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Association of sun exposure and seasonality with vitamin D levels in Brazilian children and adolescents

  • Universidade Federal do Amazonas

Abstract and Figures

Objective: This study aimed to verify vitamin D concentration in children and adolescents during the seasons of the year and to compare vitamin D concentration between children engaged in outdoor activities and those engaged in indoor activities. Methods: This is a cross-sectional study with a sample of 708 children and adolescents (aged 6-18 years), excluding 109 (16 were over 19 years old; 39 had a disease that required continuous treatment; 20 were on continuous medication; and 34 had no vitamin D data), ending with 599. The plasma concentration of 25-hydroxyvitamin D2 was measured with commercial kits following manufacturer instructions. Results: Participants who engaged in outdoor activities, as well as those who had data collected during summer and spring, had higher levels of vitamin D. According to the Poisson regression, the proportion of participants with inadequate levels of vitamin D was greater in the participants whose vitamin D was measured during spring (PR 1.15, 95%CI 1.03-1.29) and winter (PR 1.18, 95%CI 1.05-1.32). Also, a greater proportion of inadequate vitamin D was observed for those engaged in indoor activities (PR 1.08, 95%CI 1.01-1.15). Conclusions: Participants who measured the vitamin during the summer and autumn had a lower prevalence of hypovitaminosis D. Even in regions with high solar incidence throughout the year, vitamin D levels can vary significantly during the period's seasons.
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Objective: This study aimed to verify vitamin D concentration in
children and adolescents during the seasons of the year and to
compare vitamin D concentration between children engaged in
outdoor activities and those engaged in indoor activities.
Methods: This is a cross-sectional study with a sample of 708
children and adolescents (aged 6–18 years), excluding 109 (16
were over 19 years old; 39 had a disease that required continuous
treatment; 20 were on continuous medication; and 34 had no
vitamin D data), ending with 599. The plasma concentration
of 25-hydroxyvitamin D2 was measured with commercial kits
following manufacturer instructions.
Results: Participants who engaged in outdoor activities, as well
as those who had data collected during summer and spring, had
higher levels of vitamin D. According to the Poisson regression,
the proportion of participants with inadequate levels of vitamin
D was greater in the participants whose vitamin D was measured
during spring (PR 1.15, 95%CI 1.03–1.29) and winter (PR 1.18,
95%CI 1.05–1.32). Also, a greater proportion of inadequate
vitamin D was observed for those engaged in indoor activities
(PR 1.08, 95%CI 1.01–1.15).
Conclusions: Participants who measured the vitamin during the
summer and autumn had a lower prevalence of hypovitaminosisD.
Even in regions with high solar incidence throughout the year,
vitamin D levels can vary signicantly during the period’s seasons.
Keywords: Vitamin D; Children; Adolescent; Season; Epidemiology.
Objetivo: Vericar a concentração de vitamina D em crianças
e adolescentes durante as estações do ano e comparar essa
concentração entre crianças praticantes de atividades ao ar
livre e aquelas praticantes de atividades em ambiente fechado.
Métodos: Trata-se de estudo transversal com amostra de 708
crianças e adolescentes (seis a 18 anos), excluindo-se 109, pois 16
eram maiores de 19 anos; 39 tinham doença que exigia tratamento
contínuo; 20 estavam em uso de medicação contínua; e 34 não
tinham dados de vitamina D. Terminou-se, assim, com 599 pacientes.
A concentração plasmática de 25-hidroxivitamina D2 foi medida
com kits comerciais, seguindo as instruções do fabricante.
Resultados: Os participantes que realizaram atividades ao ar
livre, assim como aqueles que tiveram dados coletados durante
o verão e a primavera, apresentaram níveis mais elevados de
vitamina D. De acordo com a regressão de Poisson, a proporção
de participantes com níveis inadequados de vitamina D foi maior
naqueles cuja medição foi realizada durante a primavera (razão
de prevalência — RP 1,15, intervalo de conança — IC95% 1,03–
1,29) e o inverno (RP 1,18, IC95% 1,05–1,32). Além disso, maior
proporção de vitamina D inadequada foi observada para aqueles
envolvidos em atividades internas (RP 1,08, IC95% 1,01–1,15).
Conclusões: Participantes que mediram a vitamina durante o verão e
o outono tiveram menor prevalência para hipovitaminoseD. Mesmo
em regiões com alta incidência solar ao longo do ano os níveis de
vitamina D podem variar signicativamente durante as estações.
Palavras-chave: Vitamina D; Criança; Adolescente; Sazonalidade;
*Corresponding author. Email: (P. R. Oliosa)
aUniversidade Federal do Espírito Santo, Vitória, ES, Brazil.
bInstituto Federal do Espírito Santo, Vitória, ES, Brazil.
cUniversidade Federal do Amazonas, Manaus, AM, Brazil.
Received on October 24, 2021; approved on May 06, 2022.
