What are the warnings for calcium supplements?

Although there are some warnings to know about, calcium is generally safe to take at moderate levels. Taking too much calcium may increase the risk of kidney stones for some people. Avoid calcium supplements that contain unprocessed oyster shell, bone meal or dolomite, which could contain lead or other toxic metals. Calcium supplements may cause gas or constipation, but increasing your fluid intake should take care of these symptoms.

Adults under age 50 need 1,000 milligrams (mg) of calcium a day, while women over age 50 and men over age 70 need 1,200 mg daily. The safe upper limit is 2,500 mg for most adults, 2,000 mg for those over 50.