Obesity and Vitamin D Insufficiency among Adolescent Girls and Young Adult Women from Korea.

Although there is evidence of the biological mechanisms by which obesity may induce vitamin D insufficiency or deficiency, limited epidemiological studies have been conducted, especially among Asian adolescent girls and young adult women who are at a high risk of vitamin D deficiency. This study aimed to examine the cross-sectional association between obesity and vitamin D insufficiency among adolescent girls and young adult women in Korea. We used data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2014, and 3623 girls and young adult women aged 12-29 years were included. Demographic and lifestyle data were collected using a self-administered questionnaire from the health interview survey. Serum 25-hydroxyvitamin D (25(OH)D) level, body mass index (BMI), and body fat percentage (BF%) were measured during health examinations. Multivariable logistic regression was used considering the complex, multistage probability sample design of KNHANES. In the multivariable-adjusted analyses, obese girls and women, defined by BMI, were more likely to have a higher prevalence of vitamin D insufficiency (odds ratio [OR]: 1.49, 95% confidence interval [CI]: 1.03-2.17). This association was also evident for BF%. Participants with ≥30% BF% had a significantly higher prevalence of vitamin D insufficiency (OR: 1.52, 95% CI: 1.07-2.16). Obesity may worsen vitamin D insufficiency among adolescents and young women because of the fat-soluble characteristics of vitamin D and related health behaviors, such as a lack of outdoor activity. Further large-scale prospective cohort studies or randomized controlled trials are warranted to confirm this causality.