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R E S E A R C H A R T I C L E Open Access
Vitamin D deficiency in northern Taiwan: a
community-based cohort study
Ming-Jse Lee
1
, Heng-Jung Hsu
1,2,3
, I-Wen Wu
1,2
, Chiao-Yin Sun
1,2
, Ming-Kuo Ting
4
and Chin-Chan Lee
1,2*
Abstract
Background: Vitamin D deficiency has become an important public health problem, however few studies have
been conducted in subtropical countries, and the predictors of vitamin D deficiency in people with healthy renal
function are unclear. The objective of this study was to evaluate the prevalence and factors associated with vitamin
D deficiency in northern Taiwan.
Methods: The cross-sectional study was performed between August 2013 and August 2017, and included 3954
participants without chronic kidney disease (CKD) aged ≥30 years in northern Taiwan. Serum 25-hydroxyvitamin D
[25(OH)-D] levels, biochemistry, sociodemographic variables (age, sex, education, occupation) and lifestyle habits
(tea, coffee consumption and physical activities) were recorded. Associations between vitamin D status and these
variables were examined using a regression model. The definition of deficiency was defined as a serum 25(OH)-D
level < 20 ng/mL (50 nmol/L).
Results: The mean 25(OH)-D concentration was 28.9 ng/mL, and 22.4% of the study population had vitamin D
deficiency. There was a significantly higher vitamin D deficiency ratio in the women compared to the men
(22.9% vs 9.9%, p< 0.001). Vitamin D deficiency was most prevalent (38.4%) in those aged 30–39 years. Those with a
graduate degree had the highest rate of vitamin D deficiency (31.5%). The predictors of vitamin D deficiency
included female sex, young age, high education level, living in an urban area and physical inactivity. Tea
consumption was negatively associated with vitamin D deficiency.
Conclusions: Vitamin D deficiency is prevalent in subtropical areas such as northern Taiwan in healthy individuals
without CKD.
Keywords: Vitamin D deficiency, Prevalence, Risk factor, Taiwan
Background
The important role of vitamin D, a fat-soluble vitamin
responsible for calcium and phosphate resorption, in
bone health and mineralization is well known [1,2].
Vitamin D deficiency may cause secondary hyperpara-
thyroidism, rickets, osteomalacia, osteoporosis, and even
fragility fractures [3]. In the past decade, vitamin D has
also been shown to be involved in a wide variety of
extra-skeletal effects, and its deficiency has been associ-
ated with several health conditions including muscle
weakness [4], diabetes mellitus [5], chronic kidney
disease [6], cancer [7,8], cardiovascular disease [4], in-
fection, and autoimmune disease [9].
Vitamin D can be obtained from sun light or natural
food. However, natural food sources of vitamin D are
limited and mainly come from animal food in the form
of vitamin D3 only [10]. Thus, without artificial supple-
ments or vitamin-fortified food, the major source of
vitamin D comes from the action of ultraviolet-B light
upon the 7-dehydrocholesterol of the skin. Several
factors may influence the production of vitamin D in the
skin, including aging, latitude, skin pigmentation, season,
use of sun screen, outdoor activities and air pollution
[11,12].
Vitamin D deficiency has been reported to be more
common than previously thought, and it has become a
public health issue in modern societies [13,14]. Many
© The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
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reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
* Correspondence: leefang@adm.cgmh.org.tw
1
Division of Nephrology, Chang Gung Memorial Hospital, 222 Mai-Chin Road,
Keelung 204, Taiwan
2
College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
Full list of author information is available at the end of the article
Lee et al. BMC Public Health (2019) 19:337
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population-based studies on vitamin D deficiency have
been conducted, however most have been performed in
temperate countries with few being conducted in sub-
tropical regions. Because the prevalence of vitamin D
deficiency varies significantly in different countries and
populations [15], investigating the prevalence and associ-
ated sociodemographic factors of vitamin D deficiency
in subtropical areas is needed. In addition, to the best of
our knowledge, no previous study has focused on
healthy individuals without chronic kidney disease
(CKD). Since the level of 25(OH)-D declines with renal
function [16,17], CKD may influence the results related
to 25(OH)-D deficiency. In the present study, we evalu-
ated the 25(OH)-D concentrations, lifestyle habits, exer-
cise habits and past medical history, and also several
demographic and laboratory variables from a large sam-
ple of individuals without CKD in Keelung, a northern
city in Taiwan (latitude 25 N08’00″), to examine the
prevalence and sociodemographic factors independently
associated with 25 (OH) vitamin D [25(OH)-D] levels.
