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Studies conducted among populations of tropical countries have reported high prevalences of vitamin D deficiency and insufficiency. Information resulting from meta-analyses on the spatial distribution of vitamin D deficiency and insufficiency in tropical countries is still rare. The aim of this review was investigated the prevalence of vitamin D deficiency and insufficiency among the Brazilian population. Observational studies were searched in eight electronically databases. Additionally, theses and dissertations and abstracts were screened. Details on study design, methods, population, mean and data on serum concentrations of vitamin D in different age groups in Brazil were extracted. Data were pooled using a random-effects model and choropleth maps were created based on the geopolitical regions of the country. 72 published paper met the inclusion criteria. The mean vitamin D concentration among the Brazilian population between 2000 and 2017 of 67.65 nmol/L (95% CI: 65.91, 69.38 nmol/L).The prevalences of vitamin D deficiency and insufficiency were 28.16% (95% CI: 23.90, 32.40) and 45.26% (95% CI: 35.82, 54.71), respectively, for the Brazilian population. The highest prevalence of deficiency were observed in the southern and southeastern regions and the highest occurrence of vitamin D insufficiency was among the populations of the southeastern and northeastern regions. Finally, there are high prevalence of inadequate vitamin D concentrations among the population, regardless of age group in Brazil. The development of vitamin D food fortification policies in needs to be cautious and carefully planned.
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Epidemiology of vitamin D insufciency and deciency in a population in a sunny
country: Geospatial meta-analysis in Brazil
Marcos Pereira-Santos
, Jos
e Yure Gomes dos Santos
, Gisele Queiroz Carvalho
, Djanilson Barbosa dos Santos
and Ana Marl
ucia Oliveira
Center of Biological and Health Sciences, Universidade Federal do Oeste da Bahia, Barreiras; Instituto de Sa
ude Coletiva, Universidade Federal da
Bahia, Salvador, Brazil;
Center of Humanities, Universidade Federal do Oeste da Bahia, Barreiras, Brazil;
Campus Avan¸cado de Governador Valadares,
Universidade Federal de Juiz de Fora, Minas Gerais, Brazil;
Center for Health Sciences, Universidade Federal do Rec^
oncavo da Bahia, Santo Ant^
onio de
Jesus, Brazil;
School of Nutrition, Universidade Federal da Bahia, Salvador, Brazil
Studies conducted among populations of tropical countries have reported high prevalences of vitamin D
deciency and insufciency. Information resulting from meta-analyses on the spatial distribution of vitamin
Ddeciency and insufciency in tropical countries is still rare. The aim of this review was investigated the
prevalence of vitamin D deciency and insufciency among the Brazilian population. Observational studies
were searched in eight electronically databases. Additionally, theses and dissertations and abstracts were
screened. Details on study design, methods, population, mean and data on serum concentrations of vitamin
D in different age groups in Brazil were extracted. Data were pooled using a random-effects model and
choropleth maps were created based on the geopolitical regions of the country. 72 published paper met the
inclusion criteria. The mean vitamin D concentration among the Brazilian population between 2000 and
2017 of 67.65 nmol/L (95% CI: 65.91, 69.38 nmol/L).The prevalences of vitamin D deciency and insufciency
were 28.16% (95% CI: 23.90, 32.40) and 45.26% (95% CI: 35.82, 54.71), respectively, for the Brazilian
population. The highest prevalence of deciency were observed in the southern and southeastern regions
and the highest occurrence of vitamin D insufciency was among the populations of the southeastern and
northeastern regions. Finally, there are high prevalence of inadequate vitamin D concentrations among the
population, regardless of age group in Brazil. The development of vitamin D food fortication policies in
needs to be cautious and carefully planned.
Vitamin D; vitamin D
deciency; systematic review;
Meta-analysis; Sunny country
Vitamin D is an essential fat-soluble vitamin for calcium
homeostasis and bone health (Palacios and Gonzalez, 2014).
An estimated 80% to 90% of vitamin D in the human body
originates from cutaneous synthesis by means of activation of
7-dehydrocholesterol through sunlight, while the remaining
20% to 10% are provided by either supplements or food
(Holick, 2004).
Low-latitude regions, such as Brazil, allow photosynthesis of
vitamin D at adequate concentrations during most seasons of
the year because of the availability of ultraviolet rays (UVB)
(Tsiaras and Weinstock, 2011) and the possibility that individ-
uals can be exposed to sunlight. However, paradoxically, studies
conducted among populations of tropical countries, such as
Brazil, have reported high prevalences of vitamin D deciency
and insufciency (Unger et al., 2010; Santos et al., 2012).
The nutritional state of vitamin D in the human body is
measured from the plasma levels of 25-hydroxyvitamin D (25
(OH)D). It was proposed from a review of the literature that 25
(OH)D vitamin concentrations below 50 nmol/l in adults
should be considered to represent vitamin deciency, while
those between 50 and 80 nmol/l 25(OH)D would indicate
insufciency (Holick, 2007). However, these cutoff points were
dened based on data from Western countries with high
proportions of elderly individuals in their populations (Hoteit
et al., 2014).
Vitamin D deciency and insufciency are associated with
several chronic endocrine-metabolic diseases (Holick and
Chen, 2008). In this regard, meta-analysis of data has shown
that vitamin D deciency were associated with increased risk of
cardiovascular diseases, diabetes, metabolic syndrome, obesity
and cancer (Luo et al., 2017; Qi et al., 2017; Pereira-Santos
et al., 2015; Zhang et al., 2017; Pludowski et al., 2013). The
clinical manifestations of vitamin D deciency include muscu-
loskeletal disorders, such as rickets and osteoporosis, and
increased occurrence of infections, while insufciency predis-
poses individuals to the risk of developing chronic diseases
with no clinical manifestations (Arabi et al., 2010).
CONTACT Marcos Pereira-Santos Rua Professor José Seabra de Lemos, 316, Recanto dos Pássaros, CEP: 47808-021 Barreiras,
Bahia, Brazil.
Color versions of one or more of the gures in the article can be found online at
Supplemental data for this article can be accessed on the publishers website.
Systematic Review Registration: PROSPERO number CRD42017076118.
© 2018 Taylor & Francis Group, LLC
The prevalence of vitamin D deciency worldwide remains
uncertain, since there is a lack of data from many countries
(Palacios and Gonzalez, 2014). In 2007, an estimated one bil-
lion people worldwide presented either vitamin D insufciency
or deciency (James, 2008). However, one decade later, the out-
come from this estimate remains unknown. Moreover, the
occurrence and distribution of vitamin D among South Ameri-
can populations is still poorly understood (van Schoor and
Lips, 2011) and research on the nutritional state of vitamin D
among the populations of sunny countries also remains scarce
(Santos et al., 2012).
In Brazil, studies conducted over the past few years have
revealed high prevalence of vitamin D deciency and insuf-
ciency among different age groups and in both sexes (Arabi
et al., 2010). In a healthy population in S~
ao Paulo, aged 18
90 years, vitamin D insufciency (vitamin D serum 25
<75 ml/L) was reported to affect 77.4% (Unger et al., 2010).
Slightly lower prevalence of insufciency (54.3%; 5075 nmol/
L) was identied among girls living in the municipality of Curi-
tiba (Santos et al., 2012).
