Diet can influence the composition and complexity of the gut microbiome in a host. In Nature, Devkota et al. report that diets rich in milk fat skew the microbiome of mice and enhance the propensity of susceptible mice to develop colitis. Milk fat increases taurine conjugation of bile acids, which then promote growth of the sulfite-reducing bacteria Bilophila wadsworthia, an otherwise rare occupant of the microbiome. Germ-free mice can be monoclonized by B. wadsworthia only in the presence of milk fat or taurine but not by other diets. This bacterial colonization leads to higher expression of interleukin 12 (IL-12) and interferon-γ by mesenteric lymph node cells in an as-yet-unknown way. Although wild-type mice do not develop immunopathology, those that lack IL-10 expression are more prone to disease. Thus, diet can represent a major contributing factor to inflammatory bowel disease in genetically susceptibile people.

Nature (13 June 2012) doi:10.1038/nature11225