Methods
Study population and design
The study is based on data of a community health activ-
ity in four districts (Wanli, Ruifang, Gongliao and Anle)
in northern Taiwan from August 2013 to August 2017.
The community health activity included routine health
examinations (including blood tests and urine analysis)
and a questionnaire on health behavior for all residents
in the community. The aim of this program was to
detect and treat any health problems early and promote
health. Residents of the four districts who aged ≥30 years
and were not pregnant could join the health activity vol-
untarily after obtaining written informed consent. A
total of 4925 participants joined the healthy activity and
represent 4.2% of the population ages 30 and above in
the four districts. All of the participants were enrolled.
After excluding 971 participants with CKD, we obtained
a cohort of 3954 participants. The participants were di-
vided into two groups according to the level of plasma
25(OH)D; those with a level < 20 ng/mL (50 nmol/L)
were considered to be vitamin D deficient [18,19].
Demographic data (age, sex, residential district, occupa-
tion, and education level) and lifestyle habits (tea, coffee
consumption and exercise) were assessed from the ques-
tionnaires. Anthropometric and biochemistry measure-
ments were performed at entry to the study. Blood
samples were obtained after an overnight fast, and the
following parameters were determined: complete blood
cell count, liver and renal biochemistry parameters, lipid
profiles, fasting sugar, insulin, homeostatic model assess-
ment of insulin resistance (HOMA IR), intact parathy-
roid hormone (iPTH) and total 25(OH)-D levels. This
study was approved by the Ethics Committee of the
Institutional Review Board of Keelung Chang Gung Me-
morial Hospital.
Laboratory studies and definitions
We obtained complete laboratory profiles for individuals
in both groups. The laboratory parameters included the
plasma levels of blood urea nitrogen (BUN), creatinine,
hemoglobin, albumin, high sensitive C reactive protein
(hs-CRP), calcium, phosphate, alkaline phosphate, iPTH,
hemoglobin A1C and cholesterol. Plasma levels of BUN,
creatinine, hemoglobin, albumin, hs-CRP, calcium, phos-
phate, and cholesterol were assessed by spectrophoto-
metric analysis using a modified kinetic Jaffe reaction
with standardization of the creatinine calibration to an
isotope dilution mass spectrometry reference measure-
ment procedure. Plasma iPTH levels were measured
using a commercially available radioimmunoassay kit
(Scantibodies Laboratory; Santee, CA, USA). Serum level
of 25(OH)-D was measured using an electro-chemilumi-
nescence immunoassay (Cobas® Vitamin D3 assay, Roche
Diagnostics GmbH, Mannheim, Germany) with an inter-
assay coefficient of variation of 2.2–13.6%.
Chronic kidney disease was defined according to the
National Kidney Foundation K/DOQI classification for
CKD as persistent proteinuria or a decreased estimated
glomerular filtration rate (eGFR) of < 60 mL/min/1.73
m
2
, determined using the abbreviated Modification of
Diet in Renal Disease equation [20]. Proteinuria was
defined as a urine albumin-to-creatinine ratio > 30 mg/g
or urine protein-to-creatinine ratio > 150 mg/g. Vitamin
D deficiency was defined as a 25(OH)-D level <20 ng/
mL (50 nmol/L). Body mass index (BMI) was calculated
as the weight in kilograms divided by the square of the
height in meters. The participants were defined as being
tea and coffee drinkers if they had regularly drunk tea
and coffee for > 5 years. The physical activity level was
determined by weighting the reported hours per day of
any physical activity such as walking, dancing, garden-
ing, hiking, and swimming.
Statistical methods
Demographic and anthropometric statistics were ex
pressed as mean ± standard deviation as appropriate.
The Student’s t-test was used to compare the means of
continuous variables. Categorical data were tested using
the Chi-square test. The prevalence of vitamin D defi-
ciency was determined by sex, age group, education
level, occupation, residential district, tea and coffee
intake. Multiple logistic regression analysis was used to
identify the independent predictors of vitamin D defi-
ciency. Variables with a Pvalue < 0.05 and tea consump-
tion, which has been mentioned to have association with
vitamin D deficiency, were included in the multiple
logistic regression analysis. All reported Pvalues were
Lee et al. BMC Public Health (2019) 19:337 Page 2 of 8
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two-tailed, and were considered to be statistically signifi-
cant if they were < 0.05. Data were analyzed using SPSS
17.0 for Windows (SPSS Inc., Chicago, IL).
