Calcium has important health benefits, but consuming too much calcium may increase the risk of prostate cancer.
Calcium, a mineral abundant in dairy products, is important for maintaining strong bones and teeth and preventing the bone thinning disease osteoporosis. Studies also suggest that an adequate calcium intake reduces the risks of hypertension and colon cancer.
In light of these benefits, the latest Dietary Guidelines for Americans, which were issued in 2005, recommend that all adults consume three cups of fat-free or low-fat milk each day, or the equivalent in low-fat cheese or yogurt. The Institute of Medicine also advises a calcium-rich diet, recommending that men and women over age 50 consume 1,200 mg of calcium per day.
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For older men, the calcium picture is not entirely clear. Accumulating research suggests that consuming too much calcium increases a man’s risk of developing prostate cancer.
In an article published in the December 7, 2005, issue of the Journal of the National Cancer Institute, researchers analyzed 12 studies that examined a potential link between calcium consumption and prostate cancer. They found that men who consumed the most dairy products had an 11% increase in risk compared with men who consumed the least. When they analyzed the results by total calcium intake (dairy products and other sources of calcium), the increased risk was 39%.
Last year, research from the Health Professionals Follow-Up Study (a long-term study of nearly 50,000 male health professionals) also found a link between prostate cancer and a high consumption of calcium. But that study, which appeared in Cancer Epidemiology, Biomarkers and Prevention, associated high calcium intake primarily with advanced and fatal prostate cancer.
Men who consumed 1,500 - 1,999 mg of calcium per day were nearly twice as likely to be diagnosed with life-threatening prostate cancer as were those who consumed 500–749 mg per day; the risk was nearly 2.5 times higher for men who consumed 2,000 mg or more per day. The researchers noted that high calcium levels suppress the active form of vitamin D (1,25-dihydroxyvitamin D3), which is believed to regulate the normal growth of prostate cells. Other researchers have pointed to calcium's effects on insulin-like growth factor-1 (IGF-1), which stimulates the growth of prostate cancer cells.
Bottom line advice on calcium and prostate cancer: Concerns about calcium and prostate cancer need to be put into perspective because calcium has important health benefits. Moreover, in the amounts that most men consume, the increase in prostate cancer risk is modest. The prudent approach, for now, would be to limit calcium consumption to the 1,200 mg per day recommended by the Institute of Medicine. Food sources are the best bet and can quickly add up to 1,200 mg.
