Patients were randomly assigned to take either calcium carbonate or placebo each day during the four-year study. The team found a modest benefit for those taking calcium. Subjects who received the calcium supplements had a 19 percent decrease in risk of recurrence of any polyps and a 24 percent decrease in the number of polyps. Polyps were detected with colonoscopy exams after nine months and again after four years of entering the study. The associations we found could not be explained away by other dietary differences among participants.
Colorectal cancer is the second leading cause of cancer death in the United States.
In past studies, a high-fat diet has been associated with a higher risk of developing colorectal cancer, while a diet low in fat and high in fiber has been linked to a lower risk. Fruits and vegetables, packed with minerals like calcium, vitamins and other protective nutrients, may help rid the body of these same acids. In animal studies, researchers have shown that calcium can bind to the acids, possibly protecting the intestine and bowel from damage. Until now, data from human studies has been less clear-cut. Observational studies of populations have compared the calcium intake of those who have colorectal cancer to those who have not.