Results
A total of 3954 individuals without CKD aged ≥30 years
were included in this study. The mean age of the study
population was 55.48 ± 12.64 years. The mean 25(OH)-D
concentration of the study group was 28.94 ± 10.27 ng/
mL. Overall, 22.4% of the study population had a
25(OH)-D concentration < 20 ng/mL, and were defined
as having vitamin D deficiency. Significantly more
women had vitamin D deficiency than men (22.9% vs
9.9%, P< 0.001). The characteristics of the study group
are presented in Table 1. The mean age of the normal
vitamin D group was older than that of the vitamin D
deficiency group (56.98 ± 12.18 vs 48.81 ± 12.53 years; P
< 0.001). There were significantly more men in the nor-
mal vitamin D group than in the vitamin D deficiency
group (38.8% vs 19.1; P< 0.001). In addition, the normal
vitamin D group had a lower iPTH level (43.50 ± 19.10
vs 49.59 ± 22.69; P< 0.001) and higher hemoglobin level
(13.91 ± 1.48 vs 13.26 ± 1.61; P< 0.001) than the vitamin
D deficiency group. There were no significant differences
in lipid profile, insulin and HOMR IR between the two
groups.
The prevalence of vitamin D deficiency in various age
groups was illustrated in Fig. 1. The prevalence of vita-
min D deficiency was highest in the participants aged 30
to 39 years (38.4%), and then decreased gradually after
40 years of age reaching the lowest level between 70 to
79 years of age (7.2%). However, the prevalence increased
after 80 years of age (12.4%). The relationships between
vitamin D deficiency and education level are demon-
strated in Fig. 2. The ratios of vitamin D deficiency in-
creased with increasing education level, with the highest
rate observed in those with a graduate degree (31.5%).
The prevalence of vitamin D deficiency also varied by
occupation (Fig. 3), with the lowest prevalence in
farmers (5.4%) and the highest in service industry
workers (22.8%). Overall, the individuals working in agri-
culture, fishery, and manufacturing had a lower preva-
lence of vitamin D deficiency than those working in the
service industry, government employees, and home-
makers (11.4% vs 21.1%, P< 0.001). Figure 4shows the
rates of vitamin D deficiency in the four study districts
in northern Taiwan. Anle district had the highest per-
centage of vitamin D deficiency (21.7%), followed by
Table 1 Baseline characteristics according to the presence or absence of vitamin D deficiency
Normal Vitamin D Deficiency p-value
N 3230 724
Age (years) 56.98 ± 12.18 48.81 ± 12.53 < 0.001*
Male (%) 1253/3230 (38.8) 138/724 (19.1) < 0.001*
25(OH) D (ng/mL) 31.94 ± 8.77 15.49 ± 3.37 < 0.001*
Triglyceride (mg/dL) 118.50 ± 92.53 121.1 6 ± 110.50 0.500
HDL (mg/dL) 57.48 ± 14.98 56.67 ± 14.39 0.187
LDL (mg/dL) 126.90 ± 33.18 123.66 ± 31.94 0.099
Hemoglobin (g/dL) 13.91 ± 1.48 13.26 ± 1.61 < 0.001*
Alkaline P (U/L) 65.88 ± 19.56 63.38 ± 18.98 0.002*
Insulin (uU/mL) 7.91 ± 7.81 8.07 ± 7.25 0.630
HsCRP (mg/L) 2.15 ± 5.24 1.60 ± 2.43 < 0.001*
Creatinine (mg/dL) 0.74 ± 0.18 0.66 ± 0.15 < 0.001*
eGFR (ml/min/1.73 m2) 96.93 ± 21.52 107.93 ± 24.76 < 0.001*
Calcium (mg/dL) 9.36 ± 0.33 9.28 ± 0.33 < 0.001*
Phosphate (mg/dL) 3.81 ± 0.54 3.89 ± 0.51 < 0.001*
Albumin (g/dL) 4.71 ± 0.28 4.68 ± 0.27 0.011*
Hemoglobin A1C (%) 5.78 ± 0.68 5.73 ± 0.78 0.066
IPTH (pg/ml) 43.50 ± 19.10 49.59 ± 22.69 < 0.001*
HOMA IR (units) 2.10 ± 3.01 2.08 ± 2.52 0.915
BMI (kg/m2) 24.65 ± 3.72 23.96 ± 3.99 < 0.001*
Notes: Values are expresse d as mean ± SD or total number (percent)
*pvalue < 0.05
Statistical significance based on the Chi-square test for categorical variables or t-test for continuous variables
Abbreviation: HDL high density lipoprotein-cholesterol, LDL low density lipoprotein-cholesterol, Alkaline P alkaline phosphatase , HsCRP high sensitivity C-reactive
protein,eGFR estimate glomerular filtration rate, IPTH intact parathyroid hormone,HOMA-IR homeostasis model assessment of IR, BMI body mass index
Lee et al. BMC Public Health (2019) 19:337 Page 3 of 8
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Ruifang (19.9%), Gongliao (12.4%), and Wanli (11.1%)
districts.
