https://www.pitt.edu/pittwire/features-articles/food-cravings-pitt-study Skip to main content University of Pittsburgh Pitt Wire Explore Sections * open search * open menu Close From the latest big breakthrough to the most influential and inspiring figures on campus to Pitt in the community, Pittwire is your official source for what's happening now. Explore By Topics * Health and Wellness * Technology and Science * Arts and Humanities * Community Impact * Diversity, Equity, and Inclusion * Global * Innovation and Research * Our City/Our Campus Explore By Category * Features & Articles * Accolades & Honors * Ones to Watch * Announcements and Updates Pittwire Other Links * Pitt Magazine * Event Calendar * Social Media Directory Close Search Pitt Search Search for People Close Global Menu * Apply * Visit * Give * Pittwire * Events Navigation Navigation * About * Academics * Admissions * Research * Life at Pitt * Athletics Colleges & Schools Colleges & Schools * Arts & Sciences * Business * Computing & Information * Dental Medicine * Education * Engineering * General Studies * Health & Rehabilitation * Honors College * Law * Medicine * Nursing * Pharmacy * Public & Intl Affairs * Public Health * Social Work Info For Info For * + Alumni + Community + Global + Sustainability * Twitter * Instagram * Facebook * Youtube Close Search Pittwire Search Search www.pitt.edu People grabbing food from table during a feast Features & Articles Got food cravings? What's living in your gut may be responsible April 19, 2022 Tags * Health and Wellness * Kenneth P. Dietrich School of Arts and Sciences * Innovation and Research * Share on Twitter - opens in a new window * Share on Facebook - opens in a new window * Share via Email FPO Tower Subscribe to Pittwire Get the most interesting and important stories from the University of Pittsburgh. Subscribe Eggs or yogurt, veggies or potato chips? We make decisions about what to eat every day, but those choices may not be fully our own. New University of Pittsburgh research on mice shows for the first time that the microbes in animals' guts influence what they choose to eat, making substances that prompt cravings for different kinds of foods. "We all have those urges -- like if you ever you just feel like you need to eat a salad or you really need to eat meat," said Kevin Kohl, an assistant professor in the Department of Biology in the Kenneth P. Dietrich School of Arts and Sciences. "Our work shows that animals with different compositions of gut microbes choose different kinds of diets." Despite decades of speculation by scientists about whether microbes could influence our preferred diets, the idea has never been directly tested in animals bigger than a fruit fly. To explore the question, Kohl and his postdoc Brian Trevelline (A&S '08), now at Cornell University, gave 30 mice that lacked gut microbes a cocktail of microorganisms from three species of wild rodents with very different natural diets. The duo found that mice in each group chose food rich in different nutrients, showing that their microbiome changed their preferred diet. The researchers published their work today in the journal Proceedings of the National Academy of Sciences. While the idea of the microbiome affecting your behavior may sound far-fetched, it's no surprise for scientists. Your gut and your brain are in constant conversation, with certain kinds of molecules acting as go-betweens. These byproducts of digestion signal that you've eaten enough food or maybe that you need certain kinds of nutrients. But microbes in the gut can produce some of those same molecules, potentially hijacking that line of communication and changing the meaning of the message to benefit themselves. One such messenger will be familiar to anyone who's had to take a nap after a turkey dinner: tryptophan. "Tryptophan is an essential amino acid that's common in turkey but is also produced by gut microbes. When it makes its way to the brain, it's transformed into serotonin, which is a signal that's important for feeling satiated after a meal," Trevelline said. "Eventually that gets converted into melatonin, and then you feel sleepy." In their study, Trevelline and Kohl also showed that mice with different microbiomes had different levels of tryptophan in their blood, even before they were given the option to choose different diets -- and those with more of the molecule in their blood also had more bacteria that can produce it in their gut. It's a convincing smoking gun, but tryptophan is just one thread of a complicated web of chemical communication, according to Trevelline. "There are likely dozens of signals that are influencing feeding behavior on a day-to-day basis. Tryptophan produced by microbes could just be one aspect of that," he said. It does, however, establish a plausible way that microscopic organisms could alter what we want to eat -- it's one of just a few rigorous experiments to show such a link between the gut and the brain despite years of theorizing by scientists. There's still more science to do before you should start distrusting your food cravings, though. Along with not having a way to test the idea in humans, the team didn't measure the importance of microbes in determining diet compared to anything else. "It could be that what you've eaten the day before is more important than just the microbes you have," Kohl said. "Humans have way more going on that we ignore in our experiment. But it's an interesting idea to think about." And it's just one behavior that microbes could be tweaking without our knowledge. It's a young field, Kohl points out, and there's still lots to learn. "I'm just constantly amazed at all of the roles we're finding that microbes play in human and animal biology," Kohl said. -- Patrick Monahan Trending Meet the undergraduate 'rock star scientist' named a 2022 Goldwater scholar The Pitt Success Pell Match Program has invested more than $95 million in low-income students Pitt Hillel creates meaningful cultural experiences on campus and beyond Bridge Icon University of Pittsburgh Global Menu * Apply * Visit * Give * Pittwire * Events * About * Academics * Admissions * Research * Life at Pitt * Athletics Quick Links & Resources Quick Links & Resources * Accessibility Statement * Careers * Consumer Info/Achievement * Contact Us * Departments A-Z * Diversity, Equity and Inclusion * Find People * Information Technology * Nondiscrimination and Anti-Harassment Policy * My Pitt Regional Campuses Regional Campuses * Bradford * Greensburg * Johnstown * Titusville Colleges & Schools Colleges & Schools * Arts & Sciences * Business * Computing & Information * Dental Medicine * Education * Engineering * General Studies * Health & Rehabilitation * Honors College * Law * Medicine * Nursing * Pharmacy * Public & Intl Affairs * Public Health * Social Work 4200 Fifth Ave Pittsburgh, PA 15260 United States (412) 624-4141 * Twitter * Instagram * Facebook * Youtube