Calcium Reduces Colorectal Cancer Risk

Category: Dietary Supplements , Gastrointestinal (GI) Health

A large, randomized, controlled study, published in the American Journal of Clinical Nutrition (2004, vol 80, issue 5), found that a high intake of calcium supplements reduced the risk of colorectal cancer by an average of 12 percent. Scientists at the National Cancer Institute, the University of Pittsburgh, the University of Minnesota, the University of Texas, MD Anderson Cancer Center, and the University of North Carolina, compared the supplemental and dietary calcium intakes of nearly 3,700 colon cancer participants with nearly 35,000 cancer-free participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO Trial) at 10 centers in the United States (Birmingham, AL; Denver; Detroit; Honolulu; Marshfield, WI; Minneapolis; Pittsburgh; Salt Lake City; St Louis; and Washington, DC). All participants were volunteers in a screening trial and were screened with a standardized sigmoidoscopy procedure. The researchers measured the participants' calcium intake with a detailed questionnaire on food-frequency and calcium supplement use.

At the end of the study, researchers found that greater calcium intake was associated with a reduced risk of colorectal cancer. This association was strongest for calcium from supplements and nondairy food sources, with a 27% decrease in cancer risk for participants taking supplements than for nonusers of supplements. The results for dietary calcium were less clear. Although milk and dairy products include calcium and other anticarcinogenic compounds such as vitamin D and conjugated linoleic acid, dairy foods also contain components that may trigger cancer development, such as saturated fat or insulin-like growth factor.

Calcium reduces the risk of colon cancer in two ways. "Calcium can reduce risk of colorectal tumors by binding bile and fatty acids in the bowel, thus reducing exposure of colonic epithelium to these potentially carcinogenic compounds, or by acting directly on colonic epithelium, influencing cellular differentiation, apoptosis, and associated proliferative activity, probably mediated by the calcium-sensing receptor," the study authors write.

Posted by on December 26, 2008 10:00 AM