With regards to the effect of daily diet and behavior
impacting the likelihood of vitamin D deficiency, regular
coffee drinking was associated with a higher prevalence
of vitamin D deficiency than non-consumption of coffee
(20.9% vs 13.9, P< 0.001). In contrast, there was no sig-
nificant difference in vitamin D deficiency between the
individuals who did and did not regularly drink tea
(19.0% vs 16.9%, P= 0.100) or take vitamin D supple-
ments (23.6% vs 18.1%, P= 0.101). In addition, increased
physical activity reduced the likelihood of developing
vitamin D deficiency.
In univariate analysis, many factors were associated
with vitamin D deficiency, so we performed multiple lo-
gistic regression analysis including all factors which
showed that younger age (30–40, 40–50, 50–60, 60–70
years), female sex, higher education level (graduate
school, university, senior high school), less physical ac-
tivity, and urban residential area (Anle district) were sig-
nificantly independently associated with vitamin D
deficiency, and that tea consumption was negatively in-
dependently associated with vitamin D deficiency
(Table 2).
Discussion
This study examined 25(OH)-D levels, the prevalence of
vitamin D deficiency and the associated predictors in
healthy adults with normal renal function in northern
Taiwan. To the best of our knowledge, this is the first
study to focus on a large sample of individuals without
CKD. Overall, we found that vitamin D deficiency was
common even in this population, and that the preva-
lence was particularly high in women, those with a
younger age, those who were better educated, and those
who lived in an urban area. In addition, tea consumption
seemed to be a protective factor against vitamin D
deficiency.
In the present study, the mean 25(OH)-D concentra-
tion of the study group was 28.94 ± 10.27 ng/mL and
22.4% had vitamin D deficiency (25(OH)-D concentra-
tion < 20 ng/mL). In the population-based National
Health and Nutrition Examination Survey conducted in
the United States from 2001 to 2006, 32% of the
Fig. 1 The prevalence of 25(OH) vitamin D deficiency in the study
population in different age groups by multivariate analysis (*P< 0.05)
Fig. 2 The prevalence of 25(OH) vitamin D deficiency in the study population in different education levels by multivariate analysis (*P< 0.05)
Lee et al. BMC Public Health (2019) 19:337 Page 4 of 8
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population had a serum 25(OH)-D concentration < 20
ng/mL [21]. In addition, the Korea National Health and
Nutrition Examination Survey conducted in 2008
reported prevalence rates of vitamin D deficiency (< 20
ng/mL) of 47.3% in males and 64.5% in females [22]. In
contrast, in a nationwide population-based study con-
ducted in Thailand, only 5.7% of the population had a
25(OH)-D level < 20 ng/mL [23]. The prevalence rate of
vitamin D deficiency in the current study was lower than
those in the studies from the United States and Korea
but higher than that in the study from Thailand, which
may reflect the effect of latitude. As sun exposure is an
important factor for vitamin D synthesis, people living at
a lower latitude may have more sun exposure and there-
fore a lower prevalence of vitamin D deficiency.
Many studies have demonstrated an increasing preva-
lence of vitamin D deficiency with age [24–26]. The
main reason may be that the elderly have decreased con-
centrations of 7-dehydrocholesterol, the precursor of
vitamin D3, and therefore have a decreased ability to
make vitamin D in the skin [27]. However, in the current
study, vitamin D deficiency was less prevalent with ad-
vancing age. Moreover, a young age was a risk factor for
vitamin D deficiency. Some studies have reported that
the elderly use more vitamin D supplements, and this
may explain the higher vitamin D value in the elderly
[28]. However, we found that the elderly subjects in this
study took less vitamin D supplements than the younger
subjects (30–39 years old: 34.6%, 40–49 years old: 34.8%,
50–59 years old: 32.1%, 60–69 years old: 27.5%, 70–79
years old: 16.8%, > 79 years old: 15.7%; P< 0.001). There-
fore, other factors must contribute to this phenomenon.
