Is there a connection between gut bacteria and autism? It’s a question that has sparked considerable debate, with many claims circulating about the role of gut health in autism symptoms. But what does the science really say? A major scientific review, published on November 15, 2025, in the journal Neuron, dives deep into these claims, offering some surprising insights.
For years, there’s been a perceived link between autism and gut bacteria. This has led to a surge in supplements and specialized diets designed to target gut bacteria, with the promise of reducing autism symptoms. However, experts have often expressed skepticism. This review set out to examine the evidence, focusing on the three main pillars supporting the gut-brain-autism connection: clinical trials, observational studies, and experiments on mice.
But here’s where it gets controversial… The review found significant flaws and inconsistencies in the existing research.
One of the key areas of investigation was the diversity of gut bacteria in autistic individuals. Some studies suggested that autistic children have more diverse gut bacteria than others. However, other studies presented contradictory findings, indicating less diversity. Still others found no significant difference.
These conflicting results have been used to support the idea that the microbiome plays a role in autism, which the researchers found problematic. They pointed out that the inconsistencies might be due to small sample sizes and the vastness of the data. When studies were conducted with larger samples, the review found that autism accounted for only 3% to 5% of the variation in the microbiome. This suggests that gut bacteria may not be as significant a factor as some claim.
And this is the part most people miss… The review also examined the impact of diet on autism. One study looked at the dietary habits of autistic children and found that they often have a narrower range of food choices. However, instead of finding that diet caused autism or was caused by gut bacteria, the experts concluded the opposite. They suggested that the dietary differences were a result of behavioral changes associated with autism.
Despite the lack of solid evidence, the link between gut bacteria and autism persists. The researchers attribute this to what they call “pseudo-triangulation,” where seemingly independent sources of evidence appear to converge but fall apart under closer scrutiny.
As the lead author, Kevin Mitchell, a developmental neurobiologist, stated, “Despite what you’ve heard, read, or watched on Netflix, there is no evidence that the microbiome causally contributes to autism.” He emphasized that autism is a strongly genetic condition and that more research should focus on this aspect.
What do you think? Do you believe the current research adequately addresses the relationship between gut bacteria and autism? Are there other factors you think are more important? Share your thoughts in the comments below!