According to a recent study published in the Public Library of Sciences ONE journal, autistic children who are fed soy formula had 2.6 times as many febrile seizures as those children fed non-soy formula. About 25 percent of infant formula sold in the United States is soy formula, the most popular non-dairy formula option.

The researchers began their study by investigating a drug for its potential to reduce seizures in an animal model. To simplify the study, the researchers used a purified feed. They noticed a difference between mice fed the standard feed, which was soy based, and the purified feed which was a dairy-derived formula.

“We were intrigued that a dietary alteration was as effective as many medicines in reducing seizure incidence and wanted to pursue that finding,” said Cara Westmark, PhD. “We found that the main difference between the diets was the protein source. The standard diet was soy-based, while the purified diet was casein, or dairy, based.”

From there, they analyzed data from a sample of almost 2,000 children and found the link between soy-based formula and increased seizures. “This is not saying that all autistic children who eat soy-based formula are going to develop seizures,” Westmark was careful to say. But the increase is worrying, she noted.

More studies will be needed to determine if the link is actually causal. That is, does the soy formula cause the increase in seizures, or is there another factor involved? “This needs to be studied more thoroughly. If soy formula is lowering the threshold for seizures or increasing the incidence of seizures, we need to know that.” Indeed. I’ll keep you posted as I learn more.