Regarding vitamin D deciency (<50 nmol/l), high occur-
rences have been observed among different groups in Brazil:
36.3% among girls living in the municipality of Curitiba(Santos
et al., 2012); and 86% among elderly individuals in the southern
region of the country (Scalco et al., 2008). Therefore, in Brazil,
the results from studies on the nutritional state of vitamin D
among different age groups, whether healthy or not, support
the need to conduct a meta-analysis on vitamin D concentra-
tions in Brazil, a tropical country with high incidence of ultravi-
olet rays. Thus, the objective of the present study was to
estimate the prevalence and spatial distribution of vitamin D
deciency and insufciency in the Brazilian population.
The present systematic review and meta-analysis followed the
recommendations of the Meta-analysis Of Observational Stud-
ies in Epidemiology (MOOSE ) guidelines (Stroup et al., 2000).
In the supplementary le we have attached a MOOSE checklist.
The protocol for this systematic review was registered in the
PROSPERO registry prior to starting the literature search
(CRD 42017076118).
Search strategy and eligibility criteria
The PubMed, Bireme, Scopus, Web of Science, Science Direct,
SciELO and Lilacs databases were used to identify observational
studies that estimated the serum concentrations of vitamin D
among different age groups in Brazil. Published papers regis-
tered in these databases up to May 10, 2017 were identied
using the descriptors "vitamin D,ergocalciferols,cholecal-
ciferol,Braziland humans. Additionally, theses and disser-
tations were identied from the thesis database of Peri
Capes, and also abstracts from Brazilian conferences in the
elds of endocrinology and nutrition. At the end of the search,
we evaluated the reference lists of the articles on vitamin D, so
as to identify any studies that were not indexed in the databases
but might be pertinent for inclusion in this review (Table S1).
The search strategy was designed and conducted by an
epidemiologist with experience in development of systematic
review and meta-analysis (MPereira-Santos).
The inclusion criteria were that the articles, theses, disserta-
tions and conference papers should report on observational
studies from research that measured the serum concentrations
of vitamin D among non-hospitalized Brazilians, and should be
original. These studies could be published in any language.
Studies with an experimental design, opinionated reviews, edi-
torials, review articles and case reports were excluded. The
PICOS (population, intervention, comparison group, outcome,
and study design) criteria was used to guide the determination
of inclusion and exclusion criteria for this review (Table S2).
The published papers were managed using Mendeley and
the inclusion and exclusion criteria were applied by indepen-
dent reviewers (M Pereira-Santos and GQ Carvalho), who
selected the eligible articles. Articles were screened and selected
for full-text review if they met the selection criteria. At the end
of the review, disagreements about article inclusion were
resolved through reaching a consensus between the two
reviewers, who discussed eligibility and came to an agreement.
In the absence of a consensus, a third reviewer evaluated
whether the study in question was eligible (AM Oliveira).
The serum level of 25(OH)D was used as an indicator for
vitamin D status, because this metabolite reects the combined
effect of intake, skin synthesis, storage, blood transport protein
and catabolism (Holick, 2007). Moreover, hydroxylation of 25
(OH)D to 1.25(OH)2D3 (active vitamin D) occurs in several
tissues: the half-life of 25-OH-D is two to three weeks, while
the half-life of 1.25(OH)2D3 is approximately six hours (Mose-
kilde, 2005).
Data extraction
The articles thus selected were read in their entirety and infor-
mation regarding publication and design, sample, age of partic-
ipants, period when the study was conducted, technique for
assaying vitamin D, place of study and variables investigated
was recorded using a form designed for gathering this informa-
tion. The selected studies presented data from the outcomes of
the study, and no contact with authors was necessary.
Means, standard deviations and prevalence data regarding
vitamin D insufciency and deciency among the samples of
the studies selected were gathered. All 25(OH)D values in
nanograms per milliliter were converted to nanomoles per liter
by multiplying by 2.496, as necessary.
The 25(OH)D serum concentrations were dened as the
response variable in the present study. This measurement was
considered in its continuous form (mean vitamin D level) and
in categories, which were dened as either decient (<
50 nmol/L) or insufcient (50 nmol/L to 80 nmol/L). Normal
concentrations of vitamin D were not used in the present study.
Evaluation of the methodological quality of the studies
Two researchers (M Pereira-Santos, DB Santos) independently
scored the quality of the observation studies included in the
meta-analyses using an adapted version of the instrument pro-
posed by Loney et al. (1998) for critical evaluations on preva-
lence studies.
This instrument contains eight criteria for evaluating the
methodological quality of studies. However, one criterion
regarding impartial assessment made by trained evaluators was
excluded because it was not considered pertinent to the nature
of data collection, which in this case was blood sampling. Thus,
the following criteria were used: 1) probabilistic or census sam-
pling; 2) adequate source of sampling (ofcial census or school
census, among others); 3) previously calculated sample size; 4)
adequate method for measuring vitamin D; 5) adequate
response rate (>70.0%) and description of refusals; 6) presen-
tation of the condence intervals and analysis of the subgroups
of interest; and 7) well-described study subjects that are similar
to those of the research question (Loney et al., 1998).
For each criterion met, one point was attributed to the study
analyzed. High-quality studies were considered to be those that
reached 6 to 7 points; moderate quality between 4 and 5 points;
and low quality between 0 and 3 points (Loney et al., 1998).
The evaluation of methodological quality and risk of bias
was performed in relation to dissertations, theses and
articles. Conference abstracts were not assessed because the
information regarding the methodological quality of this
type of study was insufcient. Thus, abstracts were used to
obtain vitamin D mean, prevalence and insufciency data
from studies that were not published in the form of articles
or theses and dissertations. To do so, the Lattes curriculum
of the authors of the abstracts was accessed to certify
absence of publications regarding vitamin D.
Data analysis
The mean and prevalence of vitamin D deciency and insuf-
ciency were used as the meta-analysis summary measurements,
according to the geopolitical regions of Brazil: north, northeast,
center-west, southeast and south.
Mean vitamin D concentrations among the populations of
each region in Brazil and their respective condence intervals
(95% CI) were obtained following either the xed or the ran-
dom effects model, depending on the heterogeneity among the
studies. The heterogeneity and inconsistency of measurements
was identied through Cochrans Q test. If heterogeneity was
conrmed (p <0.05; I
>50%), the random effects model was
applied with inverse variance and weights according to the
results of individual studies (Higgins and Thompson, 2002).
Statistical analyses were performed using the Stata 12 software
(Stata Corp, College Station, TX, USA).
Geospatial analysis
Geospatial analysis was used in the meta-analysis to obtain the
mean values for the prevalences of vitamin D deciency and insuf-
ciency among the Brazilian population, which were calculated
according to the xed effects model. Choropleth maps were cre-
ated based on the regions of the country (north, northeast, center-
west, south and southeast), for the period of 2000 to 2017.
A quantication map was rst created using the method of
proportional symbols. To do so, occurrences of studies in each
of the catalogued municipalities were quantitatively represented
(Archela and Th
ery, 2008). This map also included the regional
classication of Brazil (north, northeast, center-west, southeast
and south) using the chorochromatic method, with colors as
the visual variable for establishing zones. Thus, each region of
the country received a specic color, which allowed them to be
Maps of vitamin D deciency, insufciency and mean concen-
tration were created using the mean vitamin D levels and preva-
lences of vitamin D deciency and insufciency from the meta-
analysis. Thus, the data from each region were georeferenced such
that higher prevalences of vitamin D deciency and insufciency
were represented on a scale of increasing color intensity.
