A casein-free diet is an eating plan in which milk protein (casein) is eliminated by removing all dairy products and all foods containing casein from the diet. It is often, if not always, used in combination with a gluten-free diet, which calls for the elimination of wheat, barley, rye, oats, and any products made from these grains. Both diets are called elimination diets because a particular type of food is virtually eliminated from the child's meals (1).
Proponents of the casein-free diet say that many children with autism have gastrointestinal difficulties that make it hard for them to digest milk protein properly. There are different possibilities for ways in which this could affect children with autism. The most studied theory is that eating or drinking milk protein leads to high levels of protein by-products, called casomorphines, in some children with autism. These by-products may then affect behavior like a drug would. Specifically, in these children, casomorphines could reduce their desire for social interaction, block pain messages, and increase confusion. If milk protein is taken out of the diet, the idea is that this will reduce the level of casomorphines, and behavior will improve as a result (2-4).
Parents who choose a casein-free diet for their child must become aware of the ingredients of everything in their grocery cart. Products that contain milk or milk proteins include butter, cheese, yogurt, cream, ice cream, PediasureTM, casein, or caseinate. Foods containing milk or casein in any form should not be purchased. Read labels carefully, because milk or mild products can be present in surprising places, like soy yogurt or sausages. Maintaining a milk-free diet can be hard at first because milk or casein are present in many prepared foods. However, parents can take a casein-free cooking class or read a casein-free cookbook (see Resources) to learn how to cook without milk protein and still provide enough nutrition for the child (see Is it harmful?).
Casein is broken down in the intestines into several by-products, including one called casomorphine. 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 casomorphine is being absorbed into the general circulation in children with autism, then it could affect behavior (2-5).
In support of this theory, injection of casomorphine in animals activates areas of the brain that have been reported to be involved in autism (6). Moreover, there is evidence that blocking at least some of the action of casomorphine improves the behavior of children with autism (7). Finally, recent evidence of a genetic mutation common among children with autism has been traced to a gene involved in gastrointestinal function (8).
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 (9). 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 (10). 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 (10). 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. In a third study that did examine the effectiveness of a casein-free diet alone, children with autism were tested for food allergies and pre-selected for sensitivity to milk. Any other foods to which the children were allergic were also removed from the diet for 8 weeks, and significant behavior improvements resulted (11).
The current thinking is that there is at least some evidence showing that a casein-free diet, when combined with a gluten-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 in the current scientific literature to support or refute this intervention. Scientists have concluded that there are currently not enough published studies to draw a meaningful conclusion (3, 4).
The major health concern for a child on a casein-free diet is whether the child receives adequate nutrition. A recent report showed that the protein and nutrient intakes of children with autism on gluten- and casein-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 (12). As a result, some researchers suggest that all children on elimination diets should be under the care of a nutritionist or physician (1). Also, look for calcium-enriched rice milk, soy milk, and orange juice for easy sources of calcium.
A casein-free diet can be expensive and challenging to do, particularly because our culture uses dairy products often. As casein-free diets become more common, the price and availability of casein-free options are becoming less of an issue. Typically, casein-free foods and milk substitutes have been stocked by specialty, health-food, and organic grocery stores that often have higher price tags. However, some milk-free products such as soy and rice milk are becoming more readily available in mainstream grocery stores. Also, adapting your diet to include more dairy-free recipes is possible without an increase in your grocery bill. For example, use olive or canola oils instead of butter, or make dishes and simply omit the cheese, like tacos garnished with avocado instead of cheese can work well.
Most restaurants offer casein-free meals, though limited menu choices may be available, and special preparation may be requested (i.e. salad with no cheese), depending on the restaurant. Notify your server of your needs so they can help to make sure there are no milk products in the foods you order.
Online sources for casein-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 casein-free items.
Cookbooks as well as gluten- and casein-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 casein-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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