According to Gram Research analysis, both fecal microbiota transplantation and ketogenic diet significantly improved autism symptoms in a 2026 study of 30 children. The ketogenic diet group showed stronger behavioral improvements, with symptom scores dropping by about 20 points, while both treatments reduced autism severity by 1-2 points. Each treatment changed gut bacteria differently, suggesting multiple pathways to improvement.
A new study compared two different approaches to help children with autism by changing their gut bacteria. Researchers looked at 30 children who received either a fecal microbiota transplant (FMT)—where healthy bacteria from a donor are transferred to the child’s digestive system—or followed a ketogenic diet (a high-fat, low-carb eating plan). Both treatments helped reduce autism symptoms like difficulty with social interaction and repetitive behaviors. The study found that each treatment changed the gut bacteria in different ways, suggesting that improving digestive health might be one way to help with autism symptoms.
Key Statistics
A 2026 study of 30 children with autism found that the ketogenic diet reduced behavioral symptom scores from 63.07 to 42.73, a reduction of approximately 32%, compared to baseline measurements.
In the same 2026 research of 30 autistic children, fecal microbiota transplantation significantly increased butyrate-producing bacteria (Wujia chipingensis, Eubacterium sp. MSJ-33, and Butyrivibrio crossotus) while the ketogenic diet enriched propionate metabolism pathways with a fold enrichment of 3.747.
Both treatment groups in a 2026 study of 30 children with autism showed statistically significant improvements in autism severity scores (CARS), declining by approximately 1-2 points from baseline measurements of around 35 points.
The Quick Take
- What they studied: Whether two different gut-health treatments—a fecal microbiota transplant and a ketogenic diet—could reduce autism symptoms in children and how each treatment changed their gut bacteria.
- Who participated: 30 children diagnosed with autism spectrum disorder (ASD) according to standard diagnostic criteria. The children were split into two groups: one receiving FMT treatment and one following a ketogenic diet.
- Key finding: Both treatments significantly improved core autism symptoms. The ketogenic diet group showed stronger improvements in behavioral symptoms (ABC scores dropped from 63.07 to 42.73), while both groups showed similar improvements in autism severity (CARS scores decreased by about 1-2 points). Each treatment changed the gut bacteria differently.
- What it means for you: If your child has autism and digestive problems, these results suggest that improving gut health through either FMT or a ketogenic diet might help reduce some autism symptoms. However, this is early research with a small group, so talk to your doctor before trying either approach. Results take time and aren’t guaranteed for every child.
The Research Details
Researchers recruited 30 children with autism and divided them into two groups. One group received a fecal microbiota transplant (FMT), a procedure where healthy bacteria from a donor are introduced into the child’s digestive system to restore a healthier bacterial balance. The other group followed a ketogenic diet, which is very high in fats and very low in carbohydrates.
Before and after the treatments, researchers measured how severe each child’s autism symptoms were using two standard tests: the CARS (Childhood Autism Rating Scale) and the ABC (Aberrant Behavior Checklist). They also collected stool samples and used advanced DNA sequencing to identify exactly which bacteria were living in each child’s gut before and after treatment.
This approach allowed researchers to see whether the treatments worked and, if they did, whether they worked by changing the gut bacteria in similar or different ways.
Many children with autism also have digestive problems and unusual gut bacteria. Scientists have noticed that the gut bacteria might be connected to autism symptoms through something called the gut-brain axis—basically, the bacteria in your digestive system can send signals to your brain. By studying whether treatments that change gut bacteria also improve autism symptoms, researchers can understand whether fixing the gut might help the brain.
This study is relatively small (30 children) and published in 2026, so it’s recent research. The researchers used rigorous methods to diagnose autism and measure symptoms, and they used advanced DNA sequencing to identify bacteria. However, the small sample size means results should be considered preliminary. The study didn’t include a control group that received no treatment, which would have made it stronger. Both groups did improve, but we can’t be completely sure whether the improvements were due to the treatments or other factors.
What the Results Show
Both treatment groups showed meaningful improvements in autism symptoms. In the FMT group, autism severity scores (CARS) dropped from 34.87 to 33.53, a statistically significant decrease. The ketogenic diet group also showed significant improvement, with CARS scores declining from 35.13 to 33.
Behavioral symptoms showed even stronger improvements, especially in the ketogenic diet group. Children in the KD group had ABC scores drop from 63.07 to 42.73—a reduction of about 20 points, which is substantial. The FMT group also improved but less dramatically (from 79.93 to 69.33).
Interestingly, the two treatments changed the gut bacteria in distinctly different ways. The FMT treatment increased bacteria that produce butyrate, a short-chain fatty acid that’s beneficial for gut health. The ketogenic diet, meanwhile, increased bacteria involved in propionate metabolism and the breakdown of aromatic compounds. These different bacterial changes suggest that both treatments might help autism symptoms through different biological pathways.
