Serum 25-Hydroxyvitamin D Concentrations and Season-Specific Correlates in Japanese Adults

• Main Authors: Akiko, Nanri, Leng, Huat Foo, Kazutosh, Nakamura, Ai, Hori, Kalpana, Poudel-Tandukar, Yumi, Matsushita, Tetsuya, Mizoue
• Format: Article
• Language: English
• Published: Japan Epidemiological Association 2011
• Subjects: R5-130.5 General works
• Online Access: http://eprints.usm.my/36128/1/Foo_LH_JE-21-346.pdf; http://eprints.usm.my/36128/

Background: 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. Methods: 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. Results: 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. Conclusions: 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.