Many people take calcium to prevent bone loss with age. However to date there are no studies that show effectiveness of taking daily calcium pills! One study found an increased risk of heart attacks when taking calcium supplements.
Supplemental calcium has potential benefits especially for bone health, however, it may also put people at increased risk of kidney stones, cardiovascular disease and adverse gastrointestinal symptoms.
This is in contrast to calcium consumed from dietary sources, which is usually well-tolerated and has been associated with lower risk of fractures, colon cancer, kidney stones and hypertension.
The best way to get dietary calcium is from dairy products, such as milk, yogurt and cheese, all of which are rich natural sources of calcium. Nondairy sources include vegetables such as Chinese cabbage, kale and broccoli.
Certain conditions like ulcerative colitis, kidney failure, pregnancy, diuretic medications, and weight-loss surgery can all lead to calcium deficiencies, and these patients however may need a calcium supplement.