Is more prolonged sun exposure associated with healthier life habits and obesity indicators in Portuguese children?

Objectives: Sun exposure seems to have an indirect effect on the development of obesity through vitamin D synthesis in the skin, the primary source of this vitamin. The present study aimed to investigate associations among sun exposure time, obesity indicators, and lifestyle habits in children. Methods: A total of 4755 children (3–10 years; 49.86% boys) from the north, center and south-central Portugal were included in the present study. During 2016/2017 children's sun exposure time, screen time, time devoted to the practice of physical activity and active play were collected through standard questionnaires answered by parents. Statistical analyses were conducted to investigate differences among sun exposure time according to the sex, age, obesity indicators and lifestyle habits. Results: Linear regression analysis showed that sun exposure time presented a negative association with Body Mass Index (β = −0.09, 95% CI: −0.18; −0.003; p =.042), body fat % (β = −0.31, 95%; CI: −0.54; −0.07; p =.010), computer time (β = −0.08, 95% CI: −0.12; − 0.05; p <.0001) and a positive association with active play time (β = 0.22, 95% CI: 0.17; 0.27; p <.0001) and total time of physical activity practice (β = 10.01, 95% CI: 4.52; 15.20; p <.0001). Conclusions: The results reinforce the need for future guidance on the ideal sun exposure time, especially in children, who are at risk for vitamin D deficiency. Standardization of criteria for classifying optimal sun exposure time in this age group, considering the parameters that affect vitamin D status, such as age and seasonality, should be considered when planning future guidelines.