Western diets are generally carbohydrate-rich, which is associated with colorectal cancer. Previously, the mechanism behind this was unclear. According to a study published in Cell, gut microbes are the link between carbohydrate-rich diets and colorectal cancer. Senior study author Alberto Martin, PhD, and colleagues found that the gut microbes metabolize those carbohydrates to the fatty acid butyrate, which leads to the proliferation of intestinal cells and formation of tumors. Researchers conducted their experiment on mice that were predisposed to colorectal cancer and found that low-carbohydrate diets and antibiotics, which are easy interventions, reduced tumors significantly. In addition, the two treatments reduced gut microbe levels. When the carbohydrates were metabolized to butyrate in the antibiotic-treated mice, researchers found these increased butyrate levels increased the number of tumors in the small intestine, and cell proliferation increased as well. Dr. Martin said this study is critical because it sheds light on an environmental factor of colorectal cancer, which is an aggressive disease. Colorectal cancer is associated with mutations in APC, which is a tumor suppressor gene, and the MSH2 gene, which is important to the reparation of damaged DNA. Researchers said that the gut microbes could explain why the mutations cause this type of cancer as opposed to other cancers.
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.