Effect of vitamin D supplementation on body fat mass in elite male college athletes
Vitamin D supplementation of 25 µg/day significantly increased serum 25(OH)D levels in elite male college athletes. Vitamin D supplementation may play a role in maintaining body fat percentage in athletes in the context of reduced sporting activity.
Kawashima, I., Tsukahara, T., Kawai, R., et al. Effect of vitamin D supplementation on body fat mass in elite male college athletes. NUTR Metab (Rondo) 18, 51 (2021). https://doi.org/10.1186/s12986-021-00578-9
Commentary
This study investigated whether vitamin D supplementation has any effect on body fat percentage among elite athletes. A prospective cohort study enrolled a total of 42 elite male collegiate athletes. They underwent body composition monitoring and blood tests and were provided with 25 µg/day vitamin D3 supplement tablets. However, supplement use depended on athlete preference, and because club activities were suspended for two months due to the 2019 coronavirus outbreak during the study period, a second test, similar to the first, was conducted approximately three months later.
Participants were then divided into a non-supplemented group (without supplements, n = 15) and a supplemented group (with supplements, n = 27).
As a result, the non-supplemented and supplemented groups showed significant differences in mean body fat percentage and serum 25(OH)D levels. However, at the time of the second test, there was no significant difference between the results of both groups.
With regard to the mean change in values from the first to the second test, it was body fat percentage (1.9 and 0.2%, respectively, P = 0.02) and serum 25(OH)D level (1.7 and 7.2 ng/mL, respectively, P < 0.001 between the two groups).
However, there are serious limitations to the results of this study.
1) The grouping of participants was not random.
2) There is no investigation of seasonal changes.
3) Confirmation of supplementation depended on each athlete's self-report.
4) Athletes' food intake data was not analyzed.
5) Participants were male only.
These factors seem to make the results of the study only applicable to people in the relevant environment, as the results are subject to generalization.