Association of sun exposure and seasonality with
vitamin D levels in Brazilian children and adolescents
Associação da exposição solar e da sazonalidade com os níveis
de vitamina D em crianças e adolescentes brasileiros
Polyana Romano Oliosaa,* , Eduardo Magno Romano Oliosab ,
Rafael de Oliveira Alvimc , Carmem Luiza Sartórioa ,
Divanei dos Anjos Zaniquelia , José Geraldo Milla
Sun exposure and vitamin D levels
Rev Paul Pediatr. 2023;41:e2021361
Brazilian studies demonstrate a high prevalence of low vita-
min D concentration in children and adolescents.1-4 Due to its
activity in human metabolism, vitamin D is also categorized
as a hormone.5,6 It acts in several metabolic pathways, such as
the development of muscle mass and bones7 and inuencing
the concentration of lipid fractions,8 blood pressure,9 and other
cardiovascular factors.10-12 Exposure of the skin to solar ultra-
violet (UV) radiation is the elementary mechanism of vitamin
D synthesis in humans.13,14
In our species, only 10–20% of the vitamin D necessary
for proper function of the organism comes from diet. e cen-
tral dietary sources are vitamin D3 (cholecalciferol, of animal
origin, present in oily sh from cold and deep water, such as
tuna and salmon) and vitamin D2 (ergosterol, of plant origin,
present in edible fungi). e remaining 80–90% depends on
endogenous synthesis,15 which mainly requires ultraviolet B
(UVB) radiation at wavelengths between 290 and 315 nm.
Due to the position of the axis where the Earth translates
around the sun, the more a location is displaced from the
Equator, the greater the thickness of the atmospheric layer
that sunlight must pass through, which causes attenuation in
various wavelengths, including UVB radiation. is incidence
angle of sunlight on Earth (solar zenith) also changes over the
seasons, being greater in winter, when the amount of UVB rays
reaching the Earth’s surface is lower.16
erefore, vitamin D synthesis in the human body depends
on a number of causes, including geographical factors (e.g., solar
elevation, ozone, cloudiness, and albedo), individual human
factors, such as skin darkness, outdoor activities, and age, as
well as genetic factors.17
Sola etal.18 showed that in the solar hours between 10:00
and 14:00, vitamin D production reaches higher values in rela-
tion to the rest of the day. At these times, greater irradiance is
also available, as the zenith angle is smaller, which means that
the irradiance suers less interference from the atmosphere.
No Brazilian study has focused on the inuence of time
spent with outdoor activities or the seasonality on the level of
vitamin D. us, the aim of this study was to verify vitamin D
concentration in children and adolescents during the seasons
of the year and to compare vitamin D concentration between
children engaged in outdoor activities and those engaged in
indoor activities.
is is a cross-sectional, descriptive, and quantitative study
including 599 children and adolescents, aged 6–18 years old,
enrolled in public schools in the municipality of Serra/ES
(latitude: 20°7’46”S/ longitude: 40°18’29” West). All participants
also attended a social project named “Estação Conhecimento”
(Knowledge Station) designed to oer complementary aca-
demic, cultural, and sports activities. e present work is part
of more comprehensive research entitled “Determinants of ele-
vated blood pressure in children and adolescents of dierent
ancestry.” is is a sample of children and adolescents enrolled
in the institution called Estação Conhecimento. e plan was
that all participants enrolled in the institution from July 2018
to December 2020 would be invited to participate (n=1000).
However, with the COVID-19 pandemic, the collection took
place from July 2018 to November 2019, and 708 participants
of the institution were invited to the study. Among them, 199
were excluded: 16 participants were over 19 years old, 39 had a
disease that required continuous treatment, 20 were on contin-
uous medication, and 34 had no vitamin D data. erefore,the
nal sample had 599 participants.
A dedicated sta including nutritionists, nurses, and psy-
chologists developed a semi-quantitative form with questions
on demographic, socioeconomic, health, lifestyle, and physical
activity aspects. e form was applied by a trained interviewer
on the same day as blood was withdrawn (BD Vacutainer/
EDTA). Blood samples were centrifuged in the same place as
its collection, and plasma aliquots were sent to a central labora-
tory (Laboratório Tommasi) to measure plasma concentration
of vitamin D. e plasma concentration of 25-hydroxyvitamin
D2 was measured with commercial kits following the manu-
facturer’s instructions.
e 25-hydroxyvitamin D classication was performed
as follows: vitamin D deciency dened as 25(OH)D below
20 ng/mL, insuciency in 25(OH)D of 21–29 ng/mL, and
suciency in 25(OH)D above 30 ng/mL.19 For the analyses,
dichotomous vitamin D was used, with 30 ng/mL being con-
sidered adequate and below <30 ng/mL inadequate.
Body mass index (BMI) was calculated as the ratio between
weight and height squared (kg/m2). BMI was classied according
to the standards of the World Health Organization (WHO).20
As this is a cross-sectional study, it is noteworthy that the
classications of the seasons of the year were determined accord-
ing to the months of data collection. us, the classication of
seasons was stratied as follows: summer, taking into account
the months of December, January, and February; autumn,
the months of March, April, and May; winter, the months of
June, July, and August; and spring, the months of September,
October, and November.21
Children and adolescents answered the following question
on the questionnaire: “What activity do you perform at the
Estação Conhecimento?” e possible answers were related
to sports and cultural modalities, being carried out indoors
Oliosa PR et al.
