Autism and Digestive Issues

Guest post by Alessio Fasano, MD, professor of pediatrics, medicine and physiology and director of the Mucosal Biology Research Center and the Center for Celiac Research, at the University of Maryland School of Medicine. Dr. Fasano is conducting Autism Speaks-funded research on GI issues and autism.

If my child has autism-related GI issues, will this affect his ability to absorb nutrients from multivitamins and other supplements?

A child’s ability to absorb nutrients from food or supplements really depends on the type of gastrointestinal (GI) problem that the child has. GI issues are very common in children with autism, but the problems can range from constipation to irregular bowel movements to acid reflux to stomach aches to malabsorption to food revulsions. Some of these issues have little effect on a child’s nutritional status or his ability to absorb nutrients, whether from food or supplements. Other GI disorders can have a real impact.

Related issues that can affect a child’s nutritional status include lactose intolerance, being on a gluten-free or casein-free diet and being a picky eater. These restrictions increase a child’s chance of being deficient in certain nutrients such as vitamin D and calcium. However, they don’t reduce a child’s ability to absorb nutritional supplements, which can help overcome dietary deficiencies.

GI problems that can affect nutrient absorption – from diet or supplements – include celiac disease and intolerance to casein, or milk protein. These can decrease the body’s ability to absorb nutrients and supplements.

Yet another GI problem common in children with autism is diarrhea caused by food moving too quickly through the intestines. This faster passage through the digestive tract can hamper nutrient absorption. To compensate, a physician may recommend supplements. But if the diarrhea is related to irritable bowel syndrome – which involves abnormal intestinal function, not sped up digestion – poor absorption is less likely. 

Recent research has suggested a new, and still controversial, theory that abnormal changes in the gut’s digestive bacteria may cause GI problems in some children with autism. This “proximal bowel contamination” theory suggests that bacteria that belong in the bowel move up into the small intestine, where they don’t belong. If this proves to be true, these bacteria would, in essence, be stealing nutrients from the body. In theory, this could result in nutrient deficiencies. At this time, we don’t have enough evidence to support this claim, though study continues. Meanwhile, many labs offer diagnostic “dysbiosis” tests to detect these bacteria. I’m not a fan because the results don’t provide any practical guidance for treatment.

In general, nutrients in food are easier to absorb than nutrients from vitamin and mineral supplements. This is because nutrients in food generally come in a more absorbable form.

If a child with autism has a normal appetite, diet and growth rate, my recommendation for supplements is the same for any other child. In general, supplements are appropriate during the first year of life but are not strictly necessary thereafter. If a child is on a special diet or has growth issues, then speak to your pediatrician about nutritional supplements.