Journal of Nutritional Science and Vitaminology
Online ISSN : 1881-7742
Print ISSN : 0301-4800
ISSN-L : 0301-4800
Regular Paper
Vitamin D Status in Japanese Young Women in 2016–2017 and 2020: Seasonal Variation and the Effect of Lifestyle Including Changes Caused by the COVID-19 Pandemic
Naoko TSUGAWAAkiko KUWABARAHonami OGASAWARAMayu NISHINOKimie NAKAGAWAMaya KAMAOHiroshi HASEGAWAKiyoshi TANAKA
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Supplementary material

2022 Volume 68 Issue 3 Pages 172-180

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Abstract

Avoidance of sunlight and self-restraint due to the COVID-19 pandemic may contribute to reduced vitamin D status. This study provides comparable data on vitamin D status in Japanese young women and assesses the effect of lifestyle, including changes caused by the COVID-19 pandemic, on vitamin D status. In study 1, 39 young healthy Japanese women aged 21–25 y were recruited from May 2016–June 2017. Serum 25-hydroxyvitamin D (25OHD) concentration and diet and lifestyle information were obtained from participants each month (n=124). In study 2, using the same parameters as study 1, young women aged 21–23 y (n=10) were recruited in September 2020. In the results of study 1, we found the frequencies of vitamin D deficiency (25OHD<20 ng/mL) in spring, summer, fall, and winter were 90.5%, 62.5%, 81.5%, and 91.3%, respectively. The substantial difference of serum 25OHD concentration was obtained in spring (Δ3.6 ng/mL) and summer (Δ5.1 ng/mL) depending on the frequency of sunscreen use (0–2 d/wk, 3–7 d/wk). In study 2, serum 25OHD concentration in September 2020 was extremely lower than in September 2016 (13.2 ng/mL vs. 21.7 ng/mL). The number of days spent outside in 2020 decreased drastically compared with 2019. In conclusion, vitamin D deficiency was highly common in Japanese women in their early 20s, and frequent sunscreen use contributed to low vitamin D status. Moreover, because the decrease in days outside due to the COVID-19 pandemic obviously resulted in a decline in vitamin D status, both appropriate sunbathing and increased dietary vitamin D intake are recommended to young women.

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© 2022 by the Center for Academic Publications Japan
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