Rev Paul Pediatr. 2023;41:e2021361
(judo and music) and outdoors (swimming, athletics, sports
initiation, and soccer). ese children and teenagers spent
the entire period in activity, inside the classroom or outside,
with an average of 3 h without contact with the sun (when
activities were conducted indoors) or in contact with the sun
(when activities were outdoors), and the frequency of going
to the institution was 3 days a week. Race/color was classi-
ed according to the Brazilian Institute of Geography and
Statistics.22 All the children were of low socioeconomic class,
and there was no measurement of food consumption related
to vitamin D and no child was taking vitamin D replace-
ment (the questionnaire had questions about medications
and supplements used).
e database construction and statistical analyses were done
using the SPSS for Windows, version 20.0, statistical software
package. For descriptive analysis, the chi-square test was used
and comparison between groups used ANCOVA adjusted for
confounding variables. e association among vitamin D de-
ciency, seasons, and sun exposure was determined by Poisson
regression with robust variance, expressed as prevalence ratios
(PR) and condence intervals of 95%.
To make the maps, the ArcGIS program was used with data
from the NISR (National Institute for Space Research, Brazil)
database, from the year 2018, version 10.7, which expressed
the available solar radiation (Wh/m2/day) in the State of
Espírito Santo, making it possible to visualize the changes in
solar incidence in the four seasons of the year in ES and also
in the Serra Municipality.
e present study is part of a more comprehensive research
entitled “Determinants of high blood pressure in children and
adolescents from dierent ancestry” and was approved by the
institutional Human Research Ethics Committee (CAAE:
30385014.8.0000.5060, no. 725.488). Participants were invited
and informed about the objectives of the study. Datacollec-
tion was obtained after the written informed consent was
signed by parents or guardians of all participants. Adolescents
(12–19years) also signed the assent form.
e sample consisted of 599 children and adolescents aged 6–19
years, 42.1% female. Among the participants, 62 (10.4%) were
classied with decient vitamin D concentration, 257 (42.9%)
insucient, and 280 (46.7%) with sucient. us, inadequate
vitamin D concentration (<30 ng/mL) was observed in 53.3%
(n=319) of the participants. Of the total, 413 (74.28%) partic-
ipants engaged in outdoor activities. Even so, it was observed
that 53.3% (n=319) of the participants presented inadequate
vitamin D levels.
Table 1 shows the distribution of variables by vitamin D
concentration. Noteworthy, winter was the season that vita-
min D reached the highest proportion of inadequacy, whereas
summer was the season with the lowest proportion.
It was observed that the highest percentage of participants par-
ticipated in the research during the winter season, 39.56% (n=220).
According to the Poisson regression, the proportion of par-
ticipants with inadequate levels of vitamin D was 15% and
18% greater in the participants whose vitamin D was measured
during spring and winter, respectively. Similarly, the proportion
of children and adolescents with inadequate levels of vitamin D
was 8% greater for those engaged in indoor activities (Table 2).
Table 1. Description of the sample stratied by vitamin
D status.
Total Adequate Inadequate p-value
n (%) n (%) n (%)
Spring 154 (25.7) 63 (22.5) 91 (28.5)
Summer 43 (7.2) 26 (9.3) 17 (5.3)
Autumn 169 (28.2) 101 (36.1) 68 (21.3)
Winter 233 (38.9) 90 (32.1) 143 (44.8)
Sun exposure
Indoor 143 (25.7) 55(20.3) 88 (30.9) 0.004
Outdoor 413 (74.3) 216 (79.7) 197 (69.1)
Age range
6–8 113 (18.9) 59 (21.1) 54 (16.9)
9–11 203 (33.9) 97 (34.6) 106 (33.2)
12–14 211 (35.2) 99 (35.4) 112 (35.1)
15–18 72 (12) 25 (8.9) 47 (14.7)
BMI status
weight 20 (3.3) 6 (2.1) 14 (4.4)
Eutrophy 436 (72.8) 213 (76.1) 223 (69.9)
Overweight 110 (18.4) 213 (76.1) 63 (19.7)
Obesity 33 (5.5) 14 (5.0) 19 (6.0)
White 164 (27.4) 84 (30.0) 80 (25.1)
0.112Black 178 (29.7) 72 (25.7) 106 (33.2)
Brown 257 (42.9) 124 (44.3) 133 (41.7)
Chi-square test. p-value signicant when <0.05 (indicated in bold).
Theseasons of the year were classied according to the month
of data collection. Activities: indoor (music and judo) and outdoor
(swimming, soccer, athletics, sports initiation). Vitamin D breakpoints:
adequate 30 ng/mL and inadequate below <30 ng/mL.
