Osteoporosis

Also read Osteoporosis: What is it? Prevention and Treatment
and Antiporosis: The Osteoporosis Plan

The best way to avoid osteoporosis when you're old is to eat-and run-now, here, the complete guide to good bones forever.

We Americans are a practical people; we like to nip problems in the bud. And nowhere can this heads-up attitude stand us in better stead than in the prevention of bone loss. Often thought of as an elderly person's disease, osteoporosis is something women won't have to worry about if they take a few steps to prevent it while they're young.

Most of us shrug off bone loss as a normal part of aging, gulping calcium supplements only when reminded by a news report. Contradictory medical reports and frightening statistics also have a way of inspiring inertia more often than action. But the key to prevention is a surprisingly simple strategy doctors call bone banking--stocking up on a healthy supply of calcium and exercising as regularly as you can, whether you're in your twenties or forties, and keeping it up. "It's like an IRA or some other long-term savings account," says Nicholas DiNubile, MD, a sports medicine specialist and orthopedic surgeon for the Pennsylvania Ballet. "If you have a good account going into retirement, you'll have a comfortable old age."

"We have to start fighting osteoporosis now," says Laura Tosi, MD, an orthopedic surgeon at Children's National Medical Center. "This is the ultimate women's issue." She's not exaggerating: The disease affects more than 20 million American women, and it hits them harder than men mainly because they have 10 to 30 percent less bone mass and lose their sex hormones (believed to protect against bone deterioration) about twenty years earlier. Men also tend to weigh more than women, do more weight-bearing work, play more sports, and eat more--so they get more calcium.

How much bone you start with has a lot to do with genetics. Medical experts say because black and Mediterranean women tend to have heavier bones than white or Asian women, they are less susceptible to osteoporosis. And any heavy or big-boned woman is also at lower risk.

How much you keep, however, has a lot to do with you. Overdrinking, smoking, eating a diet too high in sodium and protein, or leading a sedentary life can all contribute to osteoporosis. "Think of bone health as a three-legged stool," says Robert Heaney, MD, a researcher at Creighton University, in Omaha, Nebraska. "One leg is calcium, another is hormones, and the third is exercise. You can't sit on the stool unless it has all three legs." Though the interaction of each factor is not fully understood, doctors are loath to omit one.

The bulk of the skeleton is laid down in childhood and adolescence, when bone-building cells (osteoblasts) outperform bone-eroding cells (osteoclasts). Bone density peaks anywhere from age fourteen to the late twenties, and from then until about age thirty-five, bone density pretty much stabilizes. After that, building lags behind erosion, and bone is lost. It's not fast--about 1 percent a year--but by age fifty that can add up to 15 percent.

The first issue in preventing osteoporosis is getting enough calcium, but there's wrangling over how much is enough. The current U.S. Recommended Daily Allowance for women over twenty-five is 800 milligrams. Last June the National Institutes of Health Consensus Development Conference on Optimal Calcium Intake upped that to 1,000 milligrams for women over twenty-five and menopausal women on estrogen replacement therapy (1,500 milligrams for women not on ERT).

Judging from the estimated $200 million Americans ponied up for supplements last year, calcium is big business, but doctors push dairy products and green leafy vegetables as the preferred sources of the mineral. "We can't really concoct a satisfactory intake based on just supplements yet," says John J.B. Anderson, PhD, a professor of nutrition who hosted last year's symposium on "The Role of Nutrients in Bone Health and Osteoporosis Prevention" at the University of North Carolina at Chapel Hill. "[The NIH conference] didn't do justice to the other nutrients. We tried to plug in the roles of vitamin D, vitamin K, magnesium, and other micronutrients." Getting a proper balance--rather than megadosing specific nutrients--is the idea, both to avoid overlooking a potential player and to prevent an excess of one, like magnesium, from interfering with the absorption of another, like calcium. For example, vitamin D is essential for calcium metabolism, but too much can actually cause calcium loss.

Vitamin D has also been fingered in the much-ballyhooed discovery of an "osteoporosis gene." In the January 1994 issue of the journal Nature, Australian researchers reported a link between a defect in the vitamin D receptor gene and an increased risk of osteoporosis. "There was a lot of hype about that, but by no means is it as gloomily predictive as suggested," says Robert A. Lindsay, MD, director of the Metabolic Bone Disease Unit at New York City's St. Luke's-Roosevelt Hospital.

