CHAPEL HILL - Calcium supplements moderately reduce the risk of recurring polyp growth in the colon and appear to reduce the risk of colon cancer, according to a new national study. Most physicians already believe calcium supplements delay the age-related, bone-thinning condition known as osteoporosis.
The study, published Thursday (Jan. 14) in the New England Journal of Medicine, involved a four-year follow-up of 832 patients who had polyps removed. Doctors consider polyps in the colon, also called colorectal adenomas, a strong precursor to cancer.
Researchers found 31 percent of 409 patients randomly selected to receive 1200 milligrams of calcium carbonate daily developed one or more polyps during the study. Thirty-eight percent of 423 volunteers who received an inactive compound, or placebo, showed new polyp growth.
"In the treatment group, we found overall a 24 percent decrease in the number of polyps and a 19 percent decrease in the risk of recurrence," said Dr. Robert Sandler, professor of medicine at the University of North Carolina at Chapel Hill School of Medicine. "This represents a significant, although moderate, reduction in the risk of recurrent colon adenomas."
A chief researcher in the study and co-director of UNC-CH's Center for Gastrointestinal Biology and Disease, Sandler praised calcium supplements as safe and probably somewhat effective in preventing colon cancer and slowing osteoporosis.
"People who have had adenomas in the past still need to have regular colon examinations by their physicians," he said. "We need more research on preventing colon cancer because this work is not the final answer."
Patients were treated at six clinical centers at the Cleveland Clinic Foundation, the Dartmouth-Hitchcock Medical Center and the universities of Iowa, Southern California, Minnesota and North Carolina. Dr. John Baron of Dartmouth-Hitchcock was overall study director.