Results of the study, which was the most tightly-controlled research on dietary intervention and autism to date, were published in the Journal of Autism and Developmental Disorders earlier this month.
The study, which followed a group of children between the ages of 2.5 and 5.5 over the course of 30 weeks, strictly implemented the gluten-free, casein-free (GFCF) diet with each child. The foods were then reintroduced as double-blind placebo-controlled challenges, while the children’s attention, activity, sleep patterns, and bowel movements were meticulously recorded. No significant changes were found when the children were given snack foods with gluten, casein, a combination of both, or a placebo.
Researchers also ensured that the children were receiving the same level of other behavioral interventions and other treatments, so that any observed changes could be safely attributed to diet. Such controls were not in place in previous diet studies.
“These diets have been very popular for many years as potential treatments for Autism Spectrum Disorder, but we have found no evidence that they are effective,” said Susan Hyman, M.D., chief of the Division of Neurodevelopmental and Behavioral Pediatrics at URMC and the study’s lead author. “We also have concerns that families who try these diets may do so without the support of a dietician. A GFCF diet can meet a child’s nutritional needs, but families may benefit from professional advice regarding provision of adequate calcium and vitamin D, for example.”
Gluten is a compound found in wheat, rye, and barley, while casein is contained in milk. Hyman and her colleagues, including Tristram Smith, Ph.D., professor of Neurodevelopmental and Behavioral Pediatrics, commenced the study to provide an evidence base for families who wanted to know more about the potential effect of dietary intervention.
Participating families began with a four-to-six week phase-in where they implemented a GFCF diet, as well as a behavioral intervention program. For the next 12 weeks, children were given snacks containing gluten, casein, both, or placebo, in a randomized order. Snacks were carefully designed in a medical prep kitchen to look, taste, and feel the same, regardless of ingredients; gluten was disguised in favorite foods like banana bread, brownies, and cookies, while casein was placed in pudding, yogurt, and smoothies.
Distribution was blinded so that no one observing the study — including the child, family, and administering research staff — was aware of which snacks the child was receiving in a given week. By the end of the study, each child had received three of each food challenge, with no challenge leading to statistically significant differences. The children were then followed for an additional 12 weeks.
Hyman cautioned that children with allergies or gastrointestinal disorders might indeed benefit from dietary changes. This study was conducted for children with autism who do not have these co-morbidities, and potential candidates were screened for celiac disease, iron or vitamin D deficiency, and wheat or milk allergy.
The research cohort also ideally would have been larger, said Smith — 22 children were initially enrolled and 14 completed the full 30 weeks — but the study was so exacting that recruitment was a challenge.
“One reason that studies like this haven’t been done in the past is that it requires a tremendous amount of effort to control for all the potentially confounding factors,” said Smith.
The researchers noted that this study was not designed to look at more restrictive diets, and believe that further study on nutrition and autism is vital.
“Though we didn’t find any effectiveness for GFCF diets, there are many potentially positive effects that diet can have on children with autism,” said Hyman. “The link between nutrition and behavior needs to be investigated further so families can make informed decisions.”