Sun exposure and vitamin D levels
Rev Paul Pediatr. 2023;41:e2021361
Table 3 shows the mean concentration of vitamin D strat-
ied by indoor and outdoor activities. Of the total sample
participants, 413 (74.28%) practiced outdoor activities, and
143(25.71%) practiced indoor activities. Even with the major-
ity of the sample practicing outdoor activities, it was observed
that 53.3% (n=319) of the participants had an inadequate con-
centration of vitamin D (below 30 ng/mL).
Figure 1 shows the mean values of vitamin D concen-
tration according to the season. Interestingly, those children
and adolescents who had vitamin D measured during winter
(28.2±7.5ng/dL and spring (29.6±9.3 ng/dL) presented lower
vitamin D levels than those whose vitamin D was measured
during summer (35.1±9.7 ng/dL).
Figure 2 illustrates the maps showing the frequency of solar
incidence throughout 2018, in the analysis carried out for the
State of Espírito Santo, and this was stratied according to the
four seasons of the year from the global horizontal radiation
available in the geographical region analyzed in Watt-hour
energy per square meter per day (Wh/m2/day).
It is noteworthy that the analysis was carried out based
on 2018, and data collection took place from 2017 to 2019.
However, as the Earth’s inclination does not vary much per
year, the year described can be used as a basis.
e maps show how the solar frequency distribution was
in the state of Espírito Santo as well as in the municipality of
Serra, where the research was developed. e main objective
of the maps is to demonstrate how there is a variety of solar
frequency in the dierent months of the year, even in a State
that, being in Brazil, a country close to the equator, implies
that an optimal frequency of solar incidence should occur
during the entire year.
According to Planck,23 energy is directly proportional
to frequency and the wavelength is inversely proportional
Table 2. Prevalence ratio of vitamin D inadequacy, according to seasons and sun exposure status.
Crude Adjusted
PR (95%CI) p-value PR (95%CI) p-value
Summer 1 ---- 1 ----
Autumn 1.01 (0.89–1.13) 0.933 1.01 (0.90–1.14) 0.989
Spring 1.14 (1.02–1.28) 0.020 1.15 (1.03–1.29) 0.010
Winter 1.16 (1.03–1.29) 0.010 1.18 (1.05–1.32) 0.004
Sun exposure
Outdoor 1 ---- 1 ----
Indoor 1.09 (1.03–1.16) 0.003 1.08 (1.01–1.15) 0.020
PR: prevalence ratio; 95%CI: 95% condence interval. Vitamin D inadequacy: <30 ng/mL. Adjusted model: age range, race/color, and sex.
p-values in boldface are signicant.
Table 3. The mean concentration of vitamin D stratied
by indoor and outdoor activities.
Activities Vitamin D (ng/mL) p-value
n Mean (SD)
Indoor 143 29.4 (9.68)
0.034Outdoor 413 31.4 (9.35)
Total 556 30.9 (9.51)
*ANCOVA test (variable adjusted for age, sex, race/color, and seasons):
p-value signicant when 0.05 (indicated in bold). Activities: indoor
(judo and music) and outdoor (swimming, athletics, sports initiation,
and soccer).
Vitamin D (ng/mL)
Summer Autumn
Winter Spring
Figure 1. Vitamin D concentration according to the
seasons. Marginal mean estimations adjusted for age,
sex, race/color, and sun exposure status. ANCOVA test
(variable adjusted for age, sex, race/color, and indoor
and outdoor activities). *Signicant lower than summer
(p<0.05). Seasons stratication by months of the year:
summer – December, January, and February; autumn –
March, April, and May; winter – June, July, and August;
spring – September, October, and November.
Oliosa PR et al.
Rev Paul Pediatr. 2023;41:e2021361
Figure 2. Changes of solar incidence in the seasons of the year in Espírito Santo. A: Spring; B: Summer; C: Autumn;
D: Winter.
4767,000000 – 5022,333333
5026,000000 – 5171,000000
5172,000000 – 5317,000000
5319,000000 – 5516,333333
5521,333333 – 5812,000000
5065,000000 – 5574,000000
5584,333333 – 5736,333333
5742,666667 – 5871,666667
5873,000000 – 6036,000000
6042,000000 – 6323,666667
3682,666667 – 3870,000000
3872,666667 – 3945,333333
3946,666667 – 4003,333333
4004,000000 – 4072,666667
4075,000000 – 4273,333333
4014,666667 – 4161,666667
4163,666667 – 4239,000000
4240,000000 – 4318,000000
4321,666667 – 4421,666667
4425,000000 – 4615,333333
015 30 60 90 120
Kilometers 0
010 20Km
010 20Km
50 10 20Km
010 20Km
15 30 60 90 120
015 30 60 90 120
015 30 60 90 120
Sun exposure and vitamin D levels
Rev Paul Pediatr. 2023;41:e2021361
tofrequency. us, solar energy is closely related to the wave-
length and, therefore, in regions that have greater solar energy
availability, the wavelength will be predominantly shorter (with
greater availability of UVB radiation). e evolution of solar
energy availability over the months of the year, stratied by
seasonality. e darker the area on the graph, the greater the
incidence of sunlight, which means greater availability of sun-
light under the demarcated region, favoring the conversion of
vitamin D in the skin.
is is the rst study that was carried out in Brazil demonstrat-
ing the frequency of solar incidence in the country, correlating
with vitamin D concentrations in children and adolescents, as
well as demonstrating how important the contact of this pop-
ulation with the sun is, in order to activate vitamin D.
