Consuming high-dose dietary prebiotics may affect the reward signals in the brain and associated food decision-making, potentially opening the door for less invasive obesity treatments, a study finds.
"The results suggest a potential link between gut health and brain function, in this case, food decision-making," says Veronica Witte, co-author of the study and a scientist at the University of Leipzig Medical Center.
Prebiotics are non-digestible food ingredients, usually carbohydrates, that support gut health by promoting the growth and activity of friendly bacteria in the gut. They are found in plant-derived foods such as onions, leeks, artichokes, wheat, bananas, and in high concentrations in chicory root. Many people also take prebiotic supplements.
The study published in the journal Gut included 59 adults aged 18 to 42 with a body mass index (BMI) between 25 and 30, which falls within the overweight range. They 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 wanted to eat the meals depicted. After the MRI experiment, they were provided with their highest-rated dish and asked to eat it.
The participants underwent MRI examination four times: 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.
Prebiotics for weight loss
When the participants evaluated high-calorie foods, there was comparatively less activation of reward-related brain areas after they had consumed the prebiotic fiber. Moreover, the use of prebiotics was linked to altered composition of the gut bacteria. The findings suggest that functional microbial changes may change brain response towards high-calorie food cues, ultimately aiding in obtaining a healthy weight.
The study, however, has several limitations, including its duration — 14 days of intervention may be considered too short to induce long-lasting effects on neuronal processes involved in eating behavior. Additionally, secondary analyses did not replicate the exact same activation clusters at the whole brain level.
Moreover, the findings should be generalized with caution because the study did not recruit representative shares of female and diverse genders.
What are the benefits of prebiotics?
Some studies – but not all – suggest that prebiotics may be beneficial for those with irritable bowel syndrome (IBS), which causes chronic abdominal pain and altered bowel habits without any organic cause. For instance, two recent clinical trials have shown that the symptoms of IBS improved after consuming 5 g/day of fructooligosaccharides for 6 weeks or 3.5 g/day of galactooligosaccharides for 12 weeks.
Meanwhile, the health benefits of prebiotics' effect on Crohn's disease, an inflammatory bowel disease, remain conflicting.
Clinical trials showed that prebiotics from fermentation products, such as butyrate, and symbiotic therapy of Lactobacillus rhamnosus, Bifidobacterium Lactis, and inulin, could reduce the risk of colorectal cancer, the third leading cause of cancer-related deaths in the United States.
Research also suggests that prebiotics can improve immunity by increasing the population of protective microorganisms and decreasing the population of harmful bacteria.
The new study indicates that prebiotic intake plays a role in weight loss, as it can potentially be used as a dietary intervention to treat unhealthy eating behaviors or overnutrition. However, more research is needed to expand on the beneficial effects.
- Gut. Prebiotic diet changes neural correlates of food decision-making in overweight adults: a randomised controlled within-subject cross-over trial.
- The University of Leipzig Medical Center. How Plant Derived Nutrients Can Affect the Gut and Brain.
- National Library of Medicine. Prebiotics: Definition, Types, Sources, Mechanisms, and Clinical Applications.
- Centers for Disease Control and Prevention. Probiotics and Prebiotics: Where Are We Going?