][23][24] Some investigators have reported a positive association between oral supplementation of Vitamin D and serum 25(OH) D level. [23,25,26] However, Marwaha et al. could not find any association with calcium or Vitamin D supplementation and serum 25(OH) D level in their study among adult healthy Indians. ...
Article
Background: Vitamin D deficiency is highly prevalent among the Indian population and it is found to be associated with many diseases among perimenopausal women in various hospital-based studies. Objectives: This study aimed to find out the Vitamin D status among perimenopausal women and to assess the association of selected factors with Vitamin D status among them. Methods: A cross-sectional study was conducted among 184 perimenopausal women in two districts of Kerala from July 2018 to February 2019. The data were collected and blood sample was taken for determining the 25(OH) D levels after obtaining informed written consent. Descriptive and inferential statistics were done using SPSS version 22. Results: Among the 184 women, 2 (1.1%) had sufficient, 18 (9.8%) had insufficient, and 164 (89.1%) had deficient 25(OH) D levels. The mean 25(OH) D levels among the population were 15.01 ± 4.32 ng/ml (95% confidence interval 14.38-15.63), much lower than the required level of 30 ng/ml. Vitamin D level was significantly higher among women who had exposure to sunlight, were on Vitamin D supplementation, and those who had skin diseases. 25(OH) D levels were higher among residents of Ernakulam district, older age group, low socioeconomic status, mixed-diet consumers, those who attained menopause, and those had calcium supplementation. The level was low among those who regularly use sunscreen topical applications and had other comorbidities such as hypothyroidism. However, none of these factors were significantly associated with 25(OH) D levels. Conclusion: The study showed that Vitamin D deficiency is highly prevalent among the study population.
Article
Low 25-hydroxyvitamin D3 (25(OH)D) among dark-pigmented persons has been observed. To elucidate the reason for this we examined sun behaviour, sun-exposed body area, solar UVR exposure and 25(OH)D levels in immigrants with dark pigmented skin and Danes with light pigmented skin. Clothing, sun behaviour, and diet were recorded daily during a Danish summer season (93 analysed days). Erythema-weighted UVR doses were measured by personal electronic UVR dosimeters (with erythema response, measurement every 5th second) and 25(OH)D was measured in 72 participants (33 dark-skinned and 39 light-skinned). The immigrants exposed 28% less skin area, received 70% less UVR dose, and had 71% less 25(OH)D increase during the summer. The UVR reactivity (Δ25(OH)D per joule accumulated UVR dose) was similar (P = 0.62) among the immigrants (0.53 nmol l-1 J-1) and the Danes (0.63 nmol l-1 J-1). In the groups combined, 25(OH)D levels after summer were mainly influenced by UVR dose to exposed skin (28.8%) and 25(OH)D start level (27.9%). Height and measured constitutive skin pigmentation were of minor influence: 3.5% and 3.2%, respectively. Sun exposure and clothing habits were the main reasons for lower 25(OH)D level after summer in the darker immigrants, as both groups had similar UVR reactivity.
Article
Full-text available
Vitamin D deficiency is a major risk factor for bone loss and fracture. Although hypovitaminosis D has been detected frequently in elderly and housebound people, the prevalence of vitamin D deficiency among patients hospitalized on a general medical service is unknown. We assessed vitamin D intake, ultraviolet-light exposure, and risk factors for hypovitaminosis D and measured serum 25-hydroxyvitamin D, parathyroid hormone, and ionized calcium in 290 consecutive patients on a general medical ward. A total of 164 patients (57 percent) were considered vitamin D-deficient (serum concentration of 25-hydroxyvitamin D, < or = 15 ng per milliliter), of whom 65 (22 percent) were considered severely vitamin D-deficient (serum concentration of 25-hydroxyvitamin D, <8 ng per milliliter). Serum 25-hydroxyvitamin D concentrations were related inversely to parathyroid hormone concentrations. Lower vitamin D intake, less exposure to ultraviolet light, anticonvulsant-drug therapy, renal dialysis, nephrotic syndrome, hypertension, diabetes mellitus, winter season, higher serum concentrations of parathyroid hormone and alkaline phosphatase, and lower serum concentrations of ionized calcium and albumin were significant univariate predictors of hypovitaminosis D. Sixty-nine percent of the patients who consumed less than the recommended daily allowance of vitamin D and 43 percent of the patients with vitamin D intakes above the recommended daily allowance were vitamin D-deficient. Inadequate vitamin D intake, winter season, and housebound status were independent predictors of hypovitaminosis D in a multivariate model. In a subgroup of 77 patients less than 65 years of age without known risk factors for hypovitaminosis D, the prevalence of vitamin D deficiency was 42 percent. Hypovitaminosis D is common in general medical inpatients, including those with vitamin D intakes exceeding the recommended daily allowance and those without apparent risk factors for vitamin D deficiency.
