Although the vast majority of research on the gut microbiome has focused on bacteria in the large intestine, a new study — one of a few to concentrate on microbes in the upper gastrointestinal tract — shows how the typical calorie-dense western diet can induce expansion of microbes that promote the digestion and absorption of high-fat foods.

Several studies have shown that these bacteria can multiply within 24 to 48 hours in the small bowel in response to consumption of high-fat foods. The findings from this work suggest that these microbes facilitate production and secretion of digestive enzymes into the small bowel.

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