Also known as: Calcium carbonate, calcium citrate.
Potential uses: Calcium supplements can strengthen bones and prevent osteoporosis, or thinning of the bones. Bone loss is of special concern to women who are taking aromatase inhibitors to treat breast cancer, since bone loss is a side effect of all three aromatase inhibitors. Calcium also can help prevent the weakening of bones that can occur with certain chemotherapy medications. Some studies suggest that calcium may help reduce the risk of certain cancers, such as breast and colorectal cancer, but more research is needed. Calcium also plays a role in keeping blood pressure under control.
Usual dose: 1,000 to 1,300 milligrams per day.
Are there any risks? Consuming an excessive amount of calcium — 2,500 milligrams or more per day — can lead to having too much calcium in the blood (hypercalcemia), which can interfere with kidney function and the body’s ability to absorb other minerals. Consider how much calcium you are consuming in your diet — main sources include dairy products and calcium-fortified foods — before deciding how much to supplement. Hypercalcemia from diet and supplements is rare, however.
What does the research show? Some Harvard University studies have found that calcium and Vitamin D may help protect premenopausal women from developing breast cancer. Animal studies suggest that higher levels of calcium and vitamin D may make breast cancer less likely to spread to the bones. Until more research is done in humans, however, calcium cannot be said to prevent or treat breast cancer. Research does show that calcium is important for good bone health.