Article
In this study, the effect of dietary calcium and vitamin D on serum parathyroid hormone and vitamin D metabolites was measured in 376 free-living women aged 65-77 y. Mean calcium intake in both groups was close to the recommended dietary allowance of 800 mg/d. Mean vitamin D intake in the 245 women not taking vitamin D supplements was 3.53 microg/d (141 IU/d), which is below the recommended dietary allowance of 5 microg/d (200 IU/d). To test the hypothesis that vitamin D is more important than calcium in reducing serum parathyroid hormone, the source of dietary calcium intake was subdivided into milk, which is fortified with vitamin D, and nonmilk sources. The serum parathyroid hormone concentration was inversely correlated with calcium intake derived from milk (r = -0.20, P < 0.01) but not from nonmilk sources (r = -0.06). Furthermore, serum calcidiol correlated with milk calcium intake (r = 0.35, P < 0.001) but not with nonmilk calcium intake (r = 0.10). Multivariate analysis showed a significant effect of season on serum calcidiol but not on serum parathyroid hormone. Serum parathyroid hormone was inversely correlated with serum calcidiol (r = -0.33, P < 0.001) and the regression predicted that mean serum parathyroid hormone would be reduced in the elderly to concentrations considered normal in the young when serum calcidiol is 122 nmol/L (49 ng/mL); this would require a much higher recommended dietary allowance for vitamin D than 5 microg/d (200 IU/d).
Article
Serum levels of total alkaline phosphatase activity (S-T-AP), wheat germ lectin-precipitated alkaline phosphatase activity (S-L-AP), and bone Gla-protein immunoreactivity (S-BGP) were measured in 26 patients (23 females and 3 males) aged 35–73 years (mean 59 years) with primary hyperparathyroidism (n=7), hyperthyroidism (n=9), and hypothyroidism (n=10) in whom the bone mineralization rate (m) was determined by47Ca-kinetics (continuously expanding calcium pool model). A weak positive correlation (r=0.42,P<0.05) was found between S-T-AP and m, which in the range from 0–18 mmol Ca/day could be estimated with a standard error of 4.6 mmol/day. A closer correlation (r=0.65,P<0.001) was found between S-L-AP and m which was estimated with an error of 3.9 mmol Ca/day. The AP activity in the supernatant showed no significant correlation to m (r=0.11,P>0.50). The highest correlation coefficient (r=0.81,P<0.001) was found between S-BGP and m which could be predicted with an error of 3.4 mmol Ca/day. S-BGP showed a closer correlation to S-L-AP (r=0.71,P<0.001) than to S-T-AP (r=0.58,P<0.01). We concluded that S-L-AP predicts bone mineralization at organ level better than S-T-AP in selected metabolic bone disorders and that the supernatant activity shows no relation to bone turnover. We find the assay easy to handle and suitable for large-scale use in the diagnosis and monitoring of metabolic bone disease.
Article
A competitive protein-binding assay for 25-hydroxyvitamin D (25-OHD) based upon a specific binding protein in the cytosol from rachitic rat kidneys is described. A diethyl ether extraction followed by separation by freezing was used. The extracts were chromatographed on short silicic acid columns, which separated 25-hydroxycholecalciferol from cholecalciferol, 24,25-dihydroxycholecalciferol, and 1,25-dihydroxycholecalciferol. A small aliquot of the 25-OHD fraction was used in the assay and free and bound vitamin were separated by dextran coated charcoal. The lower detection limit was 0.8 ng/ml (2.0 nmol/l). The levels of 25-OHD were measured in 596 healthy subjects and a seasonal variation was demonstrated. This variation, however, was only found in those without regular vitamin D intake, whereas the level of 25-OHD remained constant throughout the year in subjects with regular vitamin D supplement. The levels of 25-OHD were lower in the elderly subjects compared to younger ones, but seasonal variation was observed in both groups. In the summer months there was a significant correlation between age and the 25-OHD level. The mean levels of 25-OHD in Denmark are within the range of means found in the United States and Sweden but are higher than those reported from England, Belgium and France. This indicates a relatively high vitamin D intake in the Danish population and a low risk of nutritional vitamin D deficiency.
Article
To compare vitamin D status between countries in young adults and in the elderly. Reports on vitamin D status (as assessed by serum 25-hydroxyvitamin D) from 1971 to 1990 were reviewed. Studies were grouped according to geographic regions: North America (including Canada and the United States); Scandinavia (including Denmark, Finland, Norway, and Sweden); and Central and Western Europe (including Belgium, France, Germany, Ireland, The Netherlands, Switzerland, and the United Kingdom). Vitamin D status varies with the season in young adults and in the elderly, and is lower during the winter in Europe than in both North America and Scandinavia. Oral vitamin D intake is lower in Europe than in both North America and Scandinavia. Hypovitaminosis D and related abnormalities in bone chemistry are most common in elderly residents in Europe but are reported in all elderly populations. The vitamin D status in young adults and the elderly varies widely with the country of residence. Adequate exposure to summer sunlight is the essential means to ample supply, but oral intake augmented by both fortification and supplementation is necessary to maintain baseline stores. All countries should adopt a fortification policy. It seems likely that the elderly would benefit additionally from a daily supplement of 10 micrograms of vitamin D.