Animal-based diets may contribute to the development of inflammatory bowel disease, according to a Harvard study published this week in Nature. Eleven healthy volunteers consumed either animal-based or plant-based diets for five days. The volunteers on the animal-based diet had an eight-fold increase in the gut population of a bacterium that may cause inflammatory bowel disease, Bilophila wadsworthia. Growth of this bacterium may be stimulated by the digestion of dairy products. In contrast, the gut population of B. wadsworthia fell three-fold in the plant-based diet group. In addition, gut concentrations of a compound linked to liver cancer, deoxycholic acid, rose in the animal-based diet group. The authors note that diet may contribute to the development of inflammatory bowel disease via changes in gut microbes.

David LA, Maurice CF, Carmody RN, et al. Diet rapidly and reproducibly alters the human gut microbiome. Nature. 2013;505:559-563.