Getting enough calcium

VOL 118 / NO 2 / AUGUST 2005 / POSTGRADUATE MEDICINE

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You can't walk by the dairy case at the supermarket without seeing the word calcium. That's because calcium is an essential mineral that helps build and protect bones and teeth and keeps the rest of the body functioning properly. But how much do you need, and where should it come from?

Why do I need calcium?
Calcium is important for the growth and maintenance of your body. About 99% of calcium in the body is used for bones and teeth. The remaining calcium helps muscles, nerves, and the heart work the way they should.

People who don't get enough calcium may eventually have osteoporosis (bone loss), problems with their jaw and teeth, high blood pressure, and other disorders.

How much do I need?
The need for calcium changes as you age. Children aged 1 to 10 years need about 900 to 1,200 milligrams (mg) of calcium a day. In children, adolescents, and young adults aged 11 to 24 years, the requirement goes up, to 1,200 to 1,500 mg. In general, adults should try to take in at least 1,000 mg of calcium a day. However, women who are pregnant or breast-feeding need more, about 1,200 to 1,500 mg a day. Postmenopausal women aged 50 years and up require 1,500 mg, as do men over age 65.

It's important not to take in too much calcium, because overconsumption of this mineral over time can lead to kidney stones. Most adults can safely consume up to 2,000 mg of calcium each day.

Vitamin D is essential to help the body absorb calcium. Most adults need at least 400 international units (IU) a day. Vitamin D can be found in such foods as fortified dairy products and cereals, as well as some supplements. Daily multivitamins, for example, often contain the full 400 IU.

Which foods are high in calcium?
Dairy products, such as milk, yogurt, and cheese, contain more calcium than any other type of food. Soy milk and other soy products, which are made from soybeans, are also excellent sources of calcium. Soy milk and lactose-free milk are good options for people who cannot drink cow's milk because they are lactose-intolerant.

Green, leafy vegetables, such as romaine lettuce, bok choy, and collard greens, are also good sources of calcium. Other calcium-containing foods include salmon, sardines (with bones), shellfish, almonds, Brazil nuts, and dried beans. Certain foods, such as some types of orange juice and bread, are fortified with calcium.

Some foods and drinks should be avoided because they can sap the body's supply of calcium. These include caffeinated coffee and soft drinks.

Do I need to take a calcium supplement?
It's better to get enough calcium from the diet, because calcium in foods is generally better absorbed than that in supplements. However, the average US woman gets only 625 mg of calcium a day--the average US man only 865 mg--from foods. Because this is far below the amount of calcium required, many people find it convenient to take a daily calcium supplement that also contains vitamin D. No more than 500 mg of calcium should be consumed at a time, however, because the body can't process much more than that.

It doesn't matter what form of calcium supplement you take as long as you're getting enough. Check the label to see how many milligrams of elemental calcium are in each pill. Many people take calcium carbonate in the form of antacids. Take the pill with food and 8 oz of water to help the body better absorb the calcium.

In addition to supplements, daily weight-bearing exercise (such as walking or aerobics) helps maintain strong bones.

Amount of calcium contained in certain foods Food Calcium (mg) Swiss cheese (2 oz) 530 Milk (8 oz) 300 Yogurt (6 oz) 300 Sardines (with bones) (2 oz) 240 Cooked turnip greens (6 oz) 220 Almonds (3 oz) 210 Information from MEDLINEplus (http://www.nlm.nih.gov/medlineplus/ency/article/002412.shtml).

This information is not a substitute for medical treatment.

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