The spatial representation of data was processed using the
ArcGISÒ10.4 software, to produce thematic maps. The carto-
graphic base used to produce the thematic maps of the present
study was obtained from the Brazilian Institute for Geography
and Statistics (IBGE, 2015).
Studies included
After screening (title and abstract), 108 studies were analyzed
regarding eligibility and 36 were excluded because they did not
meet the inclusion criteria. The reasons for excluding articles
were that they did not meet the criteria for the type of design
that had been previously dened; involved hospitalized partici-
pants; were not conducted within the study period dened; or
reported on the development of quantication methods for
vitamin D (Figure 1 and Table S2). In total, 72 studies were eli-
gible for inclusion in the systematic review and meta-analysis
(Figure 1, Table S3).
The studies thus analyzed (Table S4) involved a total of
340,476 Brazilians in different age groups. Most of them were
cross-sectional studies (93.0%) and analyzed adults and elderly
adults (Tables 1 and 2). Most investigations diagnosed the vita-
min D situation between 2006 and 2011 (37.5%) and between
2012 and 2017 (43.1%).
Quantication of serum 25(OH)D among the evaluated indi-
viduals was carried out using different techniques. Chemilumi-
nescence was the most commonly used technique (38.15%),
followed by radioimmunoassay (21.4%). Regarding methodo-
logical quality, 52.3% of the studies were classied as presenting
moderate and high levels of quality (33.5%) (Table 1).
Geospatial meta-analysis
Most of the studies were conducted in the southeastern region
(58.67%) and northeastern region (20.00%), while lower pro-
portions were conducted in the central-western and northern
regions of Brazil (Figure 2. Graph A). The mean vitamin D con-
centration for the Brazilian population between the years 2000
and 2017, from the meta-analysis, was 67.65 nmol/L (95% CI:
65.91, 69.38 nmol/L; Figure 2. Graph B). The highest level was
observed among the population in the northeastern region
(74.9 nmol/L).
The prevalence of vitamin D deciency was 28.16% (95% CI:
23.90,32.40) for the Brazilian population (Figure 4, Graph A).
The highest levels of deciency were observed in the southern
and southeastern regions (Figure 3- Graph A). In turn, the rate
of vitamin D insufciency (Figure 3- Graph B) was 45.26%
(95% CI: 35.82,54.71), and the highest occurrence was among
the populations of the southeastern and northeastern regions
(Figure 3- Graph B).
The situation of vitamin D deciency and insufciency did
not change according to the year in which the research was
conducted, nor was it inuenced by the age group involved in
the study (Table 2). However, the highest occurrence of vitamin
Ddeciency was reported among the elderly population
The present study was the rst meta-analysis to estimate the
prevalence of vitamin D deciency and insufciency for the
Figure 1. Study selection owchart.
Table 1. Main characteristics of selected studies on vitamin D concentration among the Brazilian population.
Variable N%
Year when study was published
20052009 13 18.3
20102014 23 26.7
20152017 36 55.0
Study design
Cross-sectional 67 93.0
Prospective cohort 5 7.0
Assay technique
CLIA chemiluminescence 27 38.5
HPLC high-sensitivity liquid chromatography 14 20.0
RIA radioimmunoassay 15 21.4
ECLIA chemiluminescence immunoassay 4 5.7
ELISA enzyme-linked immunosorbent assay 1 1.4
IRMA immunoradiometric assay 3 4.5
Not reported 6 8.5
Methodological quality- 63 studies
High quality - 6 to 7 points 21 33.5
Moderate quality - 4 to 5 points 33 52.3
Low quality - 0 to 3 points 9 14.2
Brazilian population according to the countrys geopolitical
regions. The mean serum concentration of vitamin D for the
population, which was obtained from observational studies,
was characterized as insufcient and did not seem to differ sig-
nicantly according to the age groups investigated. Thus,
despite the high solar incidence in Brazil, the prevalence of vita-
min D deciency and insufciency in this country was similar
to that of nations with reduced solar availability, regardless of
the age group investigated (Hilger et al., 2014).
The evidence available suggests that vitamin D deciency
can be considered to be a public health issue, since it affects all
phases of life in populations on different continents. In Euro-
pean countries, for example, the prevalence of vitamin D de-
ciency among the population was reported to be 40.4%
(Cashman et al., 2016). European data collected since 1913
(Mellaby, 1919) had already reported that vitamin D deciency
was more common among the population living in countries
with higher solar incidence, such as Italy, Spain and Greece,
than among the population of countries where solar exposure
was considered inadequate (Mellaby, 1919; Hilger et al., 2014).
This paradox can be explained by the concern for adopting
actions to prevent the risks of exposure to high levels of solar
incidence, independent of the concentration of solar irradiation
in these countries. This may lead to a decrease in individuals
contact with solar irradiation, thus raising the prevalence of
inadequate vitamin D levels in populations in tropical coun-
tries. This preventive action may also explain why there is a
high prevalence of vitamin D deciency in countries with low
solar incidence.
High prevalence of vitamin D insufciency and deciency
were identied in different age groups in the Brazilian
population. A similar result was observed in a meta-analysis
study that estimated occurrences of vitamin D deciency and
insufciency in different populations around the world (Hilger
et al., 2014).
Most of the studies included in the present meta-analysis
evaluated sample populations of elderly individuals or meno-
pausal women, which are populations that are vulnerable to
vitamin deciency and insufciency due to their reduced
capacity for cutaneous activation of 7-dehydrocholesterol, the
precursor for vitamin D. This condition may have contributed
towards increasing the prevalence of inadequate vitamin D
concentrations, but does not decrease the epidemiological
importance of the event. The studies selected also involved
Table 2. Serum vitamin D concentration and prevalence of deciency and insufciency of vitamin D, according to blood sampling and age group [95% condence
Variable Number of studies % Mean of vitamina D Vitamin D deciency Vitamin D insufciency
Year of data colleted
20002005 14 19.4 59.90 (49.47, 70.34) 39.25(20.41, 58.10) 38.24(27.03 ,49.44)
20062011 27 37.5 61.64(55.67, 67.617) 30.11 (18.18, 42.05) 55.54(45.48,65.60)
20122017 31 43.1 66.37(56.16, 76.59) 32.99 (24.28, 41.69) 46.65(40.06,53.25)
Pregnant women 5 6.6 65.0 (62.38, 67.70) 33.10 (8.84, 57.76) 48.91(8.81, 89.00)
Children 5 6.6 66.68 (35.51, 97.86) 22.95(10.00, 35.89) 44.04 (22.28,65.79)
Adolescents 11 15.7 72.44 (69.81, 75.08) 14.50 (1.80, 27.19) 57.93 (49.09, 66.76)
Adults 19 27.1 61.93 (51.18,72.68) 35.73(26.41, 45.04) 46.35 (35.78,56.92)
Elderly 20 28.5 52.859(45.01, 60.70) 41.53 (27.62, 55.44) 45.85 (36.21, 55.50)
Multiples groups 10 15.5 —— —
Figure 2. Occurrences of studies in each of the catalogued municipalities (A) and mean of vitamin D levels (B) among the Brazilian population.
adults and adolescents. Children and pregnant women were the
two least investigated groups.
