Do the microbes in your gut influence what foods you like?
Scientists have identified more than 3,000 species of bacteria living in the human intestine. We know they play a role in digestion and immune function. But can they also influence the types of food we crave?
In a 2014 study in the journal BioEssays, researchers proposed that gut microbes might manipulate their hosts’ eating behavior by generating cravings for foods the bacteria thrive on, or even causing discomfort until the host eats what benefits them.
SUBSCRIBE TO OUR NEWSLETTER
Sign up for our weekly Life’s Little Mysteries newsletter to hear about the latest mysteries before they appear online.
Salmonella Typhimurium is an example. He hijacks chemical signals between the gut and brain so that its host continues to eat during infection.
“In general, when you have gastro [gastrointestinal] infection, you stop eating,” Alcock said. “And Salmonella [Typhimurium] actually seems to harm that…so the animals continue to eat and produce infectious particles in their feces which then infect other animals.
However, this was a theoretical paper: it proposed mechanisms by which microbes might manipulate food cravings, but did not demonstrate that this was the case. The proposed pathways – including altering taste receptors and hijacking the vagus nerve – were plausible, but not confirmed, particularly in the context of daily cravings.
How the microbiome can influence food choices
In 2022, researchers tested this hypothesis. In their study, Kevin Kohlassociate professor of biology who focuses on the impact of interactions with microbes on the physiology, ecology and evolution of animal hosts at the University of Pittsburgh, and Brian Trevellinemicrobiologist and postdoctoral researcher at Cornell University, transplanted microbiomes from wild rodents with different diets—carnivore, herbivore, and omnivore—into germ-free mice, then measured what they ate.
“Maybe I naively thought that the carnivore-inoculated mice were going to eat a high-protein diet,” Kohl told Live Science. “That’s not what we saw.”
Instead, mice with herbivorous microbiomes preferred protein, while mice with carnivorous microbiomes preferred carbohydrates. But a key discovery occurred: different microbiomes led to very different food choices.
But how? Gut bacteria can produce many of the same neurotransmitters that the brain uses to regulate appetite, including serotoninwhich signals the brain when you have eaten enough. In fact, almost 90% of the body’s serotonin is produced in the gutnot in the brain, and research has shown that gut bacteria play a direct role in this production.
I could definitely see feedback cycles where changes in the microbiome perpetuate behaviors or cause different cravings.
Kevin Kohl, associate professor of biology at the University of Pittsburgh
In the mouse study, the team found that mice given the herbivorous microbiome had significantly more tryptophan – a building block of serotonin – in their blood. Previous research showed that higher levels of serotonin suppress carbohydrate cravings in particular, which may explain why these mice opted for a high-protein diet.
“This could be at least one potential pathway in which the microbiome affects diet, appetite and food preferences,” Trevelline said.
The results also raise the possibility that the relationship is bidirectional. If your microbiome shapes your cravings and your diet shapes your microbiome, small changes in what you eat could change the cycle over time.
“I could totally see feedback cycles where changes in the microbiome perpetuate behaviors or cause different cravings,” Kohl said.
However, Kohl and Trevelline’s study involved mice. “Food choice is really tricky and totally different in humans,” Kohl said. “It is influenced by culture, society, economics, learned behaviors, associations.” In other words, many other factors affect our food choices.
Yet a recent research article has begun to connect these findings to human health. In a 2025 study published in the journal Natural microbiologyresearchers discovered that an intestinal bacteria 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 like Ozempic. People with type 2 diabetes also had lower levels of this bacteria, the researchers found.
But Kohl cautioned against giving your microbes too much credit for your choices. “Free will still exists,” he said. “Microbes don’t determine our choices. But these cravings, these low-level feelings about food – those come from our internal nutritional state” – things like amino acids and other compounds circulating in the body – “which we know are influenced by the microbiome.”
