Dietary Supplementation in Children with Autism Spectrum Disorders: Common, Insufficient, and Excessive.

BACKGROUND: Little is known about the effect on dietary adequacy of supplements given to children with autism spectrum disorder (ASD).

OBJECTIVE: This cross-sectional study examines dietary supplement use and micronutrient intake in children with ASD.

DESIGN: Three-day diet/supplement records and use of a gluten/casein-free diet (GFCF) were documented. Estimates of usual intake of micronutrients from food and supplements were compared with the Dietary Reference Intakes.

PARTICIPANTS: Children aged 2 to 11 years (N=288) with ASD from five Autism Treatment Network sites from 2009-2011.

MAIN OUTCOME MEASURES: Percentage of children meeting or exceeding upper limits of micronutrient intake with or without supplements and relative to GFCF diet status.

STATISTICAL ANALYSIS: Micronutrient intake from food and supplements was compared by Spearman rank correlation. Usual intake was estimated by the National Cancer Institute method adjusted for age, sex, supplement use, and GFCF diet. Adequacy of intake was compared between supplement use status and between food and total intake in supplement users relative to Dietary Reference Intakes limits.

RESULTS: Dietary supplements, especially multivitamin/minerals, were used by 56% of children with ASD. The most common micronutrient deficits were not corrected (vitamin D, calcium, potassium, pantothenic acid, and choline) by supplements. Almost one-third of children remained deficient for vitamin D and up to 54% for calcium. Children receiving GFCF diets had similar micronutrient intake but were more likely to use supplements (78% vs 56%; P=0.01). Supplementation led to excess vitamin A, folate, and zinc intake across the sample, vitamin C, and copper among children aged 2 to 3 years, and manganese and copper for children aged 4 to 8 years.

CONCLUSIONS: Few children with ASD need most of the micronutrients they are commonly given as supplements, which often leads to excess intake. Even when supplements are used, careful attention should be given to adequacy of vitamin D and calcium intake.