The amount of sun exposure is a possible factor. Young
people tend to spend more time indoors for study or
work in Taiwan. In contrast, the elderly may be able to
spend more time outdoors [22,23]. Moreover, young
people may use more sunblock because of cosmetic is-
sues, and therefore have less exposure to the sun [23].
We also investigated the effect of residential district
on vitamin D level, and found that Anle district, which
is an urban area, had a higher proportion of vitamin D
deficiency than Gongliao and Wanli districts, which are
rural areas. This finding is consistent with many other
Fig. 3 The prevalence of 25(OH) vitamin D deficiency in the study population in different occupations by multivariate analysis. Occupation
classification: (a) (Agriculture); (b) (Fishery); (c) (Manufacturing Industry); (d) (Government employee); (e) (Homemaker); (f) (Service
industry) (*P< 0.05)
Fig. 4 The prevalence of 25(OH) vitamin D deficiency in the study
population in different residential districts by multivariate
analysis (*P< 0.05)
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studies [23]. There are several reasons that may explain
the higher proportion of vitamin D deficiency in an
urban area. First, people in urban areas tend to spend
more time indoors due to their jobs and lifestyle. Sec-
ond, air pollution may be a risk factor for vitamin D de-
ficiency, and urban inhabitants are exposed to higher
levels of air pollution than rural inhabitants [11]. How-
ever, according to data from the Central Weather Bureau
of Taiwan, the concentrations of ozone and fine particu-
late matter (PM 2.5) are lower in urban areas than rural
areas. Therefore, lifestyle factors may be the reason why
the residents of the urban area had a higher percentage
of vitamin D deficiency than those in rural areas in the
present study.
Occupation was an important determinant of vitamin
D deficiency in this study, and those who worked in-
doors (including government employees, homemakers,
and service industry workers) had a higher risk of vita-
min D deficiency than those who worked outdoors (in-
cluding agriculture and fishery workers). Education
levels also had a significant impact on vitamin D defi-
ciency, and the subjects with a higher education level
were associated with a higher risk of vitamin D defi-
ciency. This finding is similar to the report by Daly et al.
[25]. However, in the multiple logistic regression analysis
including all factors, education level remained a risk fac-
tor of vitamin D deficiency whereas occupation did not.
This may reflect that the effect of education level was
Table 2 Multiple logistic regression analysis for associations with vitamin D deficiency
Univariate Odds ratio 95% CI Pvalue Multivariate Odds ratio 95% CI Pvalue
Male 0.372 0.305–0.453 < 0.001* 0.339 0.269–0.429 < 0.001*
Age (years)
30–40 Ref. Ref.
40–50 0.585 0.458–0.747 < 0.001* 0.605 0.460–0.795 < 0.001*
50–60 0.302 0.240–0.381 < 0.001* 0.396 0.301–0.520 < 0.001*
60–70 0.186 0.144–0.241 < 0.001* 0.309 0.223–0.430 < 0.001*
70–80 0.124 0.083–0.187 < 0.001* 0.292 0.176–0.484 < 0.001*
> 80 0.227 0.118–0.436 < 0.001* 0.662 0.299–1.468 0.308
Occupation
Agriculture Ref. Ref.
Fishery 1.019 0.266–3.905 0.978 1.460 0.358–5.951 0.597
Manufacturing industry 2.637 0.810–0.584 0.107 1.666 0.477–5.824 0.424
Government employee 4.023 1.223–13.226 0.022* 1.496 0.420–5.328 0.535
Homemaker 3.936 1.211–12.801 0.023* 1.801 0.516–6.289 0.357
Service industry 5.226 1.624–16.817 0.006* 2.058 0.594–7.132 0.255
Education level
Un-educated Ref. Ref.
Primary school 1.050 0.653–1.690 0.840 1.065 0.619–1.832 0.820
Junior high school 1.276 0.784–2.077 0.326 1.051 0.586–1.884 0.868
Senior high school 2.629 1.687–4.098 < 0.001* 1.944 1.111–3.400 0.020*
University 4.298 2.758–6.698 < 0.001* 2.706 1.510–4.848 0.001*
Graduate school 4.575 2.552–8.204 < 0.001* 2.915 1.390–6.115 0.005*
Residential district
Anle Ref. Ref.
