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Sep 12, 2011

Diet Influences Gut Microbes

The average human body is made up of 10 trillion cells and coexists with approximately 10 times that amount of microbes in the gut alone!  Extending from the old saying “you are what you eat,” it’s probably safe to assume that the microbial life that lives alongside us is also influenced by what we eat.  

A recent study done through University of Pennsylvania School of Medicine demonstrates this.  The study showed a variation in gut flora dependent upon whether people ate a high fat animal protein diet or a higher carbohydrate plant-based diet.  Researchers questioned 98 healthy, non-obese American adults about dietary habits and isolated bacterial DNA present in their stool samples.  Depending on the prevalence of different types of bacterial species found, participants were placed in one of two categories or enterotypes, either Bacteroides or Prevotella.  Those in the Bacteroides group tended to consume more animal proteins and fats, while those in the Prevotella group ate a more plant-based diet.  In a follow-up experiment, 10 participants who fell into the Bacteroides category were fed either a high fat/low fiber diet or low fat/high fiber diet for 10 days.  Changes in diet were found to correspond to changes in the types of gut bacteria present, but not to a large enough extent to shift any participant from the Bacteroides group into the Prevotella group.  This indicates that long-term dietary habits must have a stronger influence on gut microflora than short-term.    

Though this was only a small-scale study looking at a limited number of bacterial types, it provides evidence that food choice plays an important role in the types of microorganisms hanging out in our digestive systems.  Since many illnesses are correlated with either overgrowth or lack of particular gut microbes, it is essential to continue studying the relationship between diet, microbial variations in the gut, and overall health.  

Dr. Shana McQueen