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Onions and garlic are rich in prebiotics, which could help improve gut health. Adam Nixon/Stocksy
  • Prebiotics, which are naturally found in plant-based foods, play a pivotal role in nurturing beneficial gut bacteria and supporting overall health.
  • New research suggests that a high dose prebiotic regimen could lead to reduced brain responses to calorie-rich foods.
  • This could open doors to less invasive strategies for obesity prevention and treatment.

A new study led by the University of Leipzig Medical Center is shedding light on the potential link between prebiotics and brain function in the context of obesity.

According to the study, published in the journal Gut, consuming significant amounts of prebiotics in one’s diet is associated with a decrease in the brain’s response to high calorie food cues related to reward.

These findings may imply a possible connection between the health of the gut and the way the brain makes decisions about food.

The study focused on young to middle-aged adults who were overweight and followed a typical Western diet.

The 59 participants were given 30 grams of inulin, a prebiotic found in chicory root, every day for two weeks.

During MRI scans, researchers showed the participants images of food and asked about their level of desire to eat those dishes. After the MRI session, researchers gave the participants the dish they desired the most and asked them to eat it.

The researchers conducted MRI scans four times: first before starting the prebiotic treatment, then after the prebiotic intake, followed by another scan before and after a placebo phase.

During this placebo phase, the researchers gave the participants a substance with the same calorie content but without any prebiotics.

When participants rated high calorie foods, their brain’s reward centers showed reduced activity after they had consumed the prebiotic fiber.

This change in brain response was accompanied by a shift in the types of bacteria present in the gut.

Prebiotics are undigestible fibers or compounds found in plant-based foods that nourish and stimulate the growth of beneficial gut bacteria.

They play a crucial role in maintaining a healthy gut microbiome, which can have positive effects on digestive health, overall well-being, immune function, and nutrient absorption.

These non-digestible fibers can be found in foods like onions, leeks, artichokes, wheat, bananas, and are particularly abundant in chicory root.

They enhance the well-being of the gut by stimulating the growth and function of beneficial gut bacteria.

Kelsey Costa, a registered dietitian and nutrition consultant for Consumer Health Digest, not involved in this research, said, “this study presents compelling preliminary evidence on the influence of prebiotic nutrients on food-related decision-making, shedding light on the powerful microbiome-gut-brain nexus.”

“The intake of high dose prebiotic fiber was found to dampen the brain’s response to high calorie food stimuli, suggesting a potential pathway for weight management,” Costa explained.

High fat, high-sugar foods have been shown to hyperactivate brain reward regions, stimulating a desire for such foods and promoting overeating. This could lead to unhealthy weight gain and potentially contribute to the onset of obesity and related health complications such as diabetes and heart disease.
— Kelsey Costa

Megan Hilbert, a registered dietitian specializing in gut health nutrition from Top Nutrition Coaching, who was also not involved in the study, noted that “this paper adds to the growing body of literature that confirms more about the connection between our brain and the gut known as the gut-brain axis.”

“Animal studies have found that prebiotics and probiotics can alter our cravings, metabolism, and mental well-being, so seeing findings like this in human literature is an important next step in understanding how we can modulate the gut to improve human health,” Hilbert explained.

The results of this study, obtained through advanced brain imaging, examining gut bacteria using next-generation sequencing, and analyzing potential metabolic processes, indicate that changes in gut microbes may be responsible for the differences in how the brain reacts to high calorie food images.

The researchers emphasize the necessity for additional research to explore whether therapies targeting the microbiome could offer less invasive methods for preventing and treating obesity.

By understanding how the microbiome, gut, and brain interact, it may be possible to devise new approaches that encourage healthier eating behaviors in individuals at risk.

Costa noted that “the suppression of such hyperactivation by prebiotic fiber, as suggested by the study, opens up fascinating avenues for future research and potential therapeutic strategies for weight management.”

Feeling full with fiber

“These changes were accompanied by significant shifts in gut microbiota, particularly an increase in short-chain fatty acid-producing bacteria known for their beneficial health effects,” Costa said.

Costa, however, noted that these were “preliminary findings, and larger, more diverse studies are needed to confirm and expand on these results.”

Hilbert pointed out that this research “helps confirm what I’ve seen anecdotally as a dietitian, and that is when people consume a higher fiber diet, they tend to have an easier time saying no to cravings for high sugar/high fat foods.”

“We have also seen causal relationships between high fiber diets and lower caloric intake, so these findings suggest part of the reasoning for this is due to changes in brain activation, which is an exciting finding since previous knowledge centered on the idea that fiber keeps us full solely by dampening Ghrelin (hunger hormone) signals.”
— Megan Hilbert

Currently, researchers are conducting a follow-up study, investigating the impacts of prolonged, high-dose prebiotic usage over six months on eating habits, brain function, and body weight in individuals who are overweight or obese.

Costa said she believed the results were promising for the treatment of obesity.

“As obesity rates continue to rise globally, finding effective and sustainable ways to manage weight is of utmost importance. The findings of this study, while preliminary, offer hope for those struggling with weight management,” she explained.

“[The study] highlights the role of diet, specifically prebiotic fiber intake, in modulating brain function and food-related decision-making. By targeting the gut microbiome through dietary interventions, we may be able to modulate brain function and ultimately make it easier to resist the temptation of high-calorie, ultra-processed foods.”
— Kelsey Costa

Hilbert noted that “this study can help inform public health efforts toward increasing prebiotic fibers in the American diet.”

However, she also noted that she’d like to see if the same results can be achieved by adding more fiber to one’s diet rather than taking it in supplement form.

“While a supplement was used in this particular study, I would like to see a comparison done when participants eat 30g of SCFA-producing fiber in a whole food diet,” Hilbert said.

“Since the findings did not show significant differences in blood glucose regulation, it’d be interesting to see if findings change when more whole foods are incorporated into the participants’ diet,” she added.

“For individuals looking to make changes based on this study, taking an inulin-based powder is something they could chat with their doctor or dietitian about. I would also advise eating more high-fiber foods and focusing on those higher in SCFA-producing prebiotics like bananas, asparagus, wheat products, garlic, leeks, etc.”
— Megan Hilbert