Another possible cause of reduced synthesis of vitamin D
is intensive use of sunscreen, which is greatly encouraged by
dermatologists to prevent skin diseases. Use of sunscreen
has been correlated with vitamin D insufciency among the
Brazilian population. The physiological mechanism that
explains this process is the possible blocking of cutaneous
activation of provitamin D due to the sun protection factor.
Thus, sun protection factor (SPF) 8 can decrease vitamin D
photoproduction capacity by 90%, while SPF 30 decreases it
by 99% (Holick, 2007; Tsiaras and Weinstock, 2011). By
analogy, this mechanism can also explain how use of sun-
screen while performing daily activities, while at work, or
when practicing physical activities in enclosed environ-
ments, with low solar exposure, can decrease exposure to
UVB rays and thus how it may represent a risk factor for
vitamin D deciency and insufciency.
Moreover, during winter, people use more layers of clothes
and decrease their time spent outdoors. Air pollution and
working in closed environments, which limit cutaneous synthe-
sis of vitamin D, are other potential factor relating to vitamin D
insufciency and deciency (Holick, 2007; Tsiaras and Wein-
stock, 2011).
The factors associated with vitamin D deciency in the Bra-
zilian studies are similar to those reported in other Western
countries and include extremes of age, female sex, winter sea-
son, dark skin pigmentation, lack of sun exposure, a covered
clothing style and obesity (Arabi et al., 2010). Conversely,
younger age, practicing physical activities outdoors, the spring
and summer seasons, living by the sea in sunny locations and
lower latitudes are factors that seem to favor higher serum vita-
min D concentrations among the Brazilian population (Maeda
et al., 2014). However, Brazil is a continent-sized country, rang-
ing in latitude from 5Nto33
S. Thus, the intensity of UVB
light also varies signicantly across the different regions of
Figure 3. Spatial representation for the prevalences of vitamin D deciency ( A) and insufciency (B) among the Brazilian population.
Figure 4. Meta-analysis of prevalence of vitamin D deciency (A) and insufciency (B) among the Brazilian population.
Brazil, which can promote differences in occurrences of vitamin
D insufciency and deciency in the populations of the various
states of this country.
In lower-latitude regions, closer to the equator, cutaneous
synthesis may be high due to higher temperatures and intensity
of UVB rays (Palacios and Gonzalez., 2014). This explains the
lower prevalence of vitamin D deciency among the popula-
tions of the northern and northeastern regions of Brazil, where
the availability of sunshine and intensity of ultraviolet rays are
greater. Moreover, the habits and lifestyle of these populations
also favor solar exposure, especially in coastal cities, which
increases the possibility of vitamin D synthesis. Higher preva-
lences of deciency were observed in the southern and south-
eastern regions, where the incidence of ultraviolet rays is lower.
However, regarding vitamin D insufciency, the highest occur-
rence was observed among the populations of states in the
northeastern region. This indicates that availability of sunshine
and the presence of tropical coastal cities did not seem to inu-
ence the occurrence of this problem, even if the population was
protected from greater degrees of inadequacy.
The highest prevalences of vitamin D deciency were
reported from populations in the central-western, southeastern
and southern regions. Environmental factors may inuence the
vitamin D levels in the populations of these regions. High levels
of atmospheric pollution are among the environmental factors
that have been reported to occur in the states of these regions
(Vormittag et al., 2014). Air pollution due to particulate matter
), sulfur dioxide (SO
), ozone (O
), carbon monoxide
(CO) and nitrogen oxides (NOx), among others, block ultravio-
let rays and decrease the possibility that individuals will be able
to photosynthesize vitamin D (Feizabad et al., 2017).
In Brazil, vitamin D intake through dietary sources is low.
The small bioavailable quantities of this vitamin in food are
insufcient for the physiological needs of the human body
(Peters et al. 2009). Conversely, the availability of vitamin D in
foods in Brazil is mostly unknown. Not all food products
include information regarding vitamin D in the tables of per-
centage composition. This hinders studies evaluating vitamin
D intake and the repercussions of consuming dietary sources of
vitamin D on the serum concentrations of this compound in
any given population. Thus, quantication of vitamin D in Bra-
zilian foods and compilation of food composition tables should
be targeted in future studies.
In a prospective study on vitamin D levels in the adult popu-
lation of a Finnish cohort, it was reported that food fortica-
tion, especially of uid milk products, gave rise to adequate
vitamin D status when vitamin D intake was based on nutri-
tional recommendations [25(OH)D 50 nmol/L]. In such sit-
uations, supplementation would generally not be needed
ainen et al., 2017).
Vitamin D and 25(OH)D concentrations were observed to
increase after public policy actions aimed towards vitamin D
fortication in foods that are frequently consumed by the pop-
ulation (Black et al., 2012;J
ainen et al., 2017). Current
evidence does not support the recommendation of generalized
supplementation of vitamin D through medications, for popu-
lations (Peters et al., 2009). However, the results from the pres-
ent study and other studies support the recommendation that
policies towards fortication of foods with vitamin D for the
Brazilian population should be implemented, considering that
the main source of vitamin D in Brazil consists of occasional
exposure to sunlight.
The development of vitamin D food fortication policies in
Brazil needs to be cautious and carefully planned. The interests
of stakeholders within the pharmaceutical industry are pre-
dominantly focused towards implementation and commerciali-
zation of oral supplements and administration of mega-doses
of vitamin D among individuals in different age groups, who
may or may not be healthy, instead of promoting consumption
of foods that have been enriched with vitamin D.
Regarding the methodological quality of the studies ana-
lyzed, most presented moderate quality and moderate risk of
bias. The main problems of the studies related to absence of
sample calculations and use of non-probabilistic sampling.
Therefore, it is evident that epidemiological studies with repre-
sentative samples should be conducted on the repercussions of
vitamin D on the populations health, considering the scarcity
of prevalence assessments on 25(OH)D
levels among specic
population groups, such as pregnant women and children. The
cutoff points available for evaluating vitamin D concentrations
are another issue to be addressed, since these limits do not take
into account climatic particularities and the physiological needs
of each age group. The most common methods used to deter-
mine vitamin D concentrations were competitive assays based
on specic antibodies and non-radioactive markers. However,
high-performance liquid chromatography (HPLC), which
requires methodological certication through DEQAS (Inter-
national Vitamin D External Quality Assessment Scheme), was
also used. Prociency in determining vitamin D concentration
was not observed in the methodologies of the published papers
that were evaluated. Thus, there may be variations in the results
regarding vitamin D concentrations in studies that do not
adopt this parameter.
The present study provides contributions towards the eld
of public health through identifying the epidemiological situa-
tion of vitamin D deciency and insufciency among 340,476
Brazilians, including children, adolescents, pregnant women,
adults and the elderly. Moreover, these results relating to vita-
min D deciency and insufciency were spatially distributed
across the countrys geopolitical regions. However, most studies
included in this meta-analysis were prevalence studies, which
did not allow evaluation of causality relationships between vita-
min D deciency and insufciency and associated factors. In
addition, the northern and central-western regions were only
represented by a few studies on the vitamin D situation among
their populations, which hindered precise estimation of vitamin
D occurrences and deciencies.