From the data visualized in this study, we emphasize the
importance of tests related to vitamin D being compared
between populations and even in a clinical way, being col-
lected in the same periods of the year, taking into account the
seasonal changes in solar incidence, and consequently in the
metabolism of vitamin D in the human body.
Brazilian studies1-4 show an average of 50% of the pop-
ulation studied with vitamin D insuciency, which corrob-
orates the present study, which found 46.7%. Araújo etal.4
and Lopes etal.3 identied an association between overweight
and reduced vitamin D concentration, the rst study showed
that, in males, adolescents classied as overweight/obese were
2.4 times more likely to have hypovitaminosis than eutrophic
adolescents, this association was not found in the present
study, since more than 70% of the population was classied as
eutrophic and because it is an active population. According to
Peters etal.,2 only 27.9% of the assessed adolescents practiced
outdoor physical activity, with vitamin D insuciency being
found in 60% of the sample. In the present study, 74.3% of
those eligible had been exposed to the sun through the practice
of outdoor physical activity, and the prevalence of vitamin D
insuciency was 42.9% and we can observe that individuals
who performed indoor activities had a prevalence of 8% more
of hypovitaminosis D.
A major source of vitamin D for most humans comes from
skin exposure to sunlight, typically between 10:00 and 15:00 h
in the spring, summer, and fall.6,15 Vitamin D produced in the
skin may last at least twice as long in the blood compared with
ingested vitamin D.24 When an adult wearing a bathing suit
is exposed to one minimal erythemal dose of UV radiation (a
slight pinkness to the skin 24 h after exposure), the amount of
vitamin D produced is equivalent to ingesting between 10,000
and 25,000 IU.25 A variety of factors reduce the skin’s produc-
tion of vitamin D3, including increased skin pigmentation,
aging, and the topical application of sunscreen.25,26 Typically,a
human body requires about 3000–5000 IU vitamin D daily
under the usual load.27
A study carried out in Poland with children aged 4–6 years
analyzed the concentration of vitamin D in children and found
that the best time of year to acquire vitamin D would be from
May to September, with exposure having to take place between
10:00 and 15:00 h, for 15 min with the least amount of cloth-
ing, leaving the skin more exposed.28 e present study observed
that children who spend more time doing outdoor activities
are not less likely to have low concentrations of vitamin D
(p<0.05), and the proportion of participants with inadequate
vitamin D was 15% and 18% greater in the participants whose
vitamin D was measured during spring and winter, respectively.
Most of the participants in this study had their data col-
lected in the winter, and an explanation for this fact is that
the students’ vacation period takes place in the summer, and
that “Estação Conhecimento” observes the school vacation
period; therefore, it closes its activities in mid-December and
only returns in mid-February, and summer is determined as
December to March. However, these data are also important
since, theoretically, in Brazil, there would not be such a huge
change in solar incidence, to the point of needing to supple-
ment vitamin D as in Northern countries.29
e mountain region of Espírito Santo has a higher altitude,
and this inuences the increase in solar irradiance. However,
the region is composed of much topographic unevenness,
such as hills, which allows for the formation of clouds due to
the humidity coming from the ocean, favoring the reduction
of solar radiation. e coastal region of the State where the
municipality of Serra is located has an annual average of solar
irradiance between 4,701 and 4,850 Wh/m2/day.30 Solar irradi-
ance in the region is more inuenced by the solar zenith angle,
which varies during the day and over the months. emonths
with the highest solar radiation value in the state of Espírito
Santo were the months that represent the summer period in
the southern hemisphere of the planet. In contrast, the months
with the lowest incidence were the winter months.
e months that comprise the summer present greater
solar irradiance and with that the production of vitamin D is
accentuated. is is evident when the average concentration
of vitamin D is compared with the values of solar irradiance.
In the summer, the average concentration of vitamin D was
35.10 ng/mL while the solar radiation in that same period in
2017 reached 6,500–7,000 Wh/m2/day. Winter is the sea-
son of the year when the region receives less solar radiation
and consequently the production of vitamin D is attenuated.
Oliosa PR et al.
Rev Paul Pediatr. 2023;41:e2021361
esolar radiation presented maximum values between 5,001
and 5,500 Wh/m2/day. Such values show that an amount of
energy was received from the sun, and this directly aects the
average production of vitamin D in the same period, which
was 28.24 ng/mL.
