Calcium maintains strong bones and teeth; regulates muscle contractions; transmits nerve impulses; and helps release essential hormones and enzymes.

How Much: Recommended dietary allowance (RDA) = 1,000 milligrams (mg) daily for adults age 50 and younger; 1,200 mg for those 51 and older. Although some experts recommend 1,500 mg per day for postmenopausal women and adults with inflammatory conditions, the optimal amount of calcium remains controversial. Taking calcium with vitamin D boosts absorption as much as 65 percent.

Too Much: Tolerable upper limit (UL) = 2,500 mg.

Too Little: Contributes to bone loss, tooth loss, muscle cramps and hypertension.

Foods: Low-fat milk, yogurt and cheese; kale, broccoli and spinach; canned sardines and salmon with bones; calcium-fortified cereals, orange juice and soy products.

Interactions: Aluminum-containing antacids, antibiotics, anti-convulsants, bone drugs, corticosteroids, calcium channel blockers, diuretics, laxatives and multivitamins containing iron, magnesium and zinc.

Research Note: Calcium helps prevent osteoporosis – the loss of bone density. Getting enough calcium is crucial for people with rheumatoid arthritis (RA) and those taking corticosteroids – each of which significantly increases osteoporosis risk. In studies, a combination of 1,000 mg calcium and 500 mg of vitamin D reversed corticosteroid-induced bone loss and prevented further bone deterioration. Some research suggests calcium supplements may also slow RA-related joint damage. 

However, research has also uncovered a darker side to calcium: Supplements (but not calcium-rich food) may significantly increase the risk of heart attack. If you take calcium supplements, talk to your doctor about the risks and benefits.