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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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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
... In the studies in the literature; serum 25(OH) vitamin D level reaches the highest level in summer. [18][19] Individuals living at latitudes of 37° and above are at a higher risk of vitamin D deficiency during winter months due to reduced UVB radiation. Denmark, located at 56°00' north latitude, reports common vitamin D deficiency during the winterspring period. ...
... Denmark, located at 56°00' north latitude, reports common vitamin D deficiency during the winterspring period. 19 Similarly, our country, located at 39°57' North latitude, may also experience vitamin D deficiency during the winter-spring period. The study results indicate that vitamin D deficiency is more prevalent during the spring months. ...
... 16 Vitamin D deficiency is more prevalent in women and at younger ages in the adult population. 13,15, 19 Çidem et al. 20 found no significant gender difference in 25(OH)D levels. However, Hekimsoy et al. 15 reported that 25(OH)D deficiency was more common in women (78.7%) than in men (66.4%). ...
Article
Full-text available
Aims: Vitamin D deficiency is a prevalent health issue globally. Outpatient clinics frequently encounter complaints related to vitamin D deficiency in adults. This study aims to determine the prevalence of 25(OH) vitamin D deficiency in patients over 18 years old and to investigate potential differences in 25-OH D levels based on age, gender, and seasonal factors. Methods: This cross-sectional study included 12,740 patients (9,550 females, 3,190 males) with a mean age of 45 years (ranging from 18 to 99 years) attending the Orthopaedics and Traumatology outpatient clinic and Internal Medicine outpatient clinic. The serum 25(OH) Vit D was measured using the ELISA method. The patients were divided into three groups: 1) patients with vitamin D deficiency (<20 ng/ml), 2) patients with insufficient vitamin D levels (21-29 ng/ml), and 3) patients with normal vitamin D values (>30 ng/ml). Binary logistic regression analysis was used to analyse the risk factors for vitamin D deficiency. Results: The study found that 68.6% of the participants had a vitamin D deficiency, while 21.2% had a vitamin D insufficiency. Binary logistic regression analysis revealed that low levels of 25(OH) Vitamin D were associated with age, gender, and the spring season. Conclusion: This study suggests that patients with related complaints or findings at outpatient clinic visits should be evaluated for vitamin D deficiency or insufficiency. If diagnosed, dietary support and vitamin D supplementation may be appropriate for those in high-risk groups.
... По данным ряда авторов, сывороточная концентрация ПТГ среди пациентов с СШТ статистически значимо выше, чем у сопоставимой группы сравнения (43,96+-25,3 пг/мл против 32,06+-11,7 пг/мл соответственно) [20], что в целом может соответствовать частоте ВГПТ среди женщин в постменопаузе, имеющих дефицит витамина D [25]. ...
Article
Hyperparathyroidism is a syndrome characterized by an excessive secretion of parathyroid hormone. Etiologically, hyperparathyroidism is subdivided into primary hyperparathyroidism, which develops as a result of parathyroid adenoma, carcinoma or hyperplasia, and secondary hyperparathyroidism, which happens as a compensatory response to a hypocalcemia caused by condition outside the parathyroid glands. Turner syndrome may also be accompanied by mineral metabolism disorders of various etiology. An association of hyperparathyroidism and Turner syndrome is interesting because of multifactorial impact on bone mineral density, but only few cases of such coexistence have been previously described in the literature. This article describes two patients with Turner syndrome and hyperparathyroidism of different etiology. Hyperparathyroidism, normocalcemia, vitamin D deficiency, osteoporosis, parathyroid tumors were found in both cases. In one case a number of assays was performed to confirm the patient’s normocalcemic primary hyperparathyroidism, and surgery was performed to achieve remission. In the second case, treatment of vitamin D deficiency resulted in normalization of serum concentration of parathormone, after which the patient was prescribed antiresorptive therapy. The pathogenetic association between Turner syndrome and hyperparathyroidism requires further investigation. Comprehensive approach to the diagnosis and treatment of mineral metabolism disorders are essential for patients with coexistence of these two diseases.
