Impact of demographic, environmental, and lifestyle factors on vitamin D sufficiency in 9084 Japanese adults

Background: Little is known about correlates of vitamin D status in Asian populations. In this study, we established the prevalence of vitamin D sufficiency in the Murakami region (latitude N38 degrees 13') in Niigata, Japan, and examined demographic, environmental, and lifestyle factors that might be associated with vitamin D sufficiency, with the aim of clarifying the relative contributions of previously described determinants of vitamin D status as well as identifying new determinants in this Japanese population. Methods: This study involved a cross-sectional analysis of baseline data obtained from a cohort study conducted in 2011-2013. Participants were 9084 individuals aged between 40 and 74 years who provided blood samples for the determination of plasma 25-hydroxyvitamin D [25(OH)D] concentrations. Lifestyle information was obtained from 8498 participants, with some missing values regarding different lifestyle factors. Multiple logistic regression analysis was used to obtain odds ratios for vitamin D sufficiency, which was defined as a plasma 25(OH)D concentration >= 75 nmol/L. Results: The prevalence of vitamin D sufficiency (i.e., plasma 25(OH)D concentration >= 75 nmol/L) was 9.1%, and significant associations were observed with male gender (P <0.0001; OR = 2.37, 95% CI: 1.84-3.05), older age (P for trend <0.0001), lower BMI (P for trend <0.0001), higher METs score (P for trend = 0.0138), higher vitamin D intake (P for trend = 0.0467), summer season (P for trend <0.0001), longer duration outdoors (P for trend = 0.0026), no sunscreen use (P = 0.0135; OR = 1.40, 95% CI: 1.07-1.82), higher salmon consumption (P for trend <0.0001), higher alcohol consumption (P for trend <0.0001), and lower coffee consumption (P for trend = 0.0025). Unlike other populations previously reported, vitamin D sufficiency was associated with older age. Conclusions: The prevalence of vitamin D sufficiency (i.e., 25[OH]D >= 75 nmol/L) was low (9.1%) in this Japanese population. A number of demographic, environmental, and lifestyle factors are associated with vitamin D sufficiency, and thus lifestyle modification may present an opportunity to achieve vitamin D sufficiency. (c) 2015 Elsevier Inc. All rights reserved.