To examine if children use supplements to fill gaps in nutritionally inadequate diets or whether supplements contribute to already adequate or excessive micronutrient intakes from foods.

Data were analyzed for children (2-18 years) from the National Health and Nutrition Examination Survey 2003-2006, a nationally representative, cross-sectional survey (n = 7250). Diet was assessed using two 24-hour recalls, and dietary supplement use was assessed with a 30-day questionnaire.

Prevalence of supplements use was 21% (<2 years) and 42% (2-8 years). Supplement users had higher micronutrient intakes than nonusers. Calcium and vitamin D intakes were low for all children. Inadequate intakes of phosphorus, copper, selenium, folate, and vitamins B-6 and B-12 were minimal from foods alone among 2-8 year olds. However, among 9-18 year olds, a higher prevalence of inadequate intakes of magnesium, phosphorus, and vitamins A, C, and E were observed. Supplement use increased the likelihood of intakes above the upper tolerable intake level for iron, zinc, copper, selenium, folic acid, and vitamins A and C.

Even with the use of supplements, more than a one-third of children failed to meet calcium and vitamin D recommendations. Children 2-8 years old had nutritionally adequate diets regardless of supplement use. However, in children older than 8 years, dietary supplements added micronutrients to diets that would have otherwise been inadequate for magnesium, phosphorus, vitamins A, C, and E. Supplement use contributed to the potential for excess intakes of some nutrients. These findings may have implications for reformulating dietary supplements for children.