microbiota and diet
Diet & Nutrition

Your Gut Microbes May “Remember” What You Ate, and Make a New Diet Less Effective

Your microbiota may not be on your side as you try improving your diet this New Year. In a study published December 29 2016 in Cell Host & Microbe, Researchers found that certain human gut bacteria need to be lost for a diet plan to be successful.

A release from the publishers quotes Jeffrey Gordon, Director of the Center for Genome Sciences and Systems Biology at Washington University in St. Louis and senior author of the paper, as saying, “If we are to prescribe a diet to improve someone’s health, it’s important that we understand what microbes help control those beneficial effects. And we’ve found a way to mine the gut microbial communities of different humans to identify the organisms that help promote the effects of a particular diet in ways that might be beneficial.”

In order to study how human dietary practices influence the human gut microbiota and how a microbiota conditioned with one dietary lifestyle responds to a new prescribed diet, Gordon and his collaborators first took fecal samples from people who followed a calorie-restricted, plant-rich diet and samples from people who followed a typical, unrestricted American diet. The researchers found that people who followed the restricted, plant-rich diet had a more diverse microbiota.

They then colonized groups of germ-free mice with the different human donors’ gut communities and fed the animals the donor’s native diet or the other diet type. Although both groups of mice responded to their new diets, mice with the American diet-conditioned microbiota had a weaker response to the plant-rich diet.

To identify microbes that could enhance the response of the American diet-conditioned microbiota, the researchers set up a series of staged encounters between mice. Animals harboring American diet-conditioned human gut communities were sequentially co-housed with mice colonized with microbiota from different people who had consumed the plant-rich diet for long periods of time. Microbes from the plant diet-conditioned communities made their way into the American diet-conditioned microbiota, markedly improving its response to the plant diet.

“We need to think of our gut microbial communities not as isolated islands but as parts of an archipelago where bacteria can move from island to island. We call this archipelago a metacommunity,” says first author Nicholas Griffin, an instructor at WUSTL. “Many of these bacteria that migrated into the American diet-conditioned microbiota were initially absent in many people consuming this non-restricted diet.”

Although the scientists are optimistic that their approach will help guide the development of new strategies for improving the effectiveness of prescribing healthy diets, they emphasize that more research is needed to identify the factors that determine the exchange of microbes between people.