Calcium Supplements & Prostate Cancer

Calcium is a dietary mineral needed to maintain healthy bones and teeth. It also helps the nerves, muscles and heart work properly. You can get calcium from dairy, dark green leafy vegetables, fish, grains and fortified cereals and foods. Some people who may not get enough calcium include girls aged 9 to 18 years, women older than 50 years and men older than 70 years. A calcium supplement may supply what you cannot get from food. However, consider your total calcium intake, as taking too much may increase your risk of certain cancers, including prostate cancer in older men. Talk to your doctor about the amount of calcium that is appropriate for you.

Types of Supplements

Dietary calcium supplements are available in two forms: carbonate and citrate. Calcium carbonate contains 40 percent usable calcium, so 500 mg of calcium carbonate has 200 mg of elemental calcium. Calcium carbonate is not expensive and may be found in over-the-counter antacid products. Calcium citrate has only about 21 percent elemental calcium. It is more expensive than calcium carbonate but it can be taken without food. Some people with low levels of stomach acid, including those older than 50, absorb calcium citrate better than calcium carbonate.

Prostate Cancer

Prostate cancer occurs in a man's prostate, the gland that produces seminal fluid for the sperm. It is one of the most common types of cancer in men, especially those over 65 with a family history of prostate cancer, African-Americans and overweight men, according to the American Cancer Society. Diet may contribute to the risk of prostate cancer, and men who eat more red meat and high-fat dairy products may have a higher risk of getting prostate cancer.

Calcium and Risk of Prostate Cancer

A prospective study from Harvard Medical School, Harvard School of Public Health and the Karolinska Institute in Sweden, published in the February 1998 issue of "Cancer Research," investigated the relationship between prostate cancer risk and calcium supplements. Researchers followed up more than 47,781 men for eight years and found the risk of metastatic prostate cancer was three times higher in men who took more than 2,000 mg/day of calcium compared to those who took 500 mg/day. The risk was the same whether the men took calcium supplement or ate dairy products of equivalent amounts.

Protection Against Prostate Cancer

A clinical trial conducted by researchers at Dartmouth Medical School found opposing evidence on the relationship of calcium intake to the risk of prostate cancer. The researchers randomly assigned 672 men to receive either 3 mg of calcium carbonate or placebo daily for four years and followed them up the next eight years for a diagnosis of cancer. Published in the March 2005 issue of the journal "Cancer Epidemiology, Biomarkers and Prevention," the study found that calcium supplement did not increase the risk of prostate cancer. Instead, results suggested that calcium supplement might offer some protection against prostate cancer.

Recommendation

Because of conflicting evidence among the studies, more research is needed to better understand the relationship between calcium supplementation and risk of prostate cancer, notes the Linus Pauling Institute. The Food and Nutrition Board of the Institute of Medicine recommends that men 51 years and older consume 1,000 to 1,200 mg of calcium daily by eating calcium-rich foods and using supplements only as needed, without exceeding the upper limit of 2,000 mg/day.