What impact does vitamin D have on the fitness of adolescents?



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What impact does vitamin D have on the fitness of adolescents?

The main source of vitamin D for the human body is exposure to solar radiation. Vitamin D obtained from sun exposure or through diet is present in a biologically inactive form and must undergo two hydroxylation reactions to be transformed into calcitriol, the biologically active form.

Studies from the 2000s suggested that vitamin D may play a role in regulating the innate-type immune response against microbial agents. From in vitro experiments it has been shown that 1.25 (OH) D can stimulate the production of human cathelicidin (human cathelicidin antimicrobial peptide, CAMP), a peptide with antimicrobial action, in different cell cultures.

Vitamin D supplements have been widely marketed for their alleged anticancer properties. An association between low vitamin D levels and the risk of developing certain cancers has been noted in some observational studies. However, it is unclear whether additional dietary vitamin D or supplementation affects cancer risk.

In the study: Seasonal variability of the vitamin D effect on physical fitness in adolescents, published on the Scientific reports, we see the relationship and effects of vitamin D in this particular context. We can read: "Studies investigating the relationship between vitamin D and physical fitness in youth have provided inconsistent findings.

Recent evidence indicates that the expression of receptors and vitamin D-modulated genes in young subjects has a seasonal profile. Therefore, we investigated the role of vitamin D on physical fitness across seasons in a total of 977 male adolescents.

Anthropometrics, lifestyle, dietary habits, biochemical profiles and physical fitness were studied. Multiple linear regression models, including pairwise interaction terms involving total 25-OH-vitamin D, were fitted. The interacting effect of season and total 25-OH-vitamin D had a significant influence on physical fitness performance (spring and total 25-OH-vitamin D: ß 0.19, SE 0.07, p = 0.007; summer and total 25-OH -vitamin D: ß 0.10, SE 0.06, p = 0.11; autumn and total 25-OH-vitamin D: ß 0.18, SE 0.07, p = 0.01), whereas the main effect of total 25-OH-vitamin D alone was not significant (p = 0.30).

Body fat percentage, recreational physical activity level, time spent per day gaming / TV-watching, smoking, and hemoglobin levels were also related to the physical fitness performance score. Future studies should further explore the role of seasonal-dependent effects of vitamin D on health."