The results from the present study indicate that there is a
need for intervention actions towards controlling vitamin D
deciency. Public policies towards vitamin D fortication in
foods consumed by the general public, except for specic
groups, should be developed. Supplementation can be reserved
for clinical practice, to assist individuals in situations of vulner-
ability to vitamin D deciency, such as elderly people, pregnant
women or people for whom supplementation would have a sig-
nicant impact, towards restoring and maintaining health. The
standardization of cutoff points for 25(OH)D should also be
further investigated, considering the physiological needs of
each group. According to the evidence of this study, we recom-
mend monitoring of vitamin D concentrations and comple-
mentation of daily needs through oral supplementation, when
necessary, among groups that are vulnerable to vitamin D de-
ciency (Maeda et al., 2014). Vitamin D deciency and insuf-
ciency should be considered to be a worldwide public health
issue, and Brazil forms part of this epidemiological scenario,
with high prevalences of decient and insufcient vitamin D
levels among the countrys population.
Disclosure of potential conicts of interest
No potential conicts of interest were disclosed.
M. Pereira-Santos was supported by the Brazilian National Research
Council (CNPq).
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... Insufficient vitamin D status in humans is becoming more common worldwide. 66 Studies on African, European, American, and Brazilian populations support a high prevalence of vitamin D deficiency, [67][68][69][70] and this is more common in urban than rural areas, and in newborns than their mothers. 67 Studies indicate that vitamin D prevalence is latituderelated given that serum vitamin D levels are higher in the northern regions of Brazil and the southern regions of China. ...
... 67 Studies indicate that vitamin D prevalence is latituderelated given that serum vitamin D levels are higher in the northern regions of Brazil and the southern regions of China. 70,71 In addition, serum 25(OH)D levels are not significantly related to gender and age worldwide. 72,73 Vitamin D insufficiency is very common among IBD patients, [8][9][10][11] with studies indicating that at least half of patients are vitamin D deficient. ...
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Zengrong Wu,1,2 Deliang Liu,1,2 Feihong Deng1,2 1Department of Gastroenterology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, People’s Republic of China; 2Research Center of Digestive Disease, Central South University, Changsha, Hunan, 410011, People’s Republic of ChinaCorrespondence: Feihong Deng, Department of Gastroenterology, The Second Xiangya Hospital, Central South University, Research Center of Digestive Disease, Central South University, Changsha, Hunan 410011, People’s Republic of China, Email Inflammatory bowel disease (IBD) is a nonspecific inflammatory disease that includes ulcerative colitis (UC) and Crohn’s disease (CD). The pathogenesis of IBD is not fully understood but is most reported associated with immune dysregulation, dysbacteriosis, genetic susceptibility, and environmental risk factors. Vitamin D is an essential nutrient for the human body, and it not only regulates bone metabolism but also the immune system, the intestinal microbiota and barrier. Vitamin D insufficiency is common in IBD patients, and the abnormal low levels of vitamin D are highly correlated with disease activity, treatment response, and risk of relapse of IBD. Accumulating evidence supports the protective role of vitamin D in IBD through regulating the adaptive and innate immunity, maintaining the intestinal barrier and balancing the gut microbiota. This report aims to provide a broad overview of the role vitamin D in the immune system, especially in the pathogenesis and treatment of IBD, and its possible role in predicting relapse.Keywords: vitamin D, immune system, inflammatory bowel disease, IBD treatment, relapse of IBD
... Latin America requires further investigation to optimally measure prevalence and take the necessary measures [46]. However, recent research shows that deficiency prevalence oscillates in the range of 28%-46% [47][48][49][50]. Interestingly, Pérez-Bravo et al. [51] worked on a sample of 1134 Chilean children aged 4-14 years and showed that 80.4% of this group had serum concentrations of vitamin D below 29.9 ng/ml; indicating insufficiency, according to the Endocrine Society [51]. ...
Vitamin D is considered an essential micronutrient for human health that is metabolized into a multifunctional secosteroid hormone. We can synthesize it in the skin through ultraviolet B (UVB) rays or acquire it from the diet. Its deficiency is a major global health problem that affects all ages and ethnic groups. Furthermore, dysregulation of vitamin D homeostasis has been associated with premature aging, driven by various cellular processes, including oxidative stress and cellular senescence. Various studies have shown that vitamin D can attenuate oxidative stress and delay cellular senescence, mainly by inducing the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and Klotho and improving mitochondrial homeostasis, proposing this vitamin as an excellent candidate for delaying aging. However, the mechanisms around these processes are not yet fully explored. Therefore, in this review, the effects of vitamin D on redox regulation and cellular senescence are discussed to propose new lines of research and clinical applications of vitamin D in the context of age-related diseases.
... Ling et al. [7] surveyed elderly people over 60 years old in different latitudes in our country, and showed that 92.28% of the elderly suffer from VD deficiency and insufficient; Xu's [8] findings suggest that 62.40% of young males and 52.39% of young females in East China had VD deficiency. VD is generally lacking in people all over the world, even in high sunshine areas such as Algeria, Libya, and Brazil [9][10][11]. ...
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Abstract Background Iron and vitamin D (VD) is essential to health. Previous studies have shown that iron homeostasis has a potential effect on VD metabolism, but the mechanism is not fully understood. Objectives To explore the relationship between VD metabolism and iron metabolism, as well as the regulatory mechanism of iron on VD metabolism. Methods 40 male rats were fed adaptively for 7 days and randomly divided into control (C, n = 6 normal diet) group and model (M, n = 24 iron deficient diet) by simple randomization, the latter was used to establish iron deficiency anemia (IDA) model. After 6 weeks of feeding, the M group was randomly divided into: iron deficiency group (DFe), low iron group (LFe), medium iron group (MFe) and high iron group (HFe) by block randomization. Different doses of iron dextran (based on iron content (100 g·bw·d)): 0, 1.1, 3.3 and 9.9 mg) were given respectively. After 4 weeks, the rats were anesthetized with 8% chloral hydrate, Blood (collected from the abdominal aorta), liver and kidney tissues were collected. The serum and tissues were separately packed and frozen at -80℃ for testing. Results The results showed that the levels of hemoglobin (Hb), red blood cell (RBC), serum iron (SI), liver iron, and kidney iron in DFe group were lower than those in the other four groups, while the levels of total iron-binding capacity (TIBC), transferrin (TF) and transferrin receptor (Tfr) in DFe group were higher than those in other groups; The serum levels of 25-(OH)D3 and 1,25-(OH)2D3 in DFe group were significantly lower than those in C group (P
... A Brazilian epidemiological study showed reduced levels of vitamin D in the southeast region of the country [50]. However, the Brazilian population of mixed ethnicity and the fluctuation of 25(OH)D 3 levels during the seasons of the year must be considered [51]. ...