Gongliao 0.509 0.386–0.670 < 0.001* 0.608 0.439–0.843 0.003*
Ruifang 0.894 0.719–1.113 0.317 1.122 0.869–1.450 0.377
Wanli 0.451 0.348–0.585 < 0.001* 0.500 0.373–0.670 < 0.001*
Coffee (yes) 1.635 1.368–1.955 < 0.001* 1.170 0.943–1.453 0.154
Tea (yes) 1.155 0.973–1.372 0.100 0.755 0.612–0.933 0.009*
Physical activity (hours/day) 0.499 0.410–0.607 < 0.001* 0.644 0.522–0.795 < 0.001*
*pvalue < 0.05.
Statistical significance based on the Chi-square test for categorical variable
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stronger than that of occupation. Education level would
influence the choice of occupation, lifestyle and behavior
factors. Those with a higher education level tend to be
younger, have indoor jobs, and be more concerned about
skin whitening and sun protection [29,30]. In contrast,
those with a lower education level tend to be older, have
outdoor jobs and not care about sun protection.
We also found a relationship between vitamin D defi-
ciency and tea and coffee consumption. To the best of our
knowledge, few studies have investigated this relationship
[31]. Although there was no significant difference in the
prevalence of vitamin D deficiency between those who did
and did not consume tea, tea consumption appeared to be
a protective factor against vitamin D deficiency after mul-
tiple regression analysis adjusting for confounding vari-
ables such as age, education and residential districts. It is
likely that these factors may confound the association
between vitamin D deficiency and tea consumption.
About the influence of age on the association of vitamin
D deficiency and tea consumption, the analysis showed
that the people who consumed tea were younger than
those who did not consume tea (53.05 ± 12.10 vs 59.73 ±
12.50 years; P< 0.001). The younger participants had a
higher prevalence of vitamin D deficiency, which may
have masked the benefit of tea consumption with regards
to 25(OH)-D level. In contrast, coffee consumption was
associated with a higher prevalence of vitamin D defi-
ciency compared to no coffee consumption. However,
coffee consumption was not an independent risk factor
for vitamin D deficiency after multiple logistic regression
analysis, which is consistent with the findings of
Al-Othman A et al. [31]. The mechanism underlying the
positive effect of tea consumption on the 25(OH)-D level
is not entirely clear, and further studies are needed to clar-
ify this relationship.
The strengths of this study are the large study
population and excluding patients with CKD. How-
ever, there are some limitations to the present study.
First, we did not obtain information about dietary in-
take of vitamin D, the amount of sun exposure and
other factors that may have influenced sun exposure,
such as clothing, the amount of time spent outdoors,
the use of sun-screen, and skin color. All of these
factors could affect the 25(OH)-D level. Second, some
of the data such as exercise and tea/coffee consump-
tion were obtained from questionnaires, which may
have introduced reporting or recall bias. Third, we
did not estimate the effect of the season or month of
blood sample collection on vitamin D deficiency.
Fourth,themethodweusedtomeasure25(OH)-D
values (radioimmunoassay) may have resulted in lower
values than the gold standard (liquid chromatography
tandem mass spectrometry), and may have overesti-
mated the prevalence of vitamin D deficiency [32].
Finally, our data were cross-sectional, and thus we
could not analyze longitudinal changes in vitamin D.
Conclusions
In conclusion, our data demonstrated that vitamin D
deficiency is prevalent in northern Taiwan, even in
healthy individuals without CKD. The prevalence was
particularly high in women, those who were younger,
better educated, and who lived in an urban area. Vita-
min D supplements are thus an important issue in
this group of people. Furthermore, we also found that
tea consumption had a protective effect on vitamin D
deficiency. Further studies are needed to confirm our
findings.
Acknowledgements
The authors wish to express their deepest gratitude to all the patients who
participated in this study.
Funding
This investigation was supported by a grant from Chang Gung Medical
Foundation Chang Gung Memorial Hospital, Keelung CMRPG2B0141–5 and
partially supported by CMRPG2A0433.
Availability of data and materials
The data that support the findings of this study are available from
Community Medicine Research Center, Chang Gung Memorial Hospital,
Keelung, Keelung, Taiwan but restrictions apply to the availability of these
data, which were used under license for the current study, and so are not
publicly available. Data are however available from the authors upon
reasonable request and with permission of Community Medicine Research
Center, Chang Gung Memorial Hospital, Keelung, Keelung, Taiwan.
