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JEPonline
Photoprotection, Solar Exposure, and Vitamin D in Active and Sedentary Eutrophic Adolescents
Patricia Ribeiro Paes Corazza1, Maiara Cristina Tadiotto1, Derick Andrade Michel1, Maria de Fátima Lopes1, Íncare Correa de Jesus1, Kátia Sheylla Malta Purim2, Neiva Leite1
1Federal University of Parana, Physical Education Department, Curitiba, Brazil, 2Positivo University, Medicine Department, Curitiba, Brazil
ABSTRACT
Corazza PRP, Tadiotto MC, Michel DA, Lopes MF, Jesus IC, Purim KSM, Leite N. Photoprotection, Solar Exposure and Vitamin D in Active and Sedentary Eutrophic Adolescents. JEPonline 2017; 20(4):76-87. The purpose of this study was to evaluate the habits of photoprotection, sun exposure, and vitamin D in active and sedentary eutrophic adolescents. A total of 33 subjects (60.6% boys) between 10 and 17 yrs of age (mean ± SD, 13.8 ± 1.8 yrs) were divided into two groups according to their physical activity history (Active Group, n=19, ≥300 min·wk-1 and Sedentary Group, n=14, <150 min·wk-1). The vitamin D concentrations were measured and data on photoprotection and sun exposure were obtained. Statistical significance was set at P<0.05. In the total sample, 38.2% of the adolescents presented vitamin D sufficiency with no difference between the Active Group (50%) and the Sedentary Group (21%, P=0.09). The Active Group had higher concentrations of vitamin D (P=0.006) and a longer time of sun exposure during the week compared to the Sedentary Group (P<0.0001). However, only one-third of the adolescents used sunscreen when practicing outdoor sports. Regarding photoprotection, 61.8% used sunscreen of which 58.8% used it only in the summer and 44.1% only once a day. Active adolescents have higher concentrations of vitamin D and are exposed more to the sun, but the vitamin D sufficiency ratio was low and similar to the sedentary adolescents. Therefore, there are risks and benefits of sun exposure, and there is the need to consider the use of photoprotection during outdoor activities.
Key Words: Activity, Adolescents, Sun Exposure, Vitamin D
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INTRODUCTION
The concentration of vitamin D depends on sun exposure with approximately 90% of the source of vitamin D being the ultraviolet B rays absorbed in the skin (15). Vitamin D levels have been shown to be a protective factor for bone health (2) and cardiometabolic diseases (6,10), which are prevented by the regular practice of physical activities that results in overall improvement in mind and body health (18,41). However, the practice of outdoor activities, despite being an important contributor to health maintenance (27), can lead to excessive sun exposure with the appearance of skin defeats or lesions of the skin (29) including the risk of developing skin cancer (4). Therefore, sun exposure needs to be performed in a controlled and balanced way to minimize the risk of sunburn, dermatoses, and skin cancer while still being able to meet the vitamin D needs (43).
Developing appropriate sun exposure habits and promoting the use of sunscreens on a regular basis are part of an educational program to prevent skin tumors (27), which have increased in recent decades (21,24). There is also the concern of maintaining vitamin D in adequate concentrations (43) as well as maintaining the appropriate body weight. In fact, excess weight may act as a barrier to penetration of ultraviolet B rays and, therefore, result in less vitamin D absorption (1,8). Ultimately, with less exercise while still being exposed to excess sun along with the skin changes that may become barriers to regular exercise in obese adolescents (31), more individuals are likely to assume the sedentary lifestyle that potentiates the development of cardiometabolic diseases in the infant-juvenile population (25).
It is emphasized that the adolescence phase is crucial for the establishment of healthy habits, and in order to reduce the risk of cardiometabolic diseases, in addition to adequate sun exposure, it is important to encourage young people to engage in regular physical activities. The World Health Organization recommends that children and youth aged 5 to 17 should accumulate at least 300 min·wk-1 of moderate to vigorous exercise for health maintenance as well as the prevention of overweight (44). However, when staying outdoors, the young people should be encouraged to take note of the exposure time and the use of sunscreen (27).
The active lifestyle, just like the use of photoprotection and the time of sun exposure, seem to influence vitamin D concentration in adolescents (17). Studies have discussed the habits of sun exposure and photoprotection of athletes (16,29), especially the adult athletes (28,36). However, there is a small number of studies that have addressed the photoprotection of juvenile athletes (9,14). In addition, no studies were found that compared adolescent athletes with their sedentary and eutrophic pairs, including the evaluation of photoprotection habits relating them to vitamin D concentrations. This means that while the analysis of routine photoprotection and sun exposure of the juvenile population is important, it is necessary to evaluate vitamin D as well. Thus, the purpose of this study was to analyze the habits of sun exposure, photoprotection, and vitamin D concentrations of active and sedentary eutrophic adolescents from the city of Curitiba (Brazil).
