Environmental Factors on Par With Diet in Shaping Gut Microbiota

By Megan Brooks

December 08, 2014

NEW YORK (Reuters Health) - Environmental factors play a key role in shaping the composition of the gut microbiota, independent of diet, hints a comparative metabolomics study of vegans and omnivores.

This may mean that "prebiotics might have different levels of effectiveness depending on your origin/culture of residence," Dr. Gary D. Wu, of the Perelman School of Medicine, University of Pennsylvania, Philadelphia, told Reuters Health.

Studies suggest that diet affects the gut microbiota, which subsequently influences the metabolome - the various metabolites, biochemicals and fats in the body - thereby connecting diet, microbiota and health, Dr. Wu and colleagues note in a report online now in Gut.

But the degree to which diet influences the composition of the gut microbiota is "controversial," they point out. "Murine models and studies comparing the gut microbiota in humans residing in agrarian versus Western societies suggest that the influence is large." But is it?

Dr. Wu and colleagues compared 15 vegans and six omnivores from the same urban US environment to investigate the effect of diet on the gut microbiota and the host metabolome.

The considerable dietary differences between the two groups correlated with large variations in the plasma metabolome, but the effect of the differing diets on the composition of the gut microbiota was "surprisingly modest," Dr. Wu said.

"This suggests that if the significant differences in gut microbiota composition in globally distinct human populations are due to diet, such differences may take several generations to evolve or require very early life exposures. Alternatively, the differences in microbiota composition may be, in part, due to environmental factors independent of diet," the investigators note in their paper.

"I think that it is fair to say that unknown environmental factors associated with residence in various cultures may be just as important (or more so) than diet in shaping the composition of the gut microbiota," Dr. Wu told Reuters Health.

Considering the gut microbiota composition "may be important when developing a 'prebiotic' approach to treat disease and/or maintain health by delivering specific substrates for bacterial conversion into beneficial metabolites," the researchers conclude.

"Such prebiotics may demonstrate varying levels of efficacy in culturally distinct human populations. Integrating information about the composition of the gut microbiome with the delivery of substrates focused on metabolite production should help make possible both improved diets and the 'next-generation' prebiotics, probiotics, synbiotics and dietary supplements for maintaining health and treating disease," they add.

SOURCE: http://bmj.co/1wAulHV

Gut 2014.

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