The study found that overall bacterial diversity (how many different types of bacteria were present) didn’t change significantly in either group. This was surprising because researchers often expect diversity to increase with treatment. However, the specific types of bacteria that were present did change meaningfully, suggesting that the quality and function of the bacteria matter more than just the quantity of different species. The ketogenic diet showed particularly strong enrichment of propionate metabolism pathways, which may be important for brain function.
Previous research has suggested that gut bacteria changes might be linked to autism symptoms, but few studies have directly compared different treatments that target the gut. This study adds to growing evidence that both FMT and ketogenic diets can improve autism symptoms, though it’s one of the first to show they work through different bacterial mechanisms. The findings align with earlier research showing that children with autism often have different gut bacteria than typically developing children.
The study had several important limitations. First, it was very small—only 30 children total—so results might not apply to all children with autism. Second, there was no control group that received no treatment, so we can’t be completely certain the improvements were due to the treatments rather than other factors like natural improvement over time or placebo effects. Third, the study didn’t follow children long-term to see whether improvements lasted. Finally, the study didn’t measure how the bacterial changes actually connected to symptom improvements in individual children, so we can’t be sure the bacteria changes caused the symptom improvements.
The Bottom Line
Based on this early research, neither FMT nor ketogenic diet can be recommended as standard autism treatment yet. However, if your child has autism and significant digestive problems, discussing these approaches with your pediatrician or gastroenterologist may be worthwhile. The ketogenic diet showed slightly stronger behavioral improvements but requires significant dietary changes. FMT is a medical procedure with its own risks and benefits. Both approaches need more research in larger groups before they can be considered proven treatments. Confidence level: Low to Moderate (early-stage research).
Parents of children with autism who also have digestive problems should pay attention to this research. Children with autism who have constipation, diarrhea, or other GI issues might benefit most. However, children with autism who don’t have digestive problems may not benefit as much. Anyone considering these treatments should work closely with their medical team. This research is NOT yet strong enough to recommend these treatments to all children with autism.
Based on the study, improvements in autism symptoms appeared within the timeframe of the treatment (the exact duration isn’t specified in the abstract). However, changes to gut bacteria and their effects on the brain typically take weeks to months to develop. Don’t expect overnight improvements. If trying either approach, plan to give it at least 8-12 weeks before evaluating whether it’s helping.
Frequently Asked Questions
Can fecal microbiota transplantation help reduce autism symptoms?
A 2026 study of 30 children found that FMT significantly improved autism severity scores and increased beneficial butyrate-producing bacteria. However, this is early research with a small group, so more studies are needed before FMT can be recommended as a standard autism treatment.
Does the ketogenic diet help children with autism?
A 2026 study showed the ketogenic diet produced stronger behavioral improvements than FMT, with symptom scores dropping by about 32%. However, the diet requires significant lifestyle changes and should only be attempted under medical supervision.
How do these gut treatments help autism symptoms?
Both treatments change gut bacteria in different ways. FMT increases butyrate-producing bacteria while the ketogenic diet enriches propionate metabolism. These bacterial changes may communicate with the brain through the gut-brain axis, potentially reducing autism symptoms.
Should I try these treatments for my child’s autism?
Talk to your child’s doctor first. These are early-stage treatments with limited evidence. They may be worth considering if your child has both autism and significant digestive problems, but they’re not yet proven standard treatments for all children with autism.
How long does it take to see improvements from these treatments?
The study didn’t specify exact timelines, but gut bacteria changes typically take weeks to months to affect symptoms. Plan to give either treatment at least 8-12 weeks before deciding if it’s working for your child.
Want to Apply This Research?
- Track specific autism-related behaviors weekly: social interactions initiated, repetitive behaviors observed, and any digestive symptoms (constipation, diarrhea, stomach pain). Use a simple 1-10 scale for each category to see if they improve over time with treatment.
- If following a ketogenic diet, log daily meals and snacks to ensure adherence to the high-fat, low-carb requirements. If pursuing FMT, track post-procedure symptoms and any changes in digestion. Both approaches require consistency, so daily logging helps ensure you’re following the plan correctly.
- Set monthly check-ins to review trends in symptom tracking. Compare scores from month to month to see if improvements are continuing, plateauing, or reversing. Share this data with your child’s doctor to make informed decisions about continuing or adjusting treatment.
This research is preliminary and based on a small study of 30 children. Neither fecal microbiota transplantation nor ketogenic diet is currently an approved or standard treatment for autism. These approaches carry potential risks and should only be pursued under close medical supervision. Parents should consult with their child’s pediatrician, neurologist, or gastroenterologist before attempting either treatment. This article is for informational purposes only and should not replace professional medical advice. Individual results vary, and what works for one child may not work for another.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.