METHODS
Subjects
A total of 33 adolescents (20 boys and 13 girls) between 10 and 17 yrs old (mean ± SD, 13.8 ± 1.8 yrs) with a body mass index (BMI) classified as eutrophic (20.0 ± 2.25 kg·m-²) were subjects in this study. They were students of a public school in the city of Curitiba. The adolescents were divided into two groups, according to the levels of physical activity, considering: (a) ≥300 min·wk-1 moderate to vigorous physical activity (44) as the Active Group (n = 19); and (b) those with <150 min·wk-1 Sedentary Group (n = 14). The Active Group consisted of adolescents who practiced the sports modality triathlon, who performed specific training in addition to Physical Education classes in the school. The Sedentary Group consisted of adolescent subjects who participated only in the Physical Education classes.
Procedures
The study was approved by the ethics committee under the number 62963916.0.0000.5223/ 2017. All subjects signed an informed consent form prior to participate in this study. The sample selection was probabilistic for convenience.
After the diagnosis of nutritional status and physical activity levels in 820 school children from the 6th grade of elementary school to the 3rd year of high school, the students were invited to participate in the study, of which 68 performed the medical evaluation. Then the following inclusion and exclusion criteria were applied. First, the inclusion criteria were: (a) no contraindication to the tests; (b) not to use any medication that would interfere with the results of the research; (c) classification of nutritional status as eutrophic; (d) weekly exercise volume less than 150 min·wk-1 (<150 min·wk-1) for inclusion in the Sedentary Group; (e) weekly exercise volume equal to or greater than 300 min·wk-1 (≥300 min·wk-1) for inclusion in the Active Group; and (f) engaged in scheduled practice of physical exercise for a period of one year or more for the adolescents in the Active Group. Second, the exclusion criteria were: (a) using vitamin D supplementation; (b) being overweight or obese; (c) not attending all tests; (d) practiced weekly physical activities between 150-299 min·wk-1; and (e) classification of the pubertal stage p1 and p2.
After applying the inclusion and exclusion criteria, the final sample consisted of 33 adolescents. Of the students who performed the medical evaluation (N = 68): (a) 19 were excluded because they did not perform all the evaluations proposed in the study; (b) 11 were excluded because they were either overweight or obese; (c) 3 because they were in the p2 stage of pubertal development; and (d) 2 were undergoing vitamin D supplementation.
All adolescents (N = 33) were evaluated for body mass and height, which made it possible to calculate BMI. They were evaluated for the pubertal stage, according to Tanner (40). We applied questionnaires for analysis on sun protection and sun exposure (39). The levels of physical activity were determine using a self-administered physical activity checklist of Sallis et al. (33), which was adapted by Farias Junior et al. (12). In addition, the concentrations of 25-hydroxyvitamin-D (25(OH)D), by the chemiluminescence method, were dosed in the school in the presence of the parents after a 12-hr fast.
Statistical Analyses
Statistical analysis was conducted in SPSS software version 20.0. To verify the normality of the data, the Shapiro-Wilk test was used. Descriptive statistics were used to present the data in absolute frequency (n), relative (%), and mean ± SD. For the comparison between the groups, the t-test for independent samples was used. Chi-square tests and Fisher's exact test were used to test the proportions. The linear correlation coefficient of Pearson and Spearman was used to verify the correlation between the variables. The statistical significance level was set at P<0.05.
RESULTS
Table 1 shows the descriptive characteristics of the analyzed sample. The mean age of the adolescents was 13.8 yrs (± 1.8) and the body mass index was 20.0 kg·m-² (± 2.25). In total, 20 adolescents were males (60.6%). The most frequent color/race/ethnicity was white (n = 25, 75.8%), brown (n = 6, 18.2%), and black (n = 2, 6.1%) subjects. There were no significant differences between the groups for age, body mass, height, BMI, and color/race/ethnicity.
Table 1. Descriptive Data of the Subjects.