Authors’contributions
MJL, IWW, CYS, MKT and CCL contributed to the planning of this paper. CCL
and MJL performed the study and conducted the analysis. MJL and HJH
drafted the manuscript. MJL, HJH, IWW, CYS, MKT and HJH contributed to
revisions, read and approved the final manuscript.
Ethics approval and consent to participate
This study was approved by the Institutional Review Board (IRB) of the
Chang Gung Memorial Hospital (IRB No:100-2248A3). All participants agreed
to the study conditions and provided written informed consent before the
enrollment in this study.
Consent for publication
Not applicable
Competing interests
The authors declare that they have no competing interests.
Publisher’sNote
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Author details
1
Division of Nephrology, Chang Gung Memorial Hospital, 222 Mai-Chin Road,
Keelung 204, Taiwan.
2
College of Medicine, Chang Gung University,
Tao-Yuan, Taiwan.
3
The Graduate Institute of Clinical Medical Sciences, Chang
Gung University Medical College, School of Medicine, Taoyuan, Taiwan.
4
Division of Endocrinology, Chang Gung Memorial Hospital, Keelung, Taiwan.
Lee et al. BMC Public Health (2019) 19:337 Page 7 of 8
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Received: 21 September 2018 Accepted: 14 March 2019
References
1. Johnson JA, Kumar R. Vitamin D and renal calcium transport. Curr Opin
Nephrol Hypertens. 1994;3(4):424–9.
2. Holick MF. Resurrection of vitamin D deficiency and rickets. J Clin Invest.
2006;116(8):2062–72.
3. Bell TD, Demay MB, Burnett-Bowie SA: The biology and pathology of vitamin D
control in bone. J Cell Biochem 2010, 111(1):7–13.
4. Gerdhem P, Ringsberg KA, Obrant KJ, Akesson K. Association between 25-
hydroxy vitamin D levels, physical activity, muscle strength and fractures in
the prospective population-based OPRA study of elderly women.
Osteoporos Int. 2005;16(11):1425–31.
5. Gagnon C, Lu ZX, Magliano DJ, Dunstan DW, Shaw JE, Zimmet PZ, Sikaris K,
Grantham N, Ebeling PR, Daly RM. Serum 25-hydroxyvitamin D, calcium
intake, and risk of type 2 diabetes after 5 years: results from a national,
population-based prospective study (the Australian diabetes, obesity and
lifestyle study). Diabetes Care. 2011;34(5):1133–8.
6. Kandula P, Dobre M, Schold JD, Schreiber MJ Jr, Mehrotra R, Navaneethan SD.
Vitamin D supplementation in chronic kidney disease: a systematic review and
meta-analysis of observational studies and randomized controlled trials. Clin J
Am Soc Nephrol. 2011;6(1):50–62.
7. Feldman D, Krishnan AV, Swami S, Giovannucci E, Feldman BJ. The role of
vitamin D in reducing cancer risk and progression. Nat Rev Cancer. 2014;14(5):
342–57.
8. Chowdhury R, Kunutsor S, Vitezova A, Oliver-Williams C, Chowdhury S, Kiefte-de-
Jong JC, Khan H, Baena CP, Prabhakaran D, Hoshen MB, et al. Vitamin D and risk
of cause specific death: systematic review and meta-analysis of observational
cohort and randomised intervention studies. BMJ (Clin Res Ed). 2014;348:g1903.
9. Agmon-Levin N, Theodor E, Segal RM, Shoenfeld Y. Vitamin D in
systemic and organ-specific autoimmune diseases. Clin Rev Allergy
Immunol. 2013;45(2):256–66.
10. Holick MF. Vitamin D Deficiency. N Engl J Med. 2007;357(3):266–81.
11. Manicourt DH, De vogelaer JP. Urban tropospheric ozone increases the
prevalence of vitamin D deficiency among Belgian postmenopausal
women with outdoor activities during summer. J Clin Endo crinol
Metab. 2008;93(10):3893–9.
12. Holick MF: Environmental factors that influence the cutaneous production of
vitamin D. Am J Clin Nutr 1995, 61(3 Suppl):638s–645s.
13. Holick MF. High prevalence of vitamin D inadequacy and implications for health.
Mayo Clin Proc. 2006;81(3):353–73.
14. Chapuy MC, Preziosi P, Maamer M, Arnaud S, Galan P, Hercberg S, Meunier PJ.
Prevalence of vitamin D insufficiency in an adult normal population. Osteoporos
Int. 1997;7(5):439–43.
