Adiposity predicts vitamin D status of children

A negative association between serum 25‐hydroxyvitamin D [25(OH)D] concentrations, regarded as the accepted marker of vitamin D status, and adiposity has been found in adults. However, whether a similar relationship exists in children remains unclear. Using a nationally representative sample of children age 6 – 18 years from the National Health and Nutrition Examination Survey 2005‐2006 (n=2838), we compared serum 25(OH)D levels with measures of adiposity (weight, waist circumference (WC), WC to height ratio (WCHt), body mass index (BMI), skin fold thickness, and % body fat). Based on serum 25(OH)D concentrations, 10.5 ± 1.5% of the children were vitamin D deficient (< 15 ng/mL) and 63 ± 2.2% were vitamin D insufficient (15‐29 ng/mL). Controlling for age, gender, ethnicity, and poverty income ratio, markers of adiposity were strongly related to 25(OH)D levels by linear regression analysis: weight (P=0.026), WC (P=0.016), WCHt (P=0.015), BMI (P= 0.017) and triceps skin fold thickness (P= 0.021). A subgroup analysis (n=2086; 8‐18 years) of % body fat measured by dual energy X‐ray absorptiometry was especially strongly related to serum 25(OH)D levels (P< 0.0001). Possible explanations may include sequestration of vitamin D by excess body fat or modulation of adipogenesis through vitamin D receptor‐dependent pathways. In conclusion, low 25(OH)D concentrations are associated with increased adiposity and are common among children .