Your microflora can make a huge difference to how you respond to diet

Gut flora matters a lot to how your respond to different diets.  A study that was published this month in Cell Host & Microbe, researchers investigate why mice that switch from an unrestricted American diet to a healthy, calorie-restricted, plant-based diet don’t have an immediate response to their new program. Their find was  that certain human gut bacteria need to be lost for a diet plan to be successful.

“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,” says Jeffrey Gordon, Director of the Center for Genome Sciences and Systems Biology at Washington University in St. Louis and main author of the paper. “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.”

The study

In order to find out how human dietary decisions influence the human gut microflora and how the microbes accustomed with one dietary lifestyle responds to a new prescribed diet, Gordon and his team 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 scientists found that people who followed the restricted, plant-rich diet had a more varied gut flora.

After this they colonized groups of germ-free mice with the different human donors’ gut microbes and fed the animals the donor’s native diet or the other diet type.  Both groups of mice responded to their new diets, but the mice with the American diet-conditioned microflora had a smaller response to the plant-rich diet.

To find out microbes that could improve the response of the American diet-conditioned gut flora, the researchers set up a series of staged encounters between mice. Animals who had American diet-conditioned human gut flora lived with mice colonized with microbes from different people who had consumed the plant-rich diet for a pretty long time. Microbes from the plant diet-accustomed communities made their way into the American diet-conditioned microflora, 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 the  co-author Nicholas Griffin. “Many of these bacteria that migrated into the American diet-conditioned microbiota were initially absent in many people consuming this non-restricted diet.”

The researchers

are optimistic that their approach will help steer the development of new methods for improving the effectiveness of prescribing healthy diets, they say that more research is needed to pinpoint the factors that govern the exchange of microbes between people.

“We have an increasing appreciation for how nutritional value and the effects of diets are impacted by a consumer’s microbiota,” says Gordon. “We hope that microbes identified using approaches such as those described in this study may one day be used as next-generation probiotics. Our microbes provide another way of underscoring how we humans are connected we are  to one another as members of a larger community.”

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