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Objective: To evaluate the association of genetic polymorphisms of vitamin D transporter protein (DBPrs4588 and DBP-rs7041) and cytochrome P450-24A1 (CYP24A1-rs6013897) in patients with cirrhosis with or without hepatocellular carcinoma (HCC), including demographic/clinical/biochemical profiles. Methods: A total of 383 individuals were studied, considering the total group (TotalG) of patients with cirrhosis (TotalG: N = 158) with or without HCC, distributed into Group 1 (G1): cirrhosis and HCC; Group 2 (G2): isolated cirrhosis; and 225 individuals without hepatopathies (G3). Polymorphisms were analysed by real-time polymerase chain reaction. An alpha error of 5% was admitted. Results: CYP24A1-rs6013897 predominated the genotype with at least one polymorphic allele (_/T) in G1 (98.3%) versus G2 (88.8%; p = 0.0309). There was a moderate positive correlation between vitamin D and parathyroid hormone in patients (TotalG: R2 = 0.3273). Smoking, alcoholism and diabetes mellitus (DM) stood out as independent factors for cirrhosis, as well as for cirrhosis with HCC, except for smoking, adding, in this case, advanced age, male gender, polymorphic allele of CYP24A1-rs6013897, viral hepatitis and high levels of serum gamma-glutamyl transferase (GGT), alpha-fetoprotein (AFP) and creatinine. An increase in survival was observed in the presence of the polymorphic allele of DBP-rs7041 (p = 0.0282). Conclusion: CYP24A1-rs6013897 is associated with cirrhosis and HCC as a predictor, while DBP-rs4588 is associated with reduced vitamin D, and DBP-rs7041 provides increased survival, suggesting a protective characteristic. Advanced age, alcoholism, DM, viral hepatitis and high levels of GGT, AFP and creatinine are also confirmed as predictors of HCC and cirrhosis, while smoking, alcoholism and DM for isolated cirrhosis only.
Objective The main growth hormone action is to promote linear growth increasing protein synthesis stimulation and osteoblastic activity. Peak bone mass extends from adolescence to 30 years of age. Several factors may influence this acquisition and prevent fracture risk in adulthood, such as genetic potential, GH, ethnicity, and lifestyle factors. This study aims to compare bone mass and osteometabolic profile of white and Afro-descendant Brazilian adolescents in the transition phase, who were treated with human recombinant growth hormone in childhood. Methods The authors selected 38 adolescents from the Transition Outpatient Clinic of the University of São Paulo. Lumbar spine and total body bone mineral density (BMD) and bone mineral content (BMC), serum calcium, 25-OH-vitamin D and bone markers were analyzed at the rhGH withdrawal. Results The mean age was 16.8 ± 1.6 years. There were 21 Afro-descendant and 17 whites. Thirty-four percent of the sample presented vitamin D insufficiency, 66% inadequate calcium intake and 44.7% physical inactivity. The Afro-descendants showed a lower lumbar spine and total body Z scores than those of the whites (p = 0.04 and p = 0.03, respectively), as well as their mean body weight (p = 0.03). There were no differences in the remaining osteometabolic parameters. Conclusion As most adolescents had vitamin D insufficiency, low calcium intake, and physical inactivity, calcium, and cholecalciferol supplementation and lifestyle changes should be encouraged. The Brazilian Afro-descendant may be a vulnerable group for low bone mass, requiring special strategies to increase bone accrual and body weight. More studies are necessary to compare ethnic differences in this population.
Colorectal cancer (CRC) is the third leading cause of cancer-related mortality in the United States and the second cause worldwide. Its incidence rates have been decreasing in the overall population in the US in the past few decades, but with increasing rates in the population younger than 50 years old. Environmental factors are supposed to be involved in the development of the disease, with strong evidence favoring an influence of the diet and lifestyle. A diet high in red meat and calories, and low in fiber, fruits and vegetables increases the risk of CRC, as well as physical inactivity. The influence of low calcium intake and low levels of vitamin D on the risk of the disease and on the clinical outcomes of CRC patients has also been investigated. Hypovitaminosis D has been highly prevalent worldwide and associated with several chronic diseases, including malignancies. Vitamin D is a steroid hormone with the main function of regulating bone metabolism, but with many other physiological functions, such as anti-inflammatory, immunomodulatory, and antiangiogenic effects, potentially acting as a carcinogenesis inhibitor. In this review, we aim to describe the relation of vitamin D with malignant diseases, mainly CRC, as well as to highlight the results of the studies which addressed the potential role of vitamin D in the development and progression of the disease. In addition, we will present the results of the pivotal randomized clinical trials that evaluated the impact of vitamin D supplementation on the clinical outcomes of patients with CRC.
Nutrition is a key factor in the development of non-communicable chronic diseases (NCCDs), especially cardiovascular diseases (CVD) and their risk factors. The “double burden of malnutrition” (DBM) is the coexistence of undernutrition and overnutrition in the same population across the life-course. In Latin America, the transition from a predominantly underweight to an overweight and obese population has increased more rapidly than in other regions in the world. Undernutrition and the micronutrient deficiencies particularly iron, zinc, and vitamins A and D, present high heterogeneity in Latin American countries, and are currently considered important public health problems. In this region, NCCDs account for 50% of the disability-adjusted life-years, led by CVD. The most prevalent cardiovascular risk factors are overweight, obesity, hypertension, dyslipidemia and type 2 diabetes mellitus. Because of the cost of treatment and the potential years of life lost due to premature death, CVD is known to affect the poorest segments of the population, affecting communities, and governments. More than 80% of CVD deaths occur in low- and middle-income countries. The persistence of damage in some cells due to undernutrition may explain certain findings regarding the increase in NCCD. These aspects together with epigenetic changes have highlighted the importance of a lifelong approach to nutritional policy development. Reducing DBM requires major societal interventions in public health and nutrition to achieve holistic change that can be sustained over the long term and spread throughout the global food system. The implementation of effective state policies of double impact actions should influence both sides of the burden and be considered an urgent priority, considering country-specific inequalities and socio-demographic differences in the Latin American region, using diverse and multidisciplinary strategies.
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Vitamin D deficiency is associated with an increase in the occurrence of cardiometabolic events, but the evidence of this relationship in adolescence is still limited. Thus, we analyzed the association between vitamin D deficiency and cardiometabolic risk factors in adolescents. Observational studies were searching in PubMed/Medline, Embase, Scopus, Web of Science, Science Direct, Lilacs, and Google Scholar database. Random effects models were used to summarize standardized mean differences for as a summary measure. The certainty of the evidence was verified using the Cochrane recommendations. A total of 7537 studies were identified, of which 32 were included in the systematic review and 24 in the meta-analysis.Vitamin D deficiency was associated with increased systolic pressure (SMD = 0.22; 95%CI = 0.10; 0.34), diastolic pressure (SMD = 0.23; 95%CI = 0.10; 0.35), glycemia (SMD = 0.13; 95%CI = 0.05; 0.12), and insulin (SMD = 0.50; 95%CI = 0.15; 0.84), an increase in the HOMA index (SMD = 0.48; 95%CI = 0.36; 0.60), high triglyceride values (SMD = 0.30; 95%CI = 0.11; 0.49), and reduced HDL concentrations (SMD= -0.25; 95%CI = -0.46; -0.04). No statistically significant association was observed for glycated hemoglobin, LDL cholesterol, and total cholesterol. Most of the studies presented low and moderate risks of bias, respectively. The certainty of the evidence was very low for all the outcomes analyzed. Vitamin D deficiency was associated with increased exposure to the factors linked to the occurrence of cardiometabolic diseases in adolescents. Systematic Review Registration: PROSPERO (record number 42,018,086,298).
