Autism and Food Allergies

Father having food with son at dining table in house
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Autism is a disorder that affects brain development in children. This disease causes problems with social interaction and communication skills, and limitations in behavior patterns. Autism is likely genetic, although there also seems to be environmental factors that influence the disease.

Do Food Allergies Cause or Worsen Autism?

In recent years, various studies -- mostly in the alternative medicine literature -- have suggested that food allergies play a role in causing or worsening autism.

Specifically, gluten (a wheat protein) and casein (a milk protein) have been blamed for worsening symptoms in children with autism. These food proteins are felt to be broken down into smaller proteins (peptides) that function like narcotics in children with autism, thereby worsening the behavioral changes of autism.

Many other foods are blamed for worsening autism as well, including eggs, tomatoes, eggplant, avocado, red peppers, soy, and corn. However, authors of alternative medicine literature on the subject of autism and food allergies admit that allergy tests to these foods, as well as to wheat and milk, are usually negative, and most of these children do not seem to experience typical symptoms of food allergies. Therefore, they recommend testing for specific antibodies (IgG) against these foods. However, a set of guidelines known as the Practice Parameters for Allergy Diagnostic Testing states that IgG antibodies have no role in the diagnosis of food allergies.

Diets free from the above foods, mostly gluten-free and casein-free diets, have been studied for children with autism. Most of these studies are of very poor quality and not up to modern-day scientific standards. One Cochrane analysis on this subject found only one small, well-designed study that showed some improvement in autistic traits in the children receiving a gluten-free/casein-free diet.

Studies of larger numbers of children are needed to confirm the results of this small study.

How Could Foods Worsen Autism?

It’s not completely clear that foods do worsen autism, although there are many theories about how this could occur. It's been suggested that autism could result from a loss of regulation of the immune system, causing an increase in inflammatory-causing chemical signals from white blood cells. It is felt that these chemicals (cytokines) may be responsible for the neurological abnormalities seen in children with autism.

Recent studies suggest that children with autism may respond to certain foods, particularly gluten- and casein-containing foods, by producing more of these inflammatory cytokines. Blood cells from autistic children were cultured with various foods in a lab, and various inflammatory cytokines were measured. The cytokines from the autistic children were much higher than those from normal (non-autistic) children after being exposed to gluten or casein. This increase may help predict when an autistic child would benefit from dietary avoidance of these proteins.

Are Women with Allergies at Risk for having Children with Autism?

It has also been suggested that the immune system changes a pregnant woman experiences could place her child at risk for autism.

Many reports of women with various autoimmune diseases, such as type 1 diabetes, are at increased risk for having children with autism.

A recent study assessed the relationship between autoimmune diseases and autism. It found that only psoriasis predisposes a woman to having a child with autism. However, the study also showed that having allergic rhinitis and/or asthma, particularly when diagnosed during pregnancy, places a woman at increased risk of having a child with autism.

Again, the reason for this is not completely clear; however, most theories involve changes to the immune system during pregnancy and the production of these inflammatory chemicals.

These cytokines may somehow contribute to symptoms of autism in genetically predisposed children.

Should My Autistic Child Avoid Eating Gluten and Casein?

At the present time, there does not appear to be enough information to support following a gluten-free/casein-free diet for children with autism. Furthermore, limiting a child’s dietary intake, especially by avoiding nutritionally important foods such as milk and wheat, may be dangerous. Be sure to contact your child’s physicians before limiting his or her diet in any way.

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Croen LA, Grether JK, Yoshida CK, et al. Maternal Autoimmune Diseases, Asthma and Allergies, and Childhood Autism Spectrum Disorders. Arch Pediatr Adolesc Med. 2005; 159:151-7.

Millward C, Ferriter M, Calver S, Connell-Jones G. Gluten- and casein-free diets for autistic spectrum disorder. Cochrane Database of Systematic Reviews 2004, Issue 2. Art. No.: CD003498.

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