They will recruit over 50 children aged four to 10, who have been clinically diagnosed with autism spectrum disorder, for a six-week RCT
The children will be given either a placebo or the prebiotic galacto-oligosaccharide (GOS), a fermentable carbohydrate found in foods such as beans and lentils.
Parents of the children will complete questionnaires to aid the researchers in measuring changes in the children’s social and mealtime behaviours, as well as sleep habits and gastrointestinal symptoms.
Leading the study is Jacqui Palmer, a paediatric dietitian from the university’s Faculty of Health School of Exercise and Nutrition Sciences.
Speaking to NutraIngredients-Asia, she said: "The prebiotic feeds the gut bacteria and is beneficial to the host, increasing good gut bacteria.
“We chose a GOS that's highly bifidogenic as there's pre-clinical evidence that it can help to reduce anxiety through the actions of Bifidobacteria. There's been a handful of studies on adults, and one on autistic children in the UK.”
Indeed, a 2018 UK study involving 30 autistic children found that those who had been supplemented with GOS and who had excluded specific types of food from their diets displayed a significant reduction in anti-social behaviours.
Palmer said, "What we are looking at with this study is whether supplementation with GOS for six weeks can reduce general and basal anxiety levels and improve the quality of life for autistic children and their families.
"I'll also be looking at their sleep behaviours, social interactions, mealtime behaviours, and gastrointestinal symptoms.”
Acting on the axis
With a growing body of scientific evidence around the gut-brain axis and the effect gut bacteria can have on mood and behaviour, Palmer believes prebiotics could help to reduce autistic children’s inherent anxiety, as well as the problematic behaviours linked to autism spectrum disorder.
These include a reliance on rigidity and routine, difficulty with social interactions, and disturbed sleep patterns.
“We hope this study will enable them to adopt a more open approach in general, instead of having a meltdown when their routine is broken," said Palmer.
This could help the children better manage their everyday activities, which could in turn improve the quality of life for them and their family members.
She also said that in addition to potentially lowering the children’s anxiety levels, prebiotic supplementation may also help to improve their dietary habits.
“As a paediatric dietitian, I see many autistic children with gastrointestinal issues, sleep problems, and very difficult or selective and restrictive diets.”
In her experience, many autistic children do not consume enough fruits, vegetables or grains, and tend to consume excessive amounts of refined carbohydrates. They also may not get the prebiotics they need to maintain good gut bacteria.
This deprives the good gut bacteria of the fibre it needs to thrive, which may in turn cause them to begin to digest the mucous of the body's cell linings, which could then contribute to gastrointestinal symptoms.
She added that fibre was needed for gut motility and intestinal health, and prebiotics to increase good gut bacteria, so they could release neurotransmitters that could act via the gut-brain axis to signal the brain to behave differently.
"Feeding the good bacteria food they like also produces short-chain fatty acids (SCFAs), which serve metabolic functions in the body, such as stimulating neurotransmitters.
"The more diverse and abundant your gut bacteria is, the more likely there will be good health outcomes. Ultimately, we're hoping there will be increased flexibility in their diets and lesser dependence on routine, which is one of the core traits of autism.
“There's also bi-directional communication between the gut and brain, and that's the pathway I'm going down.
“By altering the children’s gut microbiome with a prebiotic, we can perhaps produce some beneficial effects on their behaviours largely due to a reduction in their general anxiety levels."
Parents of the children involved in the study will need to help collect stool and saliva samples, with their families taking part in dietary behavioural therapy sessions.
Palmer said, "We want to see if there's a reduction in their basal cortisol levels, and we’ll also be analysing stool samples, so we're measuring the pre- and post-study difference in microbiota."
She added that while this area of research was relatively new and there was thus limited relevant scientific literature, studies on animals had shown encouraging results, with GOS supplementation leading to reduced anxiety and better moods.