Along with his colleagues from Harvard Medical School, Dr. Raaj Mehta proposed that diets high in whole grains and fiber have a positive impact against colon cancer. In particular, whole grains and fiber fight off a stomach bacteria known as Fusobacterium nucleatum. Fusobacterium is an inflammatory bacterium that blocks the immune response, which signals cells to attack tumor cells in the colon. Doctor Raaj and his colleagues studied the diets of 137,000 people over a 30 year span and tested samples of colorectal tumors. The conclusion of their study states that making healthy dietary decisions is the first course of action to reduce the risk of colorectal cancer.