Does the gut flora in your stomach affect your food preferences?

Could the microorganisms in your gut sway your food desires?

Over 3,000 bacterial species have been identified residing in the human gut. We are aware of their function in digestion and immune system operations. However, could they also affect the types of foods we yearn for?

A 2014 research article in the journal BioEssays proposed that gut microorganisms might manipulate the eating patterns of their hosts by creating desires for foods that benefit the bacteria, or by inducing discomfort until the host consumes what is advantageous for them.

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

(Image credit: Marilyn Perkins / Future)

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An instance of this is Salmonella Typhimurium, which manipulates the chemical signals exchanged between the gut and the brain to sustain its host’s eating habits during an infection.

“Typically, when you have a GI [gastrointestinal] infection, you stop eating,” Alcock stated. “And Salmonella [Typhimurium] seems to actually impair that … so that animals continue to eat and continue to produce infectious particles in their poop that go on to infect other animals.”

Nevertheless, this was a speculative publication – it suggested ways that microbes could influence cravings but had not confirmed this. The mechanisms it put forth—such as modifying taste receptors and exploiting the vagus nerve—were believable but unverified, particularly concerning regular food cravings.

How the microbiome may influence food choices

In 2022, scientists investigated this notion. In their investigation, Kevin Kohl, an associate professor of biology at the University of Pittsburgh whose research focuses on how interactions with microbes affect the physiology, ecology, and evolution of animal hosts, along with Brian Trevelline, a microbiologist and postdoctoral fellow at Cornell University, transferred microbiomes from wild rodents with diverse diets—carnivorous, herbivorous, and omnivorous—into germ-free mice, and subsequently assessed their food consumption.

“I perhaps naively thought that the carnivore-inoculated mice were going to eat the high-protein diet,” Kohl shared with Live Science. “That’s not what we saw.”

Conversely, the mice harboring herbivore microbiomes showed a preference for protein, whereas those with carnivore microbiomes favored carbohydrates. However, a crucial outcome remained: distinct microbiomes resulted in significantly altered dietary selections.

But how? Gut bacteria have the capability to produce many of the same neurotransmitters that the brain utilizes to regulate appetite, including serotonin, which signals satiety to the brain. In fact, approximately 90% of the body’s serotonin is generated in the gut, not the brain, and research indicates that gut bacteria play a direct part in this synthesis.

I could totally see some feedback cycles where shifts in the microbiome either perpetuate behaviors or bring about different cravings

Kevin Kohl, associate professor of biology at the University of Pittsburgh

Within the mouse study, the researchers observed substantially higher levels of tryptophan—a precursor to serotonin—in the blood of mice that received the herbivore microbiome. Prior research has established that elevated serotonin levels tend to curb carbohydrate cravings specifically, which might account for the shift towards a high-protein diet in those mice.

“That might be at least one potential avenue in which the microbiome is affecting diet, appetite and dietary preferences,” Trevelline commented.

The findings also suggest the possibility that the relationship is bidirectional. If your microbiome influences your cravings, and your diet influences your microbiome, minor adjustments in your food intake could potentially alter the cycle over time.

“I could totally see some feedback cycles where shifts in the microbiome either perpetuate behaviors or bring about different cravings,” Kohl remarked.

However, the study conducted by Kohl and Trevelline involved mice. “Food choice is really tricky and totally different in humans,” Kohl noted. “It’s influenced by culture, society, economics, learned behaviors, associations.” In other words, numerous other elements impact our dietary decisions.

Nonetheless, a recent research paper has begun to link these discoveries to human well-being. In a 2025 study published in the journal Nature Microbiology, scientists discovered that a gut bacterium known as Bacteroides vulgatus can diminish sugar cravings in mice by generating a metabolite that stimulates the production of glucagon-like peptide-1 (GLP-1), the same hormone targeted by medications such as Ozempic. The researchers also found that individuals with type 2 diabetes had diminished levels of this bacterium.

However, Kohl advised against attributing too much influence to your microbes concerning your choices. “Free will still exists,” he asserted. “The microbes are not driving our choices. But these cravings, low-grade feelings about food—those come from our internal nutritional state”—referring to elements like amino acids and other compounds circulating in the body—”which we know is influenced by the microbiome.”

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