15. Palacios C, Gonzalez L. Is vitamin D deficiency a major global public health
problem? J Steroid Biochem Mol Biol. 2014;144PA:138–45.
16. Mehrotra R, Kermah D, Budoff M, Salusky IB, Mao SS, Gao YL, Takasu J, Adler
S, Norris K. Hypovitaminosis D in chronic kidney disease. Clin J Am Soc
Nephrol. 2008;3(4):1144–51.
17. Restrepo Valencia CA, Aguirre Arango JV: Vitamin D (25(OH)D) in
patients with chronic kidney disease stages 2-5.Colomb Med (Cali,
Colombia) 2016, 47(3):160–166.
18. Forrest KY, Stuhldreher WL. Prevalence and correlates of vitamin D
deficiency in US adults. Nutri Res (N Y, NY). 2011;31(1):48–54.
19. Freishtat RJ, Iqbal SF, Pillai DK, Klein CJ, Ryan LM, Benton AS, Teach SJ. High
prevalence of vitamin D deficiency among inner-city African American youth
with asthma in Washington, DC. J Pediatr. 2010;156(6):948–52.
20. Initiative NKFKDOQ: NKF-K/DOQI clinical practice guidelines for chronic kidney
disease: evaluation, classification, and stratification–part 4: definition and
classification of stages of chronic kidney disease. Retrieved September 13, 2004.
In.; 2002.
21. Looker AC, Johnson CL, Lacher DA, Pfeiffer CM, Schleicher RL, Sempos CT.
Vitamin D status: United States. NCHS Data Brief. 2001-2006;2011(59):1–8.
22. Choi HS, Oh HJ, Choi H, Choi WH, Kim JG, Kim KM, Kim KJ, Rhee Y, Lim SK.
Vitamin D insufficiency in Korea--a greater threat to younger generation:
the Korea National Health and nutrition examination survey (KNHANES)
2008. J Clin Endocrinol Metab. 2011;96(3):643–51.
23. Chailurkit LO, Aekplakorn W, Ongphiphadhanakul B. Regional variation and
determinants of vitamin D status in sunshine-abundant Thailand. BMC
Public Health. 2011;11:853.
24. Jacques PF, Felson DT, Tucker KL, Mahnken B, Wilson PW, Rosenberg IH,
Rush D. Plasma 25-hydroxyvitamin D and its determinants in an elderly
population sample. Am J Clin Nutr. 1997;66(4):929–36.
25. Daly RM, Gagnon C, Lu ZX, Magliano DJ, Dunstan DW, Sikaris KA, Zimmet
PZ, Ebeling PR, Shaw JE. Prevalence of vitamin D deficiency and its
determinants in Australian adults aged 25 years and older: a national,
population-based study. Clin Endocrinol. 2012;77(1):26–35.
26. Rucker D, Allan JA, Fick GH, Hanley DA. Vitamin D insufficiency in a
population of healthy western Canadians. Can Med Assoc J. 2002;
166(12):1517–24.
27. Holick MF, Matsuoka LY, Wortsman J. Age, vitamin D, and solar ultraviolet.
Lancet (London, England). 1989;2(8671):1104–5.
28. Gill TK, Hill CL, Shanahan EM, Taylor AW, Appleton SL, Grant JF, Shi Z, Dal
Grande E, Price K, Adams RJ. Vitamin D levels in an Australian population.
BMC Public Health. 2014;14:1001.
29. Haluza D, Simic S, Moshammer H. Sun exposure prevalence and associated
skin health habits: results from the Austrian population-based UVSkinRisk
survey. Int J Environ Res Public Health. 2016;13(1):141.
30. Falk M, Anderson CD. Influence of age, gender, educational level and self-
estimation of skin type on sun exposure habits and readiness to increase
sun protection. Cancer Epidemiol. 2013;37(2):127–32.
31. Al-Othman A, Al-Musharaf S, Al-Daghri NM, Yakout S, Alkharfy KM, Al-Saleh
Y, Al-Attas OS, Alokail MS, Moharram O, Sabico S, et al. Tea and coffee
consumption in relation to vitamin D and calcium levels in Saudi
adolescents. Nutr J. 2012;11:56.
32. Roth HJ, Schmidt-Gayk H, Weber H, Niederau C. Accuracy and clinical
implications of seven 25-hydroxyvitamin D methods compared with liquid
chromatography-tandem mass spectrometry as a reference. Ann Clin
Biochem. 2008;45(Pt 2:153–9.
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