Variables / Active Group(n=19) / Sedentary Group
(n=14) / P
Age (yrs) / 13.5 ± 1.6 / 14.2 ± 2.0 / 0.271*
Body Mass (kg) / 54.7 ± 10.9 / 55.1 ± 10.7 / 0.928*
Height (m) / 1.65 ± 10.2 / 1.64 ± 10.1 / 0.878*
BMI (kg·m-²) / 19.8 ± 2.20 / 20.3 ± 2.37 / 0.461*
Vitamin D (ng·mL-1) / 31.4 ± 6.6 / 24.0 ± 5.33 / 0.001*
Color / Race / Ethnicity
n (%) / White / 16 (84.2%) / 9 (64.3%) / 0.397**
Black / 1 (5.3%) / 1 (7.1%)
Brown / 2 (10.5%) / 4 (28.6%)
BMI = Body Mass Index; * = Student's t-test; ** = Fisher’s Exact Test
In the total sample, approximately one-third of adolescents had vitamin D sufficiency (39.4%) (25(OH)D >30 ng·mL-1), with no difference between the Active Group (52.6%) and the Sedentary Group (21.4%, chi = 3.29, P=0.07). Regarding photoprotection, 63.6% stated that they used sunscreen. However, 66.6% of adolescents did not use it when playing outdoor sports. Of those who used sunscreen, 60.6% applied it only in the summer and only 27.3% used it during outdoor exercise. In addition, the application occurs only once for almost half of the adolescents (45.5%).
Table 2 shows the results of sun exposure and photoprotection habits between the groups. Sunscreen was used by 73.7% (n = 14) of the adolescents in the Active Group and 50% (n = 7) of the adolescents in the Sedentary Group. Regarding the use of sunscreen during the practice of outdoor physical activity, the use was performed in 31.6% (n = 6) of the adolescents in the Active Group and 35.5% (n = 5) of the adolescents in the Sedentary Group, without a significant difference between the two groups. In relation to the daily sun exposure that occurs from Monday to Friday, we observed that the subjects in the Active Group was more exposed to the sun versus the subjects in the Sedentary Group (48.5%, P<0.001). In addition, although the Active Group was exposed more to the sun during the weekend than the subjects in the Sedentary Group (30.2%), it was not statistically significant.
Table 2. Photoprotection and Sun Exposure Habits of Adolescents.
Active Group(n=19) / Sedentary Group
(n=14) / P
Use of Sunscreen / Yes / 14 (73.7%) / 7 (50.0%) / 0.16*
No / 5 (26.3%) / 7 (50.0%)
Use of Sunscreen during Outdoor Sports / Yes / 6 (31.6%) / 5 (35.7%) / 0.55*
No / 13 (68.4%) / 9 (64.3%)
Frequent Use of Sunglasses / Yes / 3 (15.8%) / 2 (14.3%) / 0.65**
No / 16 (84.2%) / 12 (85.7%)
Frequent Use of Cap / Yes / 3 (15.8%) / 1 (7.1%) / 0.43**
No / 16 (84.2%) / 13 (92.9%)
Daily Solar Exposure from Monday to Friday / < 2 hrs / 3 (15.8%) / 10 (71.4%) / 0.001*
2-6 hrs / 16 (84.2%) / 4 (28.6%)
Daily Solar Exposure at the Weekend / < 2 hrs / 9 (47.4%) / 8 (57.1%) / 0.57*
2-6 hrs / 10 (52.6%) / 6 (42.9%)
Exposure Time during the Summer / Up to 10 am / 4 (21.1%) / 4 (28.6%) / 0.75**
Between 10 am and 3 pm / 8 (42.1%) / 5 (35.7%)
After 3 pm / 7 (36.8%) / 5 (35.7%)
* = Chi-Square Test; ** = Fisher’s Exact Test
Finally, the active group showed a higher 25(OH)D concentration (P=0.001), but the vitamin D sufficiency ratio was low and similar to both groups. In addition, the Active Group presented longer sun exposure during the week when compared to the Sedentary Group (P=0.001).
DISCUSSION
The skin surface is large and in direct contact with the environment. It is subject to sun exposure that when exposed without protection increases the risk of developing skin cancer (38). Consequently, several studies (13,26,28,30,37) have analyzed the exposure to sun and the photoprotection of adult athletes in various sporting modalities. Other studies have evaluated sun exposure as a factor in vitamin D concentration (34) in regards to bone health (2), the prevention of cardiometabolic diseases (6), and the unfavorable results regarding vitamin D concentrations in obese individuals (7).
Factors that may be related to adiposity become a barrier to the absorption of vitamin D (1,7, 8) and/or the sedentary behavior of the obese adolescent individuals whose dermatological concerns create certain challenges to engaging in regular physical exercise (31). Therefore, analyzing the characteristics of sun exposure and vitamin D concentration in eutrophic adolescents, dividing them by their level of physical activity into either active or sedentary, was the main objective of the present study. In this way, the research allows for excluding possible interferences in vitamin concentrations D in the child and adolescent population.