A widely-available nutritional supplement may be key to treating select cases of autism, according to a new study.

Researchers identified a specific gene mutation responsible for a small number of cases of autism accompanied by epilepsy and intellectual disability. Those with the gene mutation experienced a low level of certain amino acids known as branched chain amino acids or BCAAs.

When scientists gave BCAA supplements to mice that were engineered to have the same gene mutation, the animals showed fewer neurobehavioral problems, researchers reported late last week in the journal Science.

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“It was very surprising to find mutations in a potentially treatable metabolic pathway specific for autism,” said Joseph Gleeson of the University of California, San Diego, the senior author of the study. “What was most exciting was that the potential treatment is obvious and simple: Just give affected patients the naturally occurring amino acids their bodies lack.”

Whether or not the approach will work in people, however, is not yet clear. The form of autism that the supplement may be able to treat was spotted in two families of Middle Eastern descent, but is believed to be extremely rare.

When those with autism stemming from the genetic mutation were given BCAA supplements from a health food store, levels of the amino acids in their bodies normalized and the individuals did not see any side effects. However, researchers have not yet determined if the supplement can impact the individuals’ autism or epilepsy symptoms.