Researchers say mounting evidence points to the role of gut abnormalities in autism.
Scientists in China and the US led a review of more than 150 papers on the gut.
Dr Randi Hagerman: she says there are important relationships between the gut, the immune system and autism
Gut problems are a common comorbidity in people with autism, say the researchers.
The studies they reviewed suggest that anywhere between 23 per cent and 85 per cent of children with autism have gastrointestinal difficulties.
Bacteria link to improvements
The researchers say many recent studies have shown treatments regulating bacteria in the intestines have resulted in improvements in autism.
Behind the theory linking the gut to autism is the idea that an overgrowth of bad bacteria results in toxins. The suggestion is that these bacteria weaken the lining of the intestines and reach the brain.
Treatments for gut abnormalities
The researchers looked at treatments to restore a healthy gut. Probiotics, prebiotics, faecal transplants, specialised diets and antibiotics were among these treatments.
Probiotics are live bacteria and yeasts. In contrast, prebiotics are ‘non‐living’ food ingredients that ‘feed’ probiotics and thereby help them flourish.
The researchers say probiotic treatments have a proven ability to normalise intestinal symptoms. As for prebiotics, they say the available evidence for their effectiveness is lacking.
Faecal transplants are highly effective for treating Clostridium difficile infections. One of the main symptoms of a Clostridium difficile infection is diarrhoea.
But the researchers raise the issue of the safety of faecal transplants. Abdominal cramps, belching, and low-grade fever are among possible side-effects of transplants.
Paediatrician Dr Randi Hagerman, of the University of California, Davis, was one of the researchers involved in the review.
In an email, Hagerman said they were not recommending faecal transplants. However, she said “there are important relationships between the gut, the immune system and ASD and even other chronic diseases”.
Gluten-free, casein-free diet may help gut abnormalities
The researchers also point to studies suggesting a gluten-free and casein-free diet can help.
Overall, they say “well-designed research studies with more participants are needed to provide more evidence”.
The paper was published in Frontiers in Cellular Neuroscience.
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Published: 26 June 2017
