Scientists suspect that your gut microbiome – the mix of bacteria that inhabit your intestines – affects your health in many ways, but a surprising new finding suggests that a healthy microbiome may even ease the symptoms of autism.
The small study of 18 children with autism who also had severe digestive problems found that a faecal transplant to rebalance their gut microbiome reduced both their digestive symptoms and their autism symptoms. The improvements persisted during the two-year study follow-up period.
"We treated children with autism by altering the gut microbiota. All had gastrointestinal symptoms – diarrhoea, constipation, stomach pain – and those symptoms were reduced dramatically, and their behaviour improved as well," said study senior author Rosa Krajmalnik-Brown. She's a professor at the Biodesign Institute at Arizona State University in Tempe, Arizona.
"When we checked again two years later, behaviour was even better and gastrointestinal symptoms were still much better, but not as good as right after treatment," she said.
Krajmalnik-Brown said it's not clear exactly how improving the microbiome helps autism symptoms. Because all of the children had severe digestive issues, she said it's possible that "they may be more comfortable and better able to focus and learn", she suggested.
It also might be that healthier microorganisms in the gut may send chemicals to the brain that help children learn and make connections, she added.
The researchers noted that 30% to 50% of people with autism also have chronic digestive problems that may make them irritable and make it difficult to learn, pay attention and behave well.
The kids treated in the study were found to have a low diversity of bacteria in their intestines at the beginning of the study. All 18 received the faecal transplant daily for seven to eight weeks.
Decrease in autism symptoms
The treatment increased the diversity of microbes and healthy bacteria in the gut, according to the researchers.
When the study started, 83% of the children were classified as having severe autism. At the end of the study, only 17% were severe, 39% were mild or moderate, and 44% were below the cut-off for mild autism spectrum disorder, the findings showed.
A professional evaluation of the children's symptoms found a 45% decrease in autism symptoms compared to the start of the study.
Many of the study participants had multiple factors that could lead to a less diverse microbiome. For example, many were born by Caesarean section, which is linked to fewer gut bacteria. Other factors were reduced breastfeeding, increased use of antibiotics and low fibre intake, the researchers said.
Dr Andrew Adesman, chief of developmental and behavioural paediatrics at Cohen Children's Medical Center in New Hyde Park, New York, reviewed the study findings.
He said, "Although parents of children with autism frequently note that their children have significant gastrointestinal problems, this study suggests that changing the bacteria in the gut may lead to sustained improvements in a child's autism symptoms."
A more diverse diet
However, Adesman said it's important to remember that the study didn't have a placebo group, and all the children and parents knew they were receiving the treatment.
In addition, he noted that only children with autism and severe digestive problems were included in the study. It's not clear if this treatment would be helpful for kids with autism who don't have digestive problems.
Both Adesman and Krajmalnik-Brown agreed that more study of this treatment is needed.
Krajmalnik-Brown said that parents who are interested in improving their child's microbiome can try feeding them a more diverse diet, including more fibre from foods such as vegetables and fruits.
She stressed that no one should attempt the study treatment at home. "This was done in very supervised conditions. Done incorrectly, it could cause gastrointestinal infections," Krajmalnik-Brown said.
The findings were published online in the journal Scientific Reports.
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