The risk for cardiovascular diseases (CVR) has been associated with oxidative DNA damage, but the genetic and environmental factors involved in the antioxidant and DNA repair system contributing to this damage are unknown. The aim was to evaluate the levels of oxidative DNA damage in CVR subjects and how it is related with some genetic and nutritional factors. The cross-sectional study evaluated 136 individuals of both sexes, aged 20-59 years, with at least one cardiovascular risk factor. The global risk score was used to classify individuals at low, intermediate and high cardiovascular risk. The dietary total antioxidant capacity (DTAC) was calculated using table with FRAP values. The oxidative DNA damage was verified by the comet assay. The variants null of Glutathione-S-transferases Mu1 and Theta 1(GSTM1 and GSTT1) and rs25487 of X-Ray Repair Cross Complementing Protein 1 (XRCC1) were analyzed by real-time PCR and PCR-RFLP, respectively. The oxidative DNA damage was higher in patients with intermediate/high CVR than in patients with low CVR (p=0.01). Individuals with GSTT1/GSTM1 null genotypes or arg/gln + gln/gln genotypes of the XRCC1 (rs25487) gene showed similar levels of oxidative DNA damage compared wild genotype. Multivariate regression analysis demonstrated that oxidative DNA damage in individuals with CVR depends on serum levels of vitamin A, selenium and DTAC independently of the other factors [F(6.110)=8.213; p<0.001; R2=0.330]. These findings suggest that nutritional factors such as DTAC, vitamin A and selenium may have a protective effect against oxidative DNA damage in these individuals.
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Background: Vitamin D deficiency is a common consequence of bariatric surgery (BS). However, few studies have evaluated influential factors and to date there are no studies investigating individual ultraviolet B (UVB) radiation levels in BS patients. This study aimed to evaluate vitamin D deficiency and its associated factors, including UVB radiation, in Roux-Y gastric bypass (RYGB) patients. Methods: This study included 104 adults (90.4% female) at least 5 years after RYGB. Patients underwent surgery in private hospitals (Private; n = 47) or in two public hospitals, one with ongoing outpatient care (Active; n = 17), and the other with discontinued service for BS (Discontinued; n = 40). 25-hydroxyvitamin D (25(OH)D) concentrations were analyzed by chemiluminescence, individual UVB radiation levels by dosimeter badges. Vitamin D intake, anthropometric, skin phototype, sociodemographic and lifestyle patterns were also assessed. Results: Mean age was 49.6 ± 9.1 years and post-operative period 8.7 ± 2.2 years. The prevalence of 25(OH)D deficiency and insufficiency was 25.0% and 51.9% respectively. 25(OH)D concentration differed among the hospitals (private = 26.2 ± 8.5; active = 28.7 ± 11.4; discontinued = 23.5 ± 6.5 ng/mL; p = 0.038). A total of 26.2% of the variance observed in 25(OH)D concentrations was explained by daily UVB radiation levels (β = 0.224; p = 0.032) and vitamin D intake (β = 0.431; p < 0.001), controlling for age and BMI. Conclusion: A quarter of the evaluated patients presented vitamin D deficiency, which was associated with the discontinuation of the health care, higher BMI, lower vitamin D intake, and lower individual UVB radiation levels.
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The association between air pollution and bone health was evaluated in adolescents in the city of Tehran. This study is essentially ecological. Vitamin D deficiency among adolescents has been reported at higher rates in polluted areas than in non-polluted areas. Additionally, residence in polluted areas is associated with lower levels of bone alkaline phosphatase. PurposeThe aim of this study was to evaluate the association between ambient air pollution and bone turnover in adolescents and to compare the prevalence of vitamin D deficiency between polluted and non-polluted areas of Tehran. Methods This cross-sectional population-based study was conducted on 325 middle- and high-school students (both girls and boys) in Tehran in the winter. During the study period, detailed daily data on air pollution were obtained from archived data collected by Tehran Air Quality Control Company (AQCC). Serum levels of calcium, phosphorus, parathyroid hormone (PTH), bone-specific alkaline phosphatase, 25(OH) vitamin D, osteocalcin, cross-linked C-telopeptide (CTX), total protein, albumin, and creatinine were obtained from the study group. ResultsVitamin D deficiency was more prevalent in polluted areas than in non-polluted areas. After adjustment for age and sex, residence in the polluted area showed a statistically significant positive association with vitamin D deficiency and a statistically significant negative association with bone turnover. Interestingly, high calcium intake (>5000 mg/week) protects against the effects of air pollution on bone turnover. Conclusions Air pollution is a chief factor determining the amount of solar UVB that reaches the earth’s surface. Thus, atmospheric pollution may play a significant independent role in the development of vitamin D deficiency.
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Objectives The study sought to determine the link between vitamin D concentrations and incident hypertension in prospective study and meta-analysis. Methods The study was embedded in the Kailuan Study, a population-based cohort of adults that contains underground miners. In 2012, we studied 2,456 men and women free of prevalent hypertension, age 21 to 67 at baseline. Serum 25-hydroxyvitamin D was measured from previously frozen baseline samples using ELISA (Enzyme-Linked ImmunoadSorbent Assay). We use the logistic regression analysis to estimate the odd radio (ORs) 95% confidence intervals (CIs) for 25-hydroxyvitamin D [25(OH)D] concentrations with incident hypertension. To help place our new data in context, we conducted a systemic review and meta-analysis of previous prospective reports of vitamin D and hypertension. Results During a median follow-up of 2 years, 42.6% of the cohort (n = 1047) developed hypertension. Compared with the 25-hydroxyvitamin D >30ng/ml, 25-hydroxyvitamin D <20 ng/ml was associated with a greater hypertension risk (OR: 1.225 [95% CI: 1.010 to 1.485] p = 0.04), although the association was attenuated and not statistically significant after adjusting for potential confounders (OR: 1.092 [95% CI: 0.866 to 1.377] p = 0.456). This meta-analysis included seven prospective studies for 53,375 participants using adjusted HR founded a significant association between vitamin D deficiencies and incident hypertension (HRs = 1.235 (95% CI: 1.083 to 1.409, p = 0.002)). Conclusion Lower serum 25-hydroxyvitamin D concentrations were not associated with a greater risk of incident hypertension. More research is needed to further determine the role of 25-hydroxyvitamin D in hypertension prevention and therapy.
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Emerging evidence from in vivo and in vitro studies have shown that vitamin D may play an important role in the development of diabetic retinopathy (DR), but individually published studies showed inconclusive results. The aim of this study was to quantitatively summarize the association between vitamin D and the risk of diabetic retinopathy. We conducted a systematic literature search of Pubmed, Medline, and EMBASE updated in September 2016 with the following keywords: “vitamin D” or “cholecalciferol” or “25-hydroxyvitamin D” or “25(OH)D” in combination with “diabetic retinopathy” or “DR”. Fifteen observational studies involving 17,664 subjects were included. In this meta-analysis, type 2 diabetes patients with vitamin D deficiency (serum 25(OH)D levels <20 ng/mL) experienced a significantly increased risk of DR (odds ratio (OR) = 2.03, 95% confidence intervals (CI): 1.07, 3.86), and an obvious decrease of 1.7 ng/mL (95% CI: −2.72, −0.66) in serum vitamin D was demonstrated in the patients with diabetic retinopathy. Sensitivity analysis showed that exclusion of any single study did not materially alter the overall combined effect. In conclusion, the evidence from this meta-analysis indicates an association between vitamin D deficiency and an increased risk of diabetic retinopathy in type 2 diabetes patients.
