The bacteria living in and on you may subtly be influencing your behavior, writes Carl Zimmer in his Matter column at the New York Times.
A recent essay by a trio of researchers from New Mexico and California appearing in BioEssays explores the idea that microbe in your gut may influence the foods you crave. "From the microbe's perspective, what we eat is a matter of life and death," the University of California, San Francisco's Carlo Maley tells Zimmer. And they may need their host — you — to eat something that increases their fitness even though it decreases yours.
Theories about food cravings, Zimmer says, either suggest that they are a way to replenish and store nutrients that had been missing or liken them to addictions. However he notes that chocolate, a commonly craved food, is neither an essential nutrient nor something that you need to eat more of to get the same satisfaction, indicating that those theories are flawed and something else may be at play. Microbes, Maley says, may fill that gap.
Rob Knight from the University of Colorado, who was not one of the essay authors, tells Zimmer that it is an interesting notion. He adds that if it's true, that people may be able to, in turn, manipulate what bacteria are present in their gut, replacing them with one that would make them crave healthier foods.
"It would obviously be of tremendous practical importance," Knight says, though he warns that research in to the link between the microbiome and behavior is still early days.