Scientists are exploring the complex relationship between the trillions of bacteria in our gut and our food preferences. While known for their role in digestion and immunity, emerging research suggests gut microbes might even manipulate our cravings.
Early theories proposed that gut microbes could generate cravings for specific foods or induce discomfort to encourage hosts to eat what benefits them. For instance, the bacterium Salmonella Typhimurium has been observed to hijack gut-brain chemical signals to maintain host feeding even during infection.
A 2022 study transplanted microbiomes from wild rodents with varied diets into germ-free mice. Researchers found that different microbiomes led to significantly different food choices, with herbivore microbiomes favoring protein and carnivore microbiomes favoring carbohydrates.
Gut bacteria can produce neurotransmitters like serotonin, which plays a role in appetite regulation. Approximately 90% of the body's serotonin is produced in the gut, with bacteria directly influencing this production. The study observed that mice with herbivore microbiomes had higher levels of tryptophan, a building block of serotonin, potentially suppressing carbohydrate cravings.
This suggests a feedback loop: our microbiome shapes cravings, and our diet shapes our microbiome. While human food choices are complex, influenced by culture and learned behaviors, recent research has begun to bridge this gap. A 2025 study in Nature Microbiology identified Bacteroides vulgatus, a gut bacterium that can suppress sugar cravings by producing a metabolite that triggers GLP-1, a hormone targeted by drugs like Ozempic. People with type 2 diabetes showed lower levels of this bacterium.
While microbes may not solely drive our choices, they can influence low-grade feelings about food and our internal nutritional state.