As for the limitations of the study, we can list the sample,
as the collection of vitamin D was performed only once for
each child, not being a longitudinal analysis but a random
sample. However, the study proves to be important due to the
survey of data carried out and associations made, other authors
being able to carry out longitudinal studies and with represen-
tative samples of the population, using the same methodology
addressed. Another limitation would be related to the eective
time that the child or adolescent spends in the sun; however,
the identication of the importance of this contact, through
the present study, raises the question about the need to pro-
vide means for the child-juvenile population, to expose them-
selves to the sun more often, and to facilitate the activation of
vitamin D in the body. In addition, we did not assess dietary
intake of vitamin D, but it is known that vitamin D intake
from food is incipient and the major factor that impacts its
concentration is contact with the sun.
Even in a Latin American country, vitamin D concentra-
tion should be taken into account and frequently evaluated in
children and adolescents. An important fact raised was the fact
of collecting data from scientic studies or clinical analyses,
according to seasonality, as it interferes with the concentration
of vitamin D. It is extremely important that greater exposure
to the sun is encouraged and that schools make available free
time for children to be exposed to the sun, through outdoor
physical activity, for example, and that governments provide
means for this, since children and adolescents who are more
exposed to the sun have a higher concentration of vitamin D.
is study initiates the discussion on the need to develop
public policies for vitamin D supplementation in addition to
public policies that encourage contact with the sun through
outdoor activities for the specic public, even in a country that
receives sun all year round.
VALE nanced the study with scholarships, purchase of mate-
rials, equipment, and provided the study space; the Fundação
Espírito-Santense de Tecnologia was responsible for managing
the resources; Tommasi Laboratory analyzed the biochemical
data and granted the results.
Conflict of interests
e authors declare there is no conict of interests.
Authors’ contribution
Study design: Oliosa PR, Alvim RO, Mill JG. Data collection:
Oliosa PR, Zaniqueli DA. Data analysis: Oliosa PR, Oliosa
EMR, Zaniqueli DA, Alvim RO. Manuscript writing: Oliosa
PR, Oliosa EMR, Alvim RO, Satório CL. Manuscript revision:
Oliosa PR, Alvim RO, Satório CL, Zaniqueli DA, Mill JG.
Study supervision: Oliosa PR, Zaniqueli DA, Mill JG.
e database that originated the article is available with the
corresponding author.
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... The primary source of vitamin D in humans is its synthesis in the skin, requiring sufficient exposure to UVB radiation, the source of which is sunlight. However, it is insufficient not only in our latitude but also in countries with higher insolation, at least during the autumn and winter [6][7][8][9]. Another important source of vitamin D is food products. ...
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The aim of the study was to investigate the effects of seasonal variability of insolation, the implementation of new recommendations for vitamin D supplementation (2018), and the SARS-CoV-2 pandemic lockdown (2020) on 25(OH)D concentrations in children from central Poland. The retrospective analysis of variability of 25(OH)D concentrations during the last 8 years was performed in a group of 1440 children with short stature, aged 3.0–18.0 years. Significant differences in 25(OH)D concentrations were found between the periods from mid-2014 to mid-2018, from mid-2018 to mid-2020, and from mid-2020 to mid-2022 (medians: 22.9, 26.0, and 29.9 ng/mL, respectively). Time series models created on the grounds of data from 6 years of the pre-pandemic period and used for prediction for the pandemic period explained over 80% of the seasonal variability of 25(OH)D concentrations, with overprediction for the first year of the pandemic and underprediction for the second year. A significant increase in 25(OH)D concentrations was observed both after the introduction of new vitamin D supplementation guidelines and during the SARS-CoV-2 pandemic; however, the scale of vitamin D deficiency and insufficiency was still too high. Time series models are useful in analyzing the impact of health policy interventions and pandemic restrictions on the seasonal variability of vitamin D concentrations.
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Vitamin D insufficiency and deficiency are highly prevalent in adult football players and can exceed 80% even in regions with high insolation; however, the treatment of this condition is often complicated. The aim of the present study was to examine the prevalence of vitamin D insufficiency and deficiency in youth Russian soccer players and the efficacy of its treatment. Participants were 131 young male football players (age 15.6±2.4 years). Low vitamin D levels were observed in 42.8% of the analyzed participants. A dietary supplement of 5,000 IU cholecalciferol was administered for two months. After the treatment, an increase in vitamin D concentration was observed in 77.0% of participants, and in 73.9% the post-treatment values were within the reference range. Serum concentration of vitamin D increased by 126.9% during the first month of treatment with vitamin D deficiency and insufficiency being successfully treated in 85.7% of the football players. During the second month of treatment, serum concentration of vitamin D in both groups dropped by 27%. In summary, the prevalence of vitamin D deficiency was high in young Russian football players. Furthermore, it was indicated that the daily usage of cholecalciferol in small doses was an effective and well-tolerated treatment for vitamin D insufficiency. No linear dependency between the duration of treatment and increase in vitamin 25(OH)D concentration was observed. Keywords: vitamin D3; cholecalciferol; Vitamin D deficiency; treatment of vitamin D3 deficiency; football
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Introduction: increased vitamin D deficiency occurs together with obesity and the association between these conditions has been observed. Objective: to assess the nutritional status of vitamin D and metabolic profile in adolescents and adults with obesity, and the relationship between complications arising from severe class of obesity with vitamin D nutritional status, and to compare the differences between these groups. Methods: observational comparative study. Population comprises adolescents and adults with severe obesity. Waist circumference (WC) and body mass index (BMI) were measured. Analysis of vitamin D (25(OH)D), lipid profile, C-reactive protein (CRP), blood glucose, fasting insulinemia, insulin sensitivity, blood pressure and diagnoses of nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome (MS) were performed. Results: a total of 60 adolescents (G1) and 68 adults (G2) were evaluated. The percentage of vitamin D inadequacy was observed in 90% in G1 and 79.4% in G2. There was a negative and significant correlation of BMI with the values of 25(OH)D in the group of adults (r = -0.244; p = 0.045). Individuals with inadequacy of vitamin D showed higher values of CRP in both groups (p = 0.000). HOMA-IR showed a negative correlation with 25(OH)D in G1 (r = -0.832; p = 0.000) and G2 (r = -0.589; p = 0.000). The inadequacy of this vitamin showed association with high total cholesterol in G1 (p = 0.029) and higher values of LDL-c in G2 (p = 0.003). Conclusion: high prevalence of deficiency and insufficiency of vitamin D were observed, associated with metabolic changes both in obese adults and adolescents. It is necessary to develop strategies for the prevention and control of obesity and vitamin D deficiency.
