Got Milk? It's Not Enough

A 25-year Harvard study of 72,000 women found a diet including plenty of milk won't prevent a fractured hip or wrist. Women who drank milk twice a day were just as likely to fracture a bone as women who drank it once a week.

Part of the explanation may be that Americans know about calcium, but they consistently underestimate the importance of other nutrients for bone health, especially vitamin D, which fosters calcium absorption. Without it, calcium never finds its way to the bone. A survey by the Society for Women's Health Research found that less than half of women over 50—the population most at risk for bone disease—think that vitamin D is important for maintaining their bones.

Three-quarters of the women incorrectly believe green leafy vegetables contain vitamin D. The only foods that provide vitamin D are fortified milk and orange juice, certain cereals and fatty fish such as salmon and sardines. But the easiest way to get vitamin D is to sit in the sun for 15 minutes a day. Sunlight interacts with skin to manufacture the body's own supply of the vitamin.

Exercise can also stave off osteoporosis. Weight-bearing sports, such as running, jumping and weight lifting, build bone mass. But even gentle exercise can prevent thinning of bones.

Race may also be a factor. A Purdue University study found Caucasian girls lose more calcium in their urine than African-American girls, although both groups lost calcium on a high-sodium diet. This may help explain why one in four Caucasians develop osteoporosis, whereas only one in 10 African-Americans do.

More than 10 million Americans have the disease, and 34 million are at risk for developing it.