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Microbiome bioactives may trigger food cravings

Article-Microbiome bioactives may trigger food cravings

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New research suggests the gut microbiome can influence food selection, potentially by mediating the availability of essential amino acids.

While individuals make food choices every day, anyone who has craved a salad over a steak knows at times those choices seem to be driven by forces outside of the brain. In fact, a new animal study out of the University of Pittsburgh suggests gut bacteria may impact food cravings and choices (PNAS. DOI: 10.1073/pnas.2117537119).

In a study with germ-free mice, colonized with different microbiomes from wild rodents with different feeding strategies, researchers found the type of gut bacteria impacted feeding preferences. Colonized mice different in voluntary carbohydrate selection, and feeding preferences were connected to differences in circulating amino acids, bacterial tryptophan metabolism, and intestinal morphology.

Specifically, herbivore-conventionalized mice voluntarily selected a higher protein:carbohydrate diet; omnivore- and carnivore-conventionalized mice selected a lower protein:carbohydrate diet. The research team, led by Kevin Kohl, also noted the findings supported a hypothesis that the essential amino acid tryptophan—a precursor of serotonin—functions as a peripheral signal regulating diet selection. The bacterial genes involved in tryptophan metabolism and plasma tryptophan availability prior to the selection trial were significantly correlated with voluntary carb intake.

“There are likely dozens of signals that are influencing feeding behavior on a day-to-day basis,” said Brian Trevelline, a post-doc who worked on the trial with Kohl, in a statement. “Tryptophan produced by microbes could be just one aspect of that.”

Finally, the herbivore-conventionalized mice had larger intestinal compartments associated with microbial fermentation, reflecting the intestinal morphology of the donor species. Collectively, the findings offer a new insight into how the gut microbiota influences dietary choices, with the potential to explore how the microbes impact dietary choices along with other factors.