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Background: Hypovitaminosis D is a frequent problem in the world and can be influenced by several factors. Objective: To estimate the prevalence of hypovitaminosis D and associated factors in adolescent students of a capital city of northeastern Brazil. Methods: Cross-sectional epidemiological study assessing 220 school adolescents of both sexes aged 15 to 19 years. A questionnaire was applied to assess sociodemographic (skin color, mother's education and receiving social benefits) and behavioral data (number of hours of sleep per day, sun exposure, physical activity and dietary vitamin D intake). Anthropometric nutritional status was assessed by BMI (body mass index) for age. Serum 25 (OH) D concentrations, PTH and serum calcium were measured by blood samples. We identified individuals with hypovitaminosis D as those with 25 (OH) D < 30 ng/dL. The analysis of factors associated with hypovitaminosis D was performed by simple and multivariate Poisson Regression. Results: The prevalence of hypovitaminosis D was 57.3%. The female population had a significantly higher prevalence than the male. In the final adjusted model, the variable independently associated with hypovitaminosis D in females was the lowest serum calcium concentrations, and for males it was BMI, in which adolescents who had overweight/obesity were 2.4 times more likely to have hypovitaminosis D than the eutrophic ones. Conclusions: The present study found a high prevalence of hypovitaminosis D in the analyzed population, especially in female adolescents. In addition, the factors independently associated with hypovitaminosis D were found to be overweight/obese in boys and low calcium concentrations in girls.
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The first edition of the Brazilian Solar Energy Atlas was launched in 2006 based on ten years of data from the GOES series satellites and the BRAZIL-SR physical model of radiative transfer, validated with data observed at 98 weather stations operated by INMET (National Institute of Meteorology) and spread throughout the country. At the time of the launch, the SONDA network (Sistema de Organização Nacional de Dados Ambientais), operated by INPE, had recently entered into operation and contributed to the validation process with only three years of solarimetric data of the three components of solar irradiation on the surface: global horizontal, direct normal and diffuse. This pioneering edition of the Atlas was an important milestone in the history of solar energy in Brazil and is still employed today by several researchers and entrepreneurs in solar energy. After more than ten years, the Center for Terrestrial System Science (CCST) of the National Institute for Space Research (INPE), through its Laboratory for Modeling and Studies of Renewable Energy Resources (LABREN), is pleased to publish the second edition, expanded and revised, of the Brazilian Atlas of Solar Energy. It is an example of cooperative work between INPE and researchers from various institutions in Brazil: the Federal University of São Paulo (UNIFESP), the Federal University of Santa Catarina (UFSC), the Federal Technological University of Paraná (UTFPR), and the Federal Institute of Santa Catarina (IFSC). For this new edition, more than 17 years of satellite data have been used. Several advances have been implemented in the BRAZIL-SR radiative transfer model's parameterization, aiming to improve further the reliability and accuracy of the database produced and made available for public access. In addition to these advances, the new version contains analyses on confidence levels, on the spatial and temporal variability of the solar resource, and presents scenarios for the use of various solar technologies. Although the focus of the Atlas is on the energy area, the The data presented also serves users in several other areas of knowledge, such as meteorology, climatology, agriculture, hydrology, and architecture. This Atlas had the National Institute of Science and Technology for Climate Change (INCT-MC) scientific contribution through processes CNPq 573797/2008-0 and FAPESP 2008/57719-9, which supported the research phase, consolidation, and its final assembly. We can also thank and share this moment with the Petrobras Research Center (CENPES) which, through the ANEEL PD-0553-0013/2010 Project with INPE, provided the crucial financial support for the improvement of the BRAZIL-SR model, as well as for the expansion, operation, and maintenance of the SONDA solarimetric network. The credits are also addressed to the Brazilian Research Network on Global Climate Change, through the FINEP / Rede CLIMA 01.13.0353-00 agreement, for the support in the rounds phase of the model, and to other INPE colleagues, particularly the Laboratory of Meteorological Instrumentation (LIM), the Center for Weather Forecasting and Climate Studies (CPTEC), which provided logistical support to this work since the first edition of the Atlas. We are also grateful for the institutional support of the National Electrical Energy Agency (ANEEL) and the International Solar Energy Society (ISES) for recognizing the scientific merit of this publication as an important milestone for the penetration of solar technology in Brazil. Translated with (free version)
According to Polish guidelines, children need a daily dose of 600–1000 I·U. vitamin D, which could be skin-synthesized in the period May to September, after at least 15 min solar exposure between 10 am and 3 pm with uncovered forearms and lower legs. In Poland, doctors only prescribe oral supplementation to infants and small children up to 2 years old, rarely for the older children. Numerical estimates of the daily amount of vitamin D (expressed in I.U. vitamin D taken orally) due to the solar exposure for preschoolers have been made on the basis of an observation campaign in Warsaw, Poland. In the period from April to September, the observations of children's clothing of age 4–6 years and the measurements of UV index were carried out in the kindergarten playground and a nearby park (52.31oN, 21.06°E). It appears, that longer exposures (~45 min) are needed to gain the recommended dose. However, the estimation is burden with large uncertainties. The alternative scenario is to allow children to play outside for as long as possible without getting sunburn, i.e. until the personal erythemal threshold is reached. Then, sunscreens should be applied.