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Background: During the past decade, an increasing number of prospective studies have focused on the association between vitamin D and cardiovascular disease (CVD). However, the evidence on the relation between serum 25-hydroxyvitamin D [25(OH)D] and the risk of overt CVD is inconclusive.Objective: We performed a dose-response meta-analysis to summarize and prospectively quantify the RR of low serum 25(OH)D concentration and total CVD (events and mortality).Design: We identified relevant studies by searching PubMed and EMBASE up to December 2015 and by hand-searching reference lists. Prospective studies based on the general population and reported RRs and 95% CIs were included. A random-effects model was used to calculate the pooled RRs. Nonlinear association was assessed by using restricted cubic spline analyses.Results: A total of 34 publications with 180,667 participants were eligible for the meta-analysis. We included 32 publications (27 independent studies) for total CVD events and 17 publications (17 independent studies) for CVD mortality. We observed an inverse association between serum 25(OH)D and total CVD events and CVD mortality, and the pooled RRs per 10-ng/mL increment were 0.90 (95% CI: 0.86, 0.94) for total CVD events and 0.88 (95% CI: 0.80, 0.96) for CVD mortality. A nonlinear association was detected for total CVD events (P-nonlinear < 0.001) and CVD mortality (P-nonlinear = 0.022).Conclusion: Serum 25(OH)D concentration was inversely associated with total CVD events and CVD mortality from the observed studies.
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Background: Vitamin D deficiency has been described as being pandemic, but serum 25-hydroxyvitamin D [25(OH)D] distribution data for the European Union are of very variable quality. The NIH-led international Vitamin D Standardization Program (VDSP) has developed protocols for standardizing existing 25(OH)D values from national health/nutrition surveys. Objective: This study applied VDSP protocols to serum 25(OH)D data from representative childhood/teenage and adult/older adult European populations, representing a sizable geographical footprint, to better quantify the prevalence of vitamin D deficiency in Europe. Design: The VDSP protocols were applied in 14 population studies [reanalysis of subsets of serum 25(OH)D in 11 studies and complete analysis of all samples from 3 studies that had not previously measured it] by using certified liquid chromatography-tandem mass spectrometry on biobanked sera. These data were combined with standardized serum 25(OH)D data from 4 previously standardized studies (for a total n = 55,844). Prevalence estimates of vitamin D deficiency [using various serum 25(OH)D thresholds] were generated on the basis of standardized 25(OH)D data. Results: An overall pooled estimate, irrespective of age group, ethnic mix, and latitude of study populations, showed that 13.0% of the 55,844 European individuals had serum 25(OH)D concentrations <30 nmol/L on average in the year, with 17.7% and 8.3% in those sampled during the extended winter (October-March) and summer (April-November) periods, respectively. According to an alternate suggested definition of vitamin D deficiency (<50 nmol/L), the prevalence was 40.4%. Dark-skinned ethnic subgroups had much higher (3- to 71-fold) prevalence of serum 25(OH)D <30 nmol/L than did white populations. Conclusions: Vitamin D deficiency is evident throughout the European population at prevalence rates that are concerning and that require action from a public health perspective. What direction these strategies take will depend on European policy but should aim to ensure vitamin D intakes that are protective against vitamin D deficiency in the majority of the European population.
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Vitamin D deficiency is a major public health problem worldwide. However, most countries are still lacking data, particularly in infants, children, adolescents and pregnant women. The objective of the present report was to conduct a more recent systematic review of global vitamin D status, with particular emphasis in at risk groups. A systematic review was conducted between April and June of 2013 to identify articles on vitamin D status worldwide published in the last 10 years in apparently healthy individuals. Only studies with vitamin D status prevalence were included. If available, the first source selected was population-based or representative samples studies. Clinical trials, case-control studies, case reports or series, reviews, validation studies, letters, editorials, or qualitative studies were excluded. A total of 98 articles were eligible and included in the present report. Prevalence of vitamin D status was reported by continent. In areas with available data, the prevalence of low vitamin D status is a global problem in all age groups, in particular in girls and women from the Middle East. These results also evidenced the regions with missing data for each specific population groups, such as in infants, children and adolescents worldwide, and in most countries of South America and Africa. In conclusion, vitamin D deficiency is a global public health problem in all age groups, particularly in those from the Middle East.
Vitamin D deficiency is now recognized as a pandemic. The major cause of vitamin D deficiency is the lack of appreciation that sun exposure in moderation is the major source of vitamin D for most humans. Very few foods naturally contain vitamin D, and foods that are fortified with vitamin D are often inadequate to satisfy either a child's or an adult's vitamin D requirement. Vitamin D deficiency causes rickets in children and will precipitate and exacerbate osteopenia, osteoporosis, and fractures in adults. Vitamin D deficiency has been associated with increased risk of common cancers, autoimmune diseases, hypertension, and infectious diseases. A circulating level of 25-hydroxyvitamin D of >75 nmol/L, or 30 ng/mL, is required to maximize vitamin D's beneficial effects for health. In the absence of adequate sun exposure, at least 800–1000 IU vitamin D3/d may be needed to achieve this in children and adults. Vitamin D2 may be equally effective for maintaining circulating concentrations of 25-hydroxyvitamin D when given in physiologic concentrations.
Background: A systematic vitamin D fortification of fluid milk products and fat spreads was started in 2003 in Finland to improve vitamin D status. Objective: We investigated the effects of the vitamin D fortification policy on vitamin D status in Finland between 2000 and 2011.Design: Serum 25-hydroxyvitamin D [S-25(OH)D] concentrations of a nationally representative sample comprising 6134 and 4051 adults aged ≥30 y from the Health 2000 and Health 2011 surveys, respectively, were standardized according to the Vitamin D Standardization Program with the use of liquid chromatography-tandem mass spectrometry. Linear and logistic regression models were used to assess the change in S-25(OH)D concentrations.Results: Between 2000 and 2011, the mean S-25(OH)D increased from 48 nmol/L (95% CI: 47, 48 nmol/L) to 65 nmol/L (95% CI: 65, 66 nmol/L) (P < 0.001). The prevalence of vitamin D supplement users increased from 11% to 41% (P < 0.001). When analyzing the effect of fortification of fluid milk products, we focused on supplement nonusers. The mean increase in S-25(OH)D in daily fluid milk consumers (n = 1017) among supplement nonusers was 20 nmol/L (95% CI: 19, 21 nmol/L), which was 6 nmol/L higher than nonconsumers (n = 229) (14 nmol/L; 95% CI: 12, 16 nmol/L) (P < 0.001). In total, 91% of nonusers who consumed fluid milk products, fat spreads, and fish based on Finnish nutrition recommendations reached S-25(OH)D concentrations >50 nmol/L in 2011.Conclusions: The vitamin D status of the Finnish adult population has improved considerably during the time period studied. The increase is mainly explained by food fortification, especially of fluid milk products, and augmented vitamin D supplement use. Other factors, such as the difference in the ultraviolet radiation index between 2000 and 2011, may partly explain the results. When consuming vitamin D sources based on the nutritional recommendations, vitamin D status is sufficient [S-25(OH)D ≥50 nmol/L], and supplementation is generally not needed.