Colorectal cancer has been linked to carbohydrate-rich western diets, but the underlying mechanisms have been unclear. A study published by Cell Press July 17th in the journal Cell shows that gut microbes metabolize carbohydrates in the diet, causing intestinal cells to proliferate and form tumors in mice that are genetically predisposed to colorectal cancer. Because gut microbes also contribute to the development of colorectal cancer, Martin and his team suspected that they could interact with diet to explain how the mutations could cause this type of cancer. "By providing a direct link between genetics and gut microbes, our findings suggest that a diet reduced in carbohydrates as well as alterations in the intestinal microbial community could be beneficial to those individuals that are genetically predisposed to colorectal cancer," Martin says.