Prebiotics are chemicals that aid in the colonisation of beneficial bacteria in the stomach. These indigestible dietary fibres are found in many plant-based foods, including onions, leeks, artichokes, wheat, bananas, and in high amounts in chicory root. They encourage the growth and activity of beneficial gut bacteria, which improves gut health. Researchers are now investigating whether some prebiotics can influence brain function by enhancing communication between the gut flora and the brain.
According to the interventional study headed by the University of Leipzig Medical Centre, high-dose dietary prebiotics reduce reward-related brain activation in response to high-calorie meal stimuli. "The results suggest a potential link between gut health and brain function, in this case, food decision-making," said Dr Veronica Witte, co-author of the study and a scientist at the University of Leipzig Medical Center.
Young to middle-aged adults with overweight were selected for the study who followed an omnivorous, Western diet. The 59 volunteers consumed 30 grams of inulin, a prebiotic from chicory root, daily for 14 days. During functional MRI imaging, participants were shown pictures of food and asked how much they desired to eat the meals depicted. Following the MRI experiment, they were provided with their highest-rated dish and asked to consume it.
The MRI examination was repeated at four time points, before and after the prebiotic administration and before and after a placebo phase in which the participants were given a preparation with identical energy density but without prebiotics. When the participants evaluated high-calorie foods, there was comparatively less activation of reward-related brain areas after they had consumed the prebiotic fibre. This effect was accompanied by a shift in the composition of the gut bacteria.
The findings, derived from advanced neuroimaging, next-generation sequencing of gut bacteria, and combined analyses of potential metabolic pathways, suggested that functional microbial changes may underlie the altered brain response towards high-caloric food cues. Fasting blood samples from the participants underwent analysis for gastrointestinal hormones, glucose, lipids, and inflammatory markers.
In addition, gut microbiota and their metabolites, namely short-chain fatty acids, were measured in stool samples. The research was conducted within the Collaborative Research Centre 1052, Obesity Mechanisms.
"Further studies are needed to investigate whether treatments that alter the microbiome could open up new avenues for less invasive approaches to the prevention and treatment of obesity. A better understanding of the underlying mechanisms between the microbiome, gut, and brain could help to develop new strategies that promote healthier eating habits in people at risk" said Dr Witte.