... Females were significantly better for testing their status than males. Studies from Libya denote that females are more susceptible to conditions necessitating investigation than males as women are less exposed to sunlight [8,9]. In spite, various researches that have been published so far to understand the potential risk factors and impacts of vitamin D deficiency, still, there is a scarcity of information regarding values (levels) among different Libyan populations [2,10]. ...
Article
Full-text available
This study was conducted to investigate levels among the target population and its associated risk factors in Libya.A cross-sectional study was conducted to investigate level and its associated risk factors in Libya during 2022-2023. 192 serum samples were tested in private laboratories. A structured designated questionnaire was filled in containing all the relevant information. Descriptive analyses frequency and percent were measured for numerical data, number, and percent for qualitative data using SPSS version 22. The chi-square test and student t-test were used for the data analysis and to investigate the level of association among variables at the significance level of (p<0.05). The ratio of female to male included in this study was estimated to be (77.04%) and (22.96%) respectively. Our results reported mean average of level among male (15.59 mg/dl), while in female (11.45 mg/dl), the results reported sex based significant difference (p=.00009). The present study results reported an overall average (12.40 mg/dl) of level. Regarding the age categories, our results reported variable differences in the levels, however there is no statistically significant difference (p=0.894). The results showed that using supplements for hypovitaminosis did not significantly influence therapeutic outcomes. The mean average level among males was significantly higher than those in females; however, both levels in the two groups are in the deficiency category. Interestingly the group who received treatment of vitamin D, their level was lower than the group who did not receive treatment
... Females were significantly better for testing their status than males. Studies from Libya denote that females are more susceptible to conditions necessitating investigation than males as women are less exposed to sunlight [8,9]. In spite, various researches that have been published so far to understand the potential risk factors and impacts of vitamin D deficiency, still, there is a scarcity of information regarding values (levels) among different Libyan populations [2,10]. ...
Article
Full-text available
This study was conducted to investigate levels among the target population and its associated risk factors in Libya.A cross-sectional study was conducted to investigate level and its associated risk factors in Libya during 2022-2023. 192 serum samples were tested in private laboratories. A structured designated questionnaire was filled in containing all the relevant information. Descriptive analyses frequency and percent were measured for numerical data, number, and percent for qualitative data using SPSS version 22. The chi-square test and student t-test were used for the data analysis and to investigate the level of association among variables at the significance level of (p<0.05). The ratio of female to male included in this study was estimated to be (77.04%) and (22.96%) respectively. Our results reported mean average of level among male (15.59 mg/dl), while in female (11.45 mg/dl), the results reported sex based significant difference (p=.00009). The present study results reported an overall average (12.40 mg/dl) of level. Regarding the age categories, our results reported variable differences in the levels, however there is no statistically significant difference (p=0.894). The results showed that using supplements for hypovitaminosis did not significantly influence therapeutic outcomes. The mean average level among males was significantly higher than those in females; however, both levels in the two groups are in the deficiency category. Interestingly the group who received treatment of vitamin D, their level was lower than the group who did not receive treatment.
... Seasonal variation in maternal serum vitamin D levels is among the major causes of the observed relationship between birth season and biological features of man, including BMD and BMC, indicated by most researchers. In European populations, especially those inhabiting the Northern part of the continent, vitamin D synthesis is limited to 5-6 months during the year (Brot et al. 2001). This limitation, while determining the maternal vitamin D level, may significantly control vitamin D levels in child's body, depending on the season of the year, during which prenatal development took place (characterised -at a given altitude -by specific conditions of exposure to sunlight, air temperature, the availability of fresh vegetable nutrition and the incidence of infections). ...
