Gluten-free and casein-free (GFCF) diets, also known as “autism diets,” have been heralded as reliable treatment options for Autism Spectrum Disorder (AUS) by some therapists, but scientific evidence has been lacking. A recent study published in the Journal of the Academy of Nutrition and Dietetics has found that using dietary supplementation to treat children with autism is not only ineffective, but it could also lead to both insufficient nutrients and excessive nutrients.

"Many families try a GFCF diet in an attempt to improve symptoms of ASD," Dr. Patricia A. Stewart, assistant professor of Pediatrics at the University of Rochester Medical Center, said in a statement. "While 19 percent of all Autism Speaks Autism Treatment Network (AS ATN) participants were reported to be on a GFCF diet, 12 percent of the children in the subgroup participating in this study were given a GFCF diet and were significantly more likely to use nutritional supplements (78 percent vs. 53 percent). However, the micronutrient intake of children on or off the diet was remarkably similar."

Stewart and her colleagues recruited 368 children between the ages of 2 and 11 who had been diagnosed with autistic disorder, Asperger's disorder, or pervasive developmental disorder, according to the DSM-5. Researchers tasked caregivers with three-day food records that tracked all foods, beverages, and nutritional supplements, which included brand names, recipes, and photos of labels.

Children affected by AUS ended up consuming similar amounts of micronutrients as healthy children with AUS and had the same deficits in vitamins D, E, calcium, potassium, and choline. Fifty-six percent of children with AUS are given supplements compared to around 35 percent of the general population. Following supplementation, between 40 and 55 percent of children with AUS were still lacking calcium while between 30 and 40 percent were lacking vitamin D.

"In clinical practice, each patient needs to be individually assessed for potential nutritional deficiencies or excess,” Stewart added. “Few children with ASD need most of the micronutrients they are commonly given as multivitamins, which often leads to excess intake that may place children at risk for adverse effects. When supplements are used, careful attention should be given to adequacy of vitamin D and calcium intake.”

Although children with autism generally lacked a sufficient amount of calcium and vitamin D, dietary supplementation often led to excessive nutrient consumption. Many children with AUS who received dietary supplementation exceeded "tolerable upper limit" for safe intake levels of vitamin A, folic acid, and zinc.

Source: Hyman S, Schmidt B, Stewart P, et al. Dietary Supplementation in Children with Autism Spectrum Disorders: Common, Insufficient and Excessive. Journal of the Academy of Nutrition and Dietetics. 2015.