Calcium

Here's how to bone up on this essential mineral

Originally published in Mayo Clinic Health Letter , May 1995

What do you and a 10-year-old have in common?

You both need about the same amount of dietary calcium.

Calcium's role in bone health isn't limited to growing children and teens. In adults, eating too little calcium is linked with osteoporosis. Each year, more than 1.5 million Americans have fractures related to thin, brittle bones.

Last June, scientists convened by the National Institutes of Health (NIH) examined new information about calcium's role in preventing osteoporosis. Their consensus: The recommended dietary allowance (RDA) doesn't adjust for your calcium needs as you grow older.

How much is enough?

The amount of calcium you need varies throughout your life. Greatest needs occur during the period of rapid growth among children and adolescents and among pregnant and nursing women.

After about age 30, the amount of bone you form typically reaches its maximum. Bone formation and bone loss are balanced. For this reason, the RDA for calcium drops from a high of 1,200 milligrams for adolescents to 800 milligrams for adults older than 25.

However, in light of evolving research into calcium-related disorders, the NIH panel recommended higher calcium intakes for adults. (They also recommended more calcium for adolescents to reduce their risk of osteoporosis as they grew older.)

The panel agreed you need more calcium because:

• You absorb less calcium--Calcium absorption decreases as you age, especially after about age 65. You also make less vitamin D--essential for enhancing the amount of calcium that ultimately reaches your bones (see ).

  If you're a woman:

   

• Your estrogen level falls--Estrogen slows calcium loss from bones. At menopause when your estrogen level drops, bone loss accelerates.

  During the first six to eight years of menopause, estrogen replacement therapy slows bone loss. That's why women who take estrogen need less calcium than women who don't take the hormone.

  After about 10 years, estrogen's effects are less dominant and calcium's effects increase. Supplemental amounts of calcium in the range of 1,500 milligrams seem to reduce bone loss.

Ways to get more calcium

To meet the higher calcium recommendations:

• Choose foods first--Dairy products are your richest sources of calcium. Select low-fat items such as skim milk or low-fat yogurt to limit calories and fat.

  If you don't or can't drink milk, some kinds of leafy green vegetables and legumes, plus calcium-fortified products, are other ways to boost your calcium intake.

  To fortify your own foods, add a tablespoon or two of nonfat dry milk to baked goods, casseroles, meatloaf or hot beverages.

   

• Consider a supplement--Depending on your diet, food alone can provide you with recommended amounts of calcium. If your diet doesn't include dairy products, however, you may need a calcium supplement.

Food is the best way to get calcium because it contains a variety of essential nutrients. But if you need a supplement:

• Take small doses--Limit single doses to no more than 600 milligrams of elemental (available) calcium. Your body absorbs small doses best.

   

• Take with meals--Although some foods may interfere with calcium absorption, taking a supplement with meals is most convenient. Many older adults also have reduced levels of stomach acid. By stimulating acid production, eating enhances calcium absorption.

   

• Add vitamin D--If you're not taking a multivitamin, choose a calcium supplement that also provides 200 to 400 International Units (IU) of vitamin D.

   

Keep calcium in perspective