Article
Full-text available
In European populations, the birth season significantly correlates with many biological features. It is thus possible that the observed clinical effects of bone metabolism disorders are a partial consequence of bone mineral density (BMD), modified by the season of prenatal development (the birth season). The aim of this study was to evaluate the relationship between the birth season and BMD among Polish women in perimenopausal age. A total of 653 Polish women aged 50.0–59.9 years were included in the study. BMDs of lumbar vertebrae were measured by dual-energy x-ray absorptiometry. Statistical analyses were based on measured lumbar BMD values, age, and body mass index (BMI). The analysis of variance (ANOVA) was applied to evaluate the season-related differentiation of mineral density of lumbar vertebrae. BMDs of lumbar vertebrae negatively correlated with age and positively with BMI. We regressed BMD on age and BMI and used the residuals as a measure of age- and BMI-independent lumbar BMD values. The ANOVA results showed that women born in summer had significantly lower BMD of the L1 vertebra compared to those born in autumn, regardless of age and BMI. The results of our study indicate the need to extend the group of risk factors for osteoporosis in Central Europeans with the season of woman’s birth.
... Only relatively low levels of solar UV radiation reach the earth's surface in the winter, contributing to this seasonality [15]. Indeed, vitamin D levels tend to be lowest in the winter and highest in the summer in mid-and high-latitude regions such as China, Germany, Poland, and other Northern European nations [16][17][18][19][20][21][22]. Tis seasonal shift is also evident in Australia and other lowlatitude areas [23], indicating that season rather than latitude is the primary driver of this variation [24]. ...
Article
Full-text available
Background and aims: Previous studies have reported a correlation between vitamin D levels and seasonality in healthy populations. However, there are few studies on the seasonal variation in vitamin D levels and its relationship with glycosylated hemoglobin (HbA1c) in patients with type 2 diabetes mellitus (T2DM). The objective of this study was to investigate seasonal changes in serum 25-hydroxyvitamin D [25(OH)D] levels and the associations between these vitamin D concentrations and HbA1c levels in T2DM patients in Hebei, China. Methods: A cross-sectional study of 1,074 individuals with T2DM was conducted from May 2018 to September 2021. Levels of 25(OH)D in these patients were assessed based on both sex and season, and relevant clinical or laboratory variables that could impact vitamin D status were also considered. Results: In the T2DM patient cohort, the mean blood 25(OH)D levels were 17.05 ng/mL. A total of 698 patients (65.0%) had insufficient serum 25(OH)D levels. The vitamin D deficiency rates were significantly higher in the winter and spring compared to the autumn (P < 0.05), indicating that seasonal fluctuations can have a significant impact on 25(OH)D levels. The levels of vitamin D inadequacy were highest in the winter (74%), and females were more likely than males to be deficient (73.4% vs. 59.5%, P < 0.001). In comparison to the winter and spring, both males and females showed higher 25(OH)D levels in the summer (P < 0.001). HbA1c levels were 8.9% higher in those with vitamin D deficiencies than in nondeficient patients (P < 0.001). HbA1c and vitamin D levels were negatively correlated (r = -0.119, P < 0.001). Conclusion: Vitamin D deficiencies are particularly prevalent among T2DM patients in Hebei, China, with exceptionally high rates in the winter and spring. Female T2DM patients were at an elevated risk of vitamin D deficiency, and vitamin D levels were negatively correlated with HbA1c.
