Vitamin D intake and blood 25OHD in athletes during the winter season

Abstract

We evaluated vitamin D variation in the body during winter by investigating the vitamin D intake and blood 25-hydroxyvitamin D (25OHD) of Japanese university athletes in winter. Forty-seven athletes (22 females and 25 males) were included, all belonged to the university athletic association. The survey was conducted two times (First: October, Second: March), and comparisons were made between parallel groups. Anthropometry, dietary survey, blood test, and a questionnaire were performed. There were no significant differences in any of the nutrient intake categories between measurements. Herein, the vitamin D intake of the participants was higher than that of the general Japanese population. Blood 25OHD was significantly lower (p＜0.05) in males and females at the second visit than at the first. Our results showed that while blood 25OHD decreased significantly between measurements, no significant difference in vitamin D intake was observed, suggesting that vitamin D production by exposure to ultraviolet light may have substantially affected blood 25OHD during winter. Thus, it may be necessary to increase vitamin D intake in winter than in summer when the body’s 25OHD synthesis is thought to decrease.