Grau MV, Baron JA, Sandler RS, et al. Prolonged effect of calcium supplementation on risk of colorectal adenomas in a randomized trial. J Natl Cancer Inst. 2007;99:129-136.
Calcium has long been known for its role in preventing osteoporosis and growing and preserving healthy bones. Now, according to a current Dartmouth Medical School investigation, it may reduce the risk for colorectal cancer in people who are at high risk for developing cancerous polyps. Researchers examined a group of such patients, and administered them either a 1,200 mg calcium supplement or placebo over 4 years. The calcium group experienced a 17% lower risk for new polyp growth. Incredibly, the calcium appeared to protect these patients against carcinogenesis in the large bowel even more in the years following the study.
Another recent study, however, linked calcium use in men to an increased risk for prostate cancer. More studies must be conducted before researchers can determine if the benefits of men taking calcium to prevent colorectal cancer outweigh the increased risk of prostate cancer.
The study's scientists also stressed that even though calcium appears to offer some protection from malignant polyp growth in high-risk patients, it is not a substitute for proper screening by colonoscopy. Additionally, the National Cancer Institute stresses that calcium intake should come from proper nutrition, rather than supplements.