Do the microbes in your gut influence the foods you like?

Scientists have identified more than 3,000 species of bacteria that live in the human gut. We know they play a role in digestion and immune function. But could they also influence the types of foods we crave?

In a 2014 study published in the journal BioEssays, researchers proposed that gut microbes may manipulate the host’s feeding behavior, causing a craving for the food in which the bacteria thrive or causing discomfort until the host eats something that is beneficial to it.

“We don’t always agree with microbes,” study co-author Dr. Joe Alcock, a professor in the Department of Emergency Medicine at the University of New Mexico, told Live Science.

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Salmonella typhimurium is one example. It hijacks chemical signals between the gut and the brain to ensure that the host continues to eat despite infection.

“Usually when you have a gastrointestinal disease, [gastrointestinal] When they get infected, they stop eating,” Alcock said. [Typhimurium] It actually seems to be impaired…so the animal continues to eat and produce infectious particles in its poop, which then infect other animals. ”

However, this was a theoretical paper, and although it proposed a mechanism by which microorganisms could manipulate desire, it had not been demonstrated that they could actually do so. Pathways proposed by the researchers, such as changes in taste receptors and hijacking of the vagus nerve, were plausible but unconfirmed, especially in the context of daily food cravings.

How the microbiome influences food choices

In 2022, researchers tested this hypothesis. In the study, Kevin Cole, an associate professor of biology at the University of Pittsburgh who focuses on how microbial interactions influence the physiology, ecology, and evolution of animal hosts, and Brian Trevelin, a microbiologist and postdoctoral fellow at Cornell University, transplanted microbiomes from wild rodents with a variety of diets, including carnivores, herbivores, and omnivores, into germ-free mice and measured what the mice ate.

“I naively thought that perhaps the carnivore-vaccinated mice would eat a high-protein diet,” Cole told Live Science. “That’s not what we saw.”

Instead, mice with herbivore microbiomes preferred protein, and mice with carnivore microbiomes preferred carbohydrates. However, an important discovery was made. It turns out that different microbiomes make very different food choices.

But how? Gut bacteria produce many of the same neurotransmitters that the brain uses to regulate appetite, including serotonin, which sends signals to the brain when you’ve had enough. In fact, research shows that about 90% of the body’s serotonin is produced in the gut, not the brain, and that gut bacteria play a direct role in its production.

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In a study of mice, the researchers found that the blood of mice fed the herbivore microbiome had significantly more tryptophan, a component of serotonin. Previous studies have shown that high serotonin levels specifically suppress cravings for carbohydrates, which may explain why the mice transitioned to a high-protein diet.

“This may be at least one potential pathway by which the microbiome influences diet, appetite and dietary preferences,” Trevelin said.

This finding also raises the possibility that the relationship goes both ways. If your microbiome shapes your desires and your diet shapes your microbiome, small changes in what you eat can change your cycle over time.

“We now fully understand the feedback cycle in which changes in the microbiome can perpetuate behaviors or cause different desires,” Cole said.

However, Cole and Trevelin’s research was in mice. “Food choices are very difficult and completely different in humans,” Cole said. “It’s influenced by culture, society, economics, learned behavior, and connections.” In other words, many other factors influence our food choices.

Still, one recent research paper is beginning to connect these findings to human health. In a 2025 study published in Nature Microbiology, researchers discovered that a gut bacterium called Bacteroides vulgatus can suppress sugar cravings in mice by producing a metabolite that triggers the production of glucagon-like peptide-1 (GLP-1), the same hormone targeted by drugs such as Ozempic. Researchers found that levels of this bacteria were also lower in people with type 2 diabetes.

But Cole cautioned against placing too much weight on microbes for his selection. “Free will still exists,” he said. “Microbes don’t drive our choices, but we do know that these cravings and low-grade feelings about food come from the nutritional status of the body, such as amino acids and other compounds circulating in the body, and are influenced by the microbiome.”