The Dietary Science Foundation
Telephone:+46 70-750 22 16
269 39 Båstad
The hypothesis that gluten and milk affect autism has existed for several decades, but has never received any proper attention. There is also a comorbidity between epilepsy and autism. For epilepsy, a strict low carbohydrate diet has been proven to have an effect, but no large studies have ever examined whether this kind of diet might also help in autism. The Dietary Science Foundation wants to evaluate both of these connections between diet and autism.
The theory that the cereal protein gluten and milk protein casein might affect autism has a long history. The scientific literature is full of small studies that examine the connections, but results point in different directions. The theory recognizes the fact that children with autism relatively often have gastrointestinal problems. This seems to apply to a subgroup of children. In a survey from 2013, parents of thousands of children with an autism spectrum diagnosis answered questions about constipation, diarrhea and flatulence. Gastrointestinal problems were found to be eight times more common in children with autism compared with children who developed normally. In 2012, in a study of 14,000 children with an autism spectrum diagnosis, medical records showed gastrointestinal problems to be 2.6 times more common. Several more studies have indicated that around 40 percent of all children with autism have trouble with their bowels. There are also a great number of studies that show that the children’s intestinal flora is disturbed.
Some researchers believe that a disturbed bowel leads the intestines to leak, allowing pieces of milk and gluten proteins to enter the bloodstream. When they reach the brain, they can, according to this theory, serve as opium-like substances (opioids) that interfere with signals between nerve cells.
This theory is controversial in the scientific community. But new research shows that people with autism are more likely to have an immune system that reacts to gluten. A Swedish study from 2013 showed that gluten-related antibodies in the blood were four times as common. Two similar studies were published the same year with the same results. In one study, milk protein antibodies were also seen to be more common in people with autism.
When researchers have previously studied whether a gluten and dairy-free diet can help in autism, all the children with autism were put in the same group. In these studies, it seemed like some children were helped by the diet, while others noticed no effect at all. There is a need for high-quality studies in which only children carrying antibodies to gluten and milk proteins are included.
Another question that needs an answer is whether the diet that helps a subgroup of children with epilepsy can also help with autism. Children with epilepsy are often helped by an extremely strict form of low-carbohydrate diet called a ketogenic diet. Around one-third of all children with autism also have epilepsy (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3031934/). The more severe the autism a child has, the greater the risk that epilepsy will also develop. When researchers look for genetic changes that are associated with severe epilepsy, they also find a large overlap with the autism spectrum. Just as with epilepsy, the cellular power plants, the mitochondria, are often dysfunctional in autism. This does not apply to all autistic children, but to many of them. The more debilitated the mitochondria are, the greater the degree of autism that may develop. Just as with epilepsy, there are high levels of free radicals inside the cells, and levels of a protective substance called glutathione is low.
Because there are so many similarities between the two diseases, Greek researchers tested a ketogenic diet as a treatment for autism early in the 2000s. On the island of Crete, an unusually high number of children are diagnosed with autism. Thirty children tried a strict low-carbohydrate high-fat diet and twenty-three of them managed to stick to it. Five of the twenty-three saw no effect and stopped the diet after a short time. Of the eighteen remaining children, all were improved. Two boys were so much better that they could start attending a regular school, eight of the children had a moderate improvement, and eight more saw a small improvement. In total, a quarter of the children made a large enough improvement that it was worth it to follow the strict diet; among other things it became easier for them to concentrate and learn.
When the results were published, the Greek researchers wrote that the topic required further exploration. But so far no similar studies have been conducted. In 2013, researchers reported that a ketogenic diet works for autism-like behaviors in mice. There is a need for scientific studies that evaluate whether a subgroup of children with autism can be helped by a strict low-carbohydrate diet. Autism is a disability that is on the increase among children and it’s important to find effective treatments.
There is a rare form of celiac disease called gluten ataxia where patients have gluten-related antibodies in their blood. People with ataxia lose their motor skills. Some are no longer able to walk and need wheelchairs. The reason is that the immune system attacks and destroys part of the cerebellum.
A large registry study from Sweden shows an association between celiac disease and epilepsy; epilepsy is 40 percent more common among people who have gluten intolerance. Nobody knows yet why these connections exist.