Prevalence of vitamin D deficiency among overweight and obese US children

Adequate vitamin D is essential for skeletal health in developing children. Although excess body weight is associated with risk of vitamin D deficiency, the national prevalence of and risk factors associated with vitamin D deficiency in overweight and obese children are unknown.

The prevalence of vitamin D deficiency (defined as 25-hydroxyvitamin-D <20 ng/mL) was determined in a sample of 6- to 18-year-old children who were enrolled in a cross-sectional study (the 2003-2006 National Health and Nutrition Examination Survey) in which body weight and height were measured directly. Children were classified as healthy-weight, overweight, obese, or severely obese by using recommended age- and gender-specific BMI-percentile cut points. Associations between BMI-percentile classification and vitamin D deficiency were examined after adjustment for relevant confounders. Sample weights were used to generate nationally representative estimates.

The prevalence of vitamin D deficiency in healthy-weight, overweight, obese, and severely obese children was 21% (20%-22%), 29% (27%-31%), 34% (32%-36%), and 49% (45%-53%), respectively. The prevalence of vitamin D deficiency in severely obese white, Latino, and African-American children was 27% (3%-51%), 52% (36%-68%), and 87% (81%-93%), respectively. Compared with healthy-weight children, overweight, obese, and severely obese children had significantly greater adjusted odds of vitamin D deficiency. Modifiable factors associated with vitamin D deficiency in overweight/obese children were identified.

Vitamin D deficiency is highly prevalent in overweight and obese children. The particularly high prevalence in severely obese and minority children suggests that targeted screening and treatment guidance is needed.