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Calcium

Calcium is a mineral important for strong bones and teeth. It also helps your heart, nerves, muscles, and other body systems work properly. Milk and dairy products, such as cheese and yogurt, give you most of the calcium you get from food, but you can also get it from nuts, green leafy vegetables, and calcium-enhanced orange juice. Vitamins A, C, D, and E help you use the calcium you get from food. Stress and lack of exercise can harm your calcium balance. Most people in the United States, especially women, do not get enough calcium in their diet.

Uses

Getting enough calcium can help your body do the following.

Dietary Sources

The richest sources of calcium include cheeses (Parmesan, Romano, Gruyère, Swiss, Provolone, Monterey Jack, Edam, Cheddar, Muenster, Gouda, Tilsit, Colby, Caraway, Brick, Roquefort, Port du Salut, Cheshire, Havarti, Fontina, Mozzarella, Feta); wheat-soy flour; blackstrap molasses; and rennin.

Other good sources of calcium include almonds, bok choy, brazil nuts, broccoli, cabbage, caviar, dried figs, greens (dandelion, turnip, collard, mustard, kale), hazelnuts, ice cream, milk, oysters, sardines, soybean flour, and yogurt.

You can also get calcium from many herbs, spices, and seaweeds (for example, basil, chervil, cinnamon, dill weed, fennel, fenugreek, ginseng, kava kava, kelp, marjoram, oregano, parsley, poppy seed, sage, and savory).

Other Forms

Calcium is available in many forms. Lead has been found in some types, so use caution when choosing a product. Lead is a toxic metal that can harm the brain and kidneys, and can reduce red blood cell production. Children are most at risk for lead poisoning. The following are some of the available forms of calcium.

You should be cautious with products that may contain harmful levels of lead. These include unrefined calcium carbonate from oyster shells or limestone, bone meal, and Dolomite.

How to Take It

You should take small doses throughout the day, and drink 6 to 8 cups of water throughout the day to avoid constipation.

Precautions

Do not take extremely large doses of calcium (5,000 mg per day, or 2,000 mg per day or more over a long period) without talking with your health care provider. High doses can cause kidney stones and other serious problems.

Avoid calcium products that contain harmful levels of lead (see above).

Talk with your provider about your calcium needs if you have any thyroid or kidney problems, or if you have hormone or vitamin deficiencies.

Possible Interactions

Calcium can interfere with the absorption of tetracycline.

Some corticosteroid medications such as glucocorticoids also inhibit the absorption of calcium, thereby increasing the risk for osteoporosis over time.

Two different classes of diuretics interact with calcium in opposite ways—thiazide diuretics such as hydrochlorothiazide can raise calcium levels in the blood, while loop diuretics such as furosemide and bumetanide can decrease calcium levels.

High levels of calcium may increase the likelihood of a toxic reaction to digoxin, including symptoms of arrhythmia (irregular heartbeat); however, low levels of calcium render digoxin ineffective. People who are taking digoxin should have calcium blood levels monitored closely.

Supporting Research

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