Article
Full-text available
Introduction Inadequate vitamin D status is a worldwide public health issue. In humans, vitamin D status is affected by diet, and even more by exposure to ultraviolet B (UVB) light and consequential endogenous synthesis. Various personal and environmental factors influence endogenous synthesis. Factors affecting vitamin D status were investigated in a prospective longitudinal cohort study with a summer and winter observation period. Methods The final sample included 292 adults, of those 111 (38%) males and 181 (62%) females, with a mean age of 38.2 (±11.8) years from Slovenia who were not supplementing vitamin D. Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured in both periods; vitamin D intake, self-reported body mass index (BMI), and protective behaviors against sun were also recorded. Other measured parameters included measurements of constitutive skin color using the objective individual typology angle (ITA), and difference in the melanin index (ΔMI) for assessment of objective sun exposure. Results In winter a high prevalence (63.4%) of insufficient vitamin D status (< 50 nmoL/L) was observed with higher odds ratios (OR) for insufficiency in those with a higher BMI and light ITA. During summer, insufficiency prevalence was low (5.5%), but half of the participants (50.0%) had suboptimal 25(OH)D concentration (< 75 nmol/L). In summer OR for suboptimal status were higher in those with obesity, lower ΔMI, light ITA, low vitamin D intake, and protective clothing behaviors. Conclusion Using a series of measures, we showed that vitamin D status is hugely affected by several personal factors such as BMI, ITA, vitamin D intake, ΔMI, and protective behavior against the sun. This conclusion questions the usefulness of generalized population-level recommendations since personal factors are a major predictor of vitamin D status.
Article
Este trabalho objetivou mensurar o impacto da luz solar como fator protetor para morte pela COVID-19 nos estados brasileiros, uma vez que a exposição ao sol é uma das fontes mais utilizadas para absorção de vitamina D e o aumento dos seus níveis no organismo humano pode combater diversas patologias. Para isso, controlou-se os efeitos das características climáticas dos estados, das medidas de distanciamento social impostas compulsoriamente pelos governos estaduais através de decretos e da adesão da população ao isolamento social medido pelo índice de isolamento social. Além disso, controlou-se os efeitos que as taxas referentes à COVID-19 sofrem no tempo e no espaço, fazendo uso de modelos espaciais dinâmicos para dados em painel. Os resultados mostraram que as taxas de morte pela COVID-19 no período corrente apresentam relação positiva e significante tanto das taxas ocorridas no período anterior como daquelas ocorridas nos estados vizinhos no período corrente e na véspera ao fazer uso das variáveis defasadas no tempo e no espaço. As variáveis climáticas também se mostraram preditoras das taxas de mortes COVID-19, indicando que estados com maior número de horas efetivas de luz do sol, maior temperatura e maior humidade relativa, têm uma diminuição nas suas taxas de morte pela COVID-19.
Article
To explore the joint association of time spent in outdoor light and genetic susceptibility with the risk of type 2 diabetes (T2D). A total of 395,809 individuals of European ancestry with diabetes-free at baseline in the UK Biobank were included. Time spent in outdoor light on a typical day in summer or winter was obtained from the questionnaire. T2D genetic risk was quantified via the polygenic risk score (PRS) and divided into three levels based on tertiles (lower, intermediate, and higher). T2D cases were ascertained according to the hospital records of diagnoses. After the median follow-up of 12.55 years, the association of outdoor light time and T2D risk demonstrated a nonlinear (J-shaped) trend. Compared to individuals with an average of 1.5-2.5 h/day of outdoor light, individuals who spent <1.5 h/day or > 2.5 h/day in outdoor light both had an elevated risk of T2D, and the risk of T2D related to <1.5 h/day outdoor light time was much higher (hazard ratio [HR] = 1.10, 95 % confidence interval [CI]: 1.06 to 1.15). After combining with PRS, in comparison with the lower PRS - average 1.5-2.5 h/day outdoor light group (reference), the higher PRS - < 1.5 h/day outdoor light group had the highest T2D risk (HR = 2.74, 95 % CI: 2.55 to 2.94), the higher PRS - > 2.5 h/day outdoor light group also had a higher risk of T2D (HR = 2.58, 95 % CI: 2.43 to 2.74). The interaction between average outdoor light time and genetic susceptibility for T2D was statistically significant (Paverage for interaction <0.001). We found that optimal outdoor light time may modify the genetic risk for T2D. This suggests the T2D risk related to genetic factors could be prevented by spending optimal outdoor light time.
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
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.