A gluten-free diet is an eating plan in which gluten (a protein found in some grains) is eliminated from the diet. Foods and drinks containing wheat, barley, rye, oats, or anything made from these grains are avoided. A gluten-free diet is often used for children with autism in combination with a casein-free diet. The casein-free diet calls for the elimination of milk protein (casein). Both diets are called elimination diets because a particular type of food is eliminated from the child's meals and snacks (1).
Proponents of the gluten-free diet say that many children with autism have gastrointestinal difficulties that make it hard for them to digest certain grains properly. There are different possibilities for ways in which this could affect children with autism. The most studied theory is that eating gluten leads to high levels of protein by-products, called gluteomorphines, in some children with autism. These by-products may then affect behavior like a drug would. Specifically, in these children, gluteomorphines could reduce their desire for social interaction, block pain messages, and increase confusion. If gluten is taken out of the diet, the idea is that this will reduce the level of gluteomorphines, and behavior will improve as a result. (2-4).
Parents who choose a gluten-free diet for their child must become aware of the ingredients of everything in their grocery cart. Products containing wheat, barley, rye, or oats in any form should not be purchased. Foods containing modified food starch also contain gluten, but modified corn starch does not. Maintaining a gluten-free diet can be hard to do at first because gluten is present in many prepared foods. However, parents can take a gluten-free cooking class or read a gluten-free cookbook (see Resources) to learn how to cook without gluten and still provide enough nutrition for the child (see Is it harmful?).
Gluten is broken down in the intestines into several by-products, including one called gluteomorphine. These by-products are much more common in the urine of children with autism than in children without autism. Some scientists have concluded that they are leaking from the intestines into the blood of these children (2, 5). Many research studies report that children with autism often have gastrointestinal problems, including intestinal leakage (5). The argument is that, if gluteomorphine is being absorbed into the general circulation in children with autism, then it could affect behavior (2-5).
In support of this theory, there is evidence that blocking at least some of the action of gluteomorphine improves the behavior of children with autism (6). Moreover, recent evidence of a genetic mutation common among children with autism has been traced to a gene involved in gastrointestinal function (7).
The effectiveness of elimination diets in improving the behavior of children with autism has only recently been scientifically researched. This research has almost always examined diets that are both casein- and gluten-free.
One well-controlled study focused on children with autism who had abnormally high protein by-products in their urine, and therefore were more likely to be sensitive to casein and gluten (see What is the theory behind it?). One group of these children was fed a strict casein- and gluten-free diet for 12 months. This group had significantly fewer autistic symptoms than the remaining children, who were not fed this diet (8). Another well-controlled study of casein- and gluten-free diets focused on children with autism regardless of the level of protein by-products in their urine (9). Overall, the study found no significant differences in behavior between children on the elimination diet and children on regular diets, although individual parents reported behavioral improvements (9). This overall lack of effect in the second study could be because the elimination diet only lasted 6 weeks, or because the children were not pre-selected according to the level of protein by-products in their urine.
Regardless, in both cases, the tested diets were casein- and gluten-free, so it is not clear whether it was the elimination of casein, gluten, or both that resulted in any improvements. A third study that did examine the effect of a gluten-free diet on the behavior of children with autism did not compare children on the elimination diet with children not on the diet (10). Therefore, even though there were improvements seen in the behavior of children on the diet, these may also have occurred over the 5 months of the study without the elimination diet.
The current thinking is that there is at least some evidence showing that a gluten-free diet, when combined with a casein-free diet, can help improve the behavior of some children with autism. Although the casein-free diet combined with a gluten-free diet is popular, there is little evidence to support or refute this intervention and reviewers have determined that meaningful conclusions cannot be drawn from the existing literature (3, 4).
The major health concern for a child on a gluten-free diet is whether the child receives adequate nutrition. A recent report showed that the protein and nutrient intakes of children with autism on casein- and gluten-free diets were not different from those of children with autism on standard diets, but there was a trend towards lower calcium and copper intake in children on elimination diets (11). As a result, some researchers suggest that all children on elimination diets should be under the care of a nutritionist or physician (1).
A gluten-free diet can be expensive and difficult to follow, but as these diets become more common, the transition to the new diet becomes easier. Gluten-free versions of many favorite foods such as pasta, bread, and cookies are becoming more readily available in mainstream stores. Moreover, changes in the diet to replace breads, pastas, and other processed foods with vegetables, protein, and other whole foods are big steps toward a healthy, gluten-free diet.
Restaurants offering exclusively gluten-free meals are likely to be on the pricey side and are not common. Most restaurants will have gluten-free options on their menu (i.e. salads without croûtons, fish or meat with vegetables served without bread or breading, etc.), although these choices may be limited. You may need to notify your server that you need gluten-free food choices, and they can help you choose between the available options or suggest changes to menu items.
Online sources for gluten-free cooking ingredients are also available, and some of these may be priced more affordably (see Resources ). Also, bulk or co-op buying may ease the cost of gluten-free items.
Cookbooks as well as casein- and gluten-free diet starter kits for children with autism can be found at: http://www.gfcfdiet.com/.
The Food Allergy and Anaphylaxis Network provides many resources to help children live with a gluten-free diet: http://www.foodallergy.org/.
Several books that might be helpful in understanding the casein-free diet approach are:
Diet Intervention and Autism: Implementing a Gluten Free and Casein Free Diet for Autistic Children and Adults: A Guide for Parents by Marilyn Le Breton and Rosemary Kessick. 2001. Jessica Kingsley Publishers.
How to Eat Well Again on a Wheat, Gluten and Dairy-Free Diet by F. Crosthwaite. 2006. Merton Books.
Special Diets for Special People: Understanding and Implementing a Gluten-Free and Casein-Free Diet to Aid in the Treatment of Autism and Related Developmental Disorders by Lisa S Lewis 2005. Future Horizons.
The Kid-Friendly ADHD and Autism Cookbook: The Ultimate Guide to the Gluten-Free, Casein-Free Diet by P. Compart and D. Laake. 2006. Fair Winds Press.
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