PHILADELPHIA — "You are what you eat" is familiar enough, but how deep do the  implications go? An interdisciplinary group of investigators from the Perelman School of Medicine at the University of Pennsylvania have found an association between long-term dietary patterns and the bacteria of the human gut.  In a study of 98 healthy volunteers, the gut bacteria separated into two distinct groups, called enterotypes, that were associated with long-term consumption of either a typical Western diet rich in meat and fat versus a more agrarian diet rich in plant material.  A subsequent controlled-feeding study of 10 subjects showed that gut microbiome composition changed detectably within 24 hours of initiating a high fat/low fiber or low fat/high fiber diet, but that the enterotype identity of the microbe group remained stable during the 10-day study, emphasizing the short-term stability of the enterotypes. The findings were published this week in Science Express, and may have implications for exploring the relationship between diet and therapies for gastrointestinal disorders.

“It’s well known that diet strongly affects human health, but how diet influences health is not fully understood,” says Frederic D. Bushman, PhD, professor of Microbiology , who led the study together with co-principle investigators James Lewis, MD, MSCE, professor of Medicine in the Division of Gastroenterology and professor of Epidemiology, and Gary Wu, MD, professor of Medicine in the Division of Gastroenterology.  “We found that diet is linked to the types of microbes in the gut, which provides a potential mechanism connecting diet with health.”

Wu noted, “Although the mechanisms by which diet influences gut microbes remain to be fully characterized, our findings also provide insights into the differences in the types of gut bacteria observed in various societies across the globe.”

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