Serum 25-hydroxyvitamin d concentrations and season-specific correlates in Japanese adults

• Published in: Journal of epidemiology Vol. 21; no. 5; pp. 346 - 353
• Main Authors: Nanri, Akiko, Foo, Leng Huat, Nakamura, Kazutoshi, Hori, Ai, Poudel-Tandukar, Kalpana, Matsushita, Yumi, Mizoue, Tetsuya
• Format: Journal Article
• Language: English
• Published: Japan Japan Epidemiological Association 2011
• Subjects: Adult; Aged; Correlation analysis; Employment - statistics & numerical data; Female; Humans; Japan; Life Style; Male; Middle Aged; Nutrition; Occupational Health Services; Original; Risk Factors; Seasons; Vitamin D; Vitamin D - analogs & derivatives; Vitamin D - blood; Vitamin D Deficiency - diagnosis; Young Adult; Japan
• ISSN: 0917-5040; 1349-9092
• DOI: 10.2188/jea.je20100161

Several lines of evidence indicate an important role for vitamin D in the prevention of a range of diseases. Blood vitamin D levels show clear seasonal variation; however, data on the determinants of vitamin D status for each season are limited. We investigated the association between lifestyle and serum vitamin D concentration by season in Japanese workers. Subjects were 312 men and 217 women aged 21 to 67 years who worked in municipal offices in Northern Kyushu, Japan and participated in a periodic checkup in July or November. Multiple linear regression analysis was used to examine the association between serum 25-hydroxivitamin D concentrations and lifestyle factors for each season. Mean serum 25-hydroxyvitamin D concentration was 27.4 ng/ml (68.4 nmol/L) and 21.4 ng/ml (53.4 nmol/L) for workers surveyed in July and November, respectively (P < 0.001); the prevalence of vitamin D deficiency (<20 ng/ml) was 9.3% and 46.7%, respectively (P < 0.001). In November, dietary vitamin D intake (in both sexes) and nonsmoking and physical activity (in men) were significantly associated with higher concentrations of serum 25-hydroxyvitamin D. In summer, fish/shellfish intake was associated with higher serum 25-hydroxyvitamin D concentrations in women. Vitamin D deficiency is common in Japanese workers during seasons with limited sunlight. The lifestyle correlates of favorable vitamin D status in November were physical activity, dietary vitamin D intake, and nonsmoking.