Background: Prevalence of cardiometabolic risk factors is increasing and vitamin D insufficiency/deficiency has become a worldwide public health problem, even in tropical countries. Therefore, we identified the prevalence of hypertriglyceridemic waist phenotype (HWP) and evaluate its relationship with vitamin D insufficiency/deficiency. Methods: A cross-sectional study with 378 children aged 8 and 9 enrolled in all urban schools in the city of Viçosa, MG, Brazil. Anthropometric measurements, body composition (dual energy X-ray absorptiometry), biochemical tests and clinical evaluation were performed. Poisson regression was used to analyze the association between vitamin D and HWP. Results: Prevalence of HWP was 16.4%. This prevalence was higher among children with vitamin D insufficiency and deficiency and in those with a greater number of other cardiometabolic risk factors. Multiple regression analysis showed that children with vitamin D insufficiency and deficiency had, respectively, prevalence 85% (95% CI: 1.03-3.30) and 121% (95% CI: 1.11-4.45) higher of HWP than the vitamin D sufficiency group. Conclusion: Vitamin D insuffiency and deficiency were associated with a higher prevalence of HWP among children, regardless of the presence of other cardiometabolic risk factors, indicating an additional risk of inadequate vitamin D status to cardiometabolic health in childhood.
North American and European authorities have identified thresholds up to 50 nmol/L serum 25-hydroxyvitamin D (25[OH]D) as optimal for pediatric vitamin D status. These recommendations are relative to skeletal endpoints, as vitamin D plays a pivotal role in bone mineral content (BMC) accretion. Suboptimal vitamin D consumption during youth may therefore hinder BMC acquisition, and contribute to an increased fracture risk. Though vitamin D requirements range between 400 and 800 IU/day, not all children achieve this. To encourage adequate vitamin D consumption, strategies such as supplementation, food labeling, and fortification, are currently being investigated. There is moderate support for the role of vitamin D supplementation on adolescent BMC accrual; however, factors such as age, maturation, population ancestry, and latitude, are not consistently accounted for across studies. Vitamin D is also linked with extraskeletal endpoints (e.g., muscle mass/function, adiposity, and metabolic health) in children, but the cross-sectional data do not necessarily align with results from experimental trials. Based on the evidence currently available, there is no need for a revision of the pediatric vitamin D recommendations at this time. Additional trials are required, however, to build upon the hypothesis-generating observational data, and to provide evidence for future vitamin D requirements across the globe.
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.
Vitamin D deficiency is now recognized as an epidemic in the United States. The major source of vitamin D for both children and adults is from sensible sun exposure. In the absence of sun exposure 1000 IU of cholecalciferol is required daily for both children and adults. Vitamin D deficiency causes poor mineralization of the collagen matrix in young children's bones leading to growth retardation and bone deformities known as rickets. In adults, vitamin D deficiency induces secondary hyperparathyroidism, which causes a loss of matrix and minerals, thus increasing the risk of osteoporosis and fractures. In addition, the poor mineralization of newly laid down bone matrix in adult bone results in the painful bone disease of osteomalacia. Vitamin D deficiency causes muscle weakness, increasing the risk of falling and fractures. Vitamin D deficiency also has other serious consequences on overall health and well-being. There is mounting scientific evidence that implicates vitamin D deficiency with an increased risk of type I diabetes, multiple sclerosis, rheumatoid arthritis, hypertension, cardiovascular heart disease, and many common deadly cancers. Vigilance of one's vitamin D status by the yearly measurement of 25-hydroxyvitamin D should be part of an annual physical examination.