Operating on the use-it-or-lose-it principle, weight-bearing exercise (activities in which you actually carry your own weight around, such as walking, running, stair climbing) is vital in childhood, when bone is being amassed. Once peak bone density is reached, not only is exercise a maintenance tool, but it yields such serendipitous side benefits as improved flexibility, balance, and muscle strength. "If you've got strong muscles, you've got to develop strong bones. Almost any exercise contributes to protection from falling and produces a positive stress on the skeleton," says Dr. Lindsay, who's also president of the National Osteoporosis Foundation (NOF).

The NOF recommends one hour of weight-bearing activity--for instance, brisk walking (faster than a stroll, slower than when you're late for a meeting)--four to six days a week. This prescription doesn't rule out nonweight-bearing activities, like swimming or yoga. Small preliminary studies looking at bicycling, underwater workouts, and t'ai chi have shown modest improvements in bone density in postmenopausal women. Working out with weights is also recommended for building muscle strength, which, in addition to benefiting bone, Dr. DiNubile says, can help absorb shock from falls.

As with nutrition, striking a healthy balance is the goal here. Taken to the extreme, exercise can lead to a form of osteoporosis that strikes young women who suffer from the "female athlete triad." These women typically are significantly underweight (from exercising too much, not eating enough, or a combination of the two), which leads to a disrupted menstrual cycle, which leads to bone loss, dramatically illustrating the role estrogen plays in osteoporosis. (Interestingly, though, in a study conducted by Michelle P. Warren, MD, an endocrinologist at St. Luke's-Roosevelt Hospital, the bone density of young amenorrheics treated with estrogen-progestin did not improve, hinting at influences beyond estrogen.)

For menopausal women, ERT remains the focus of osteoporosis prevention. Since the hormone is believed to hamper bone-eroding cells, once it's gone, bone loss can increase from the premenopausal rate of 1 percent a year to as much as 2 to 3 percent a year for three years or longer (and then it slows again). ERT has been shown to reduce the risk of hip fractures by 50 percent over the long term--spurring doctors to write more than 44 million prescriptions for Premarin last year.

Still, ERT has been mired in controversy lately. And going to the experts doesn't guarantee clear answers: Last June, The New England Journal of Medicine published a study linking ERT with breast cancer, only to be contradicted in July by a study in The Journal of the American Medical Association.

This is the reason a woman approaching menopause needs to assess her risk of both osteoporosis and breast cancer. If a woman is considering ERT for its bone-saving benefits, her doctor may suggest a bone-mineral density test to determine whether the therapy is necessary. This test can tell a woman how much bone she has and how much she's lost--providing a pretty good predictor of her risk of fracture.

For women diagnosed with osteoporosis who can't or won't undergo ERT, there are only two other FDA-approved treatments. One is calcitonin, a natural hormone produced by the thyroid gland believed to slow bone erosion. Though it's reported to have relatively few side effects, the calcitonin-salmon preparation generally used is expensive (more than $6 per dose), and a woman has to inject herself every other day. The FDA recently approved a more easily administered nasal-spray form of calcitonin (Miacalcin, just released from Sandoz Pharmaceuticals). The other approved therapy is sodium alendronate (marketed by Merck under the name Fosamax), one of the new bisphosphonate drugs that have been shown to inhibit bone loss. Juicing up the cells that build bone rather than retarding the cells that erode it is the latest strategy being investigated. Clinical studies looking at sodium fluoride, parathyroid hormone, and a combination of fluoride and calcium are now under way, but answers are nowhere near imminent.

Just as bypass surgery is not the preferred strategy for heart disease, undergoing drug therapy to restore lost bone isn't the recommended approach to osteoporosis. Instead, focusing on prevention rather than hoping for a cure is your best line of defense. As Dr. Tosi says, "This is one area where you can make a huge difference in your life."

THE CALCIUM CONNECTION

Getting calcium from foods is not always easy. A can of sardines with a side of kale may serve up more than 450 milligrams of calcium, but try ordering that from the corner deli. While dairy products are the most common source, they're frequently shunned by fatphobes and the lactose-intolerant. But if it's fat that's keeping you from drinking whole milk, 8 ounces of skim milk actually has about 10 more milligrams of calcium (302), and 8 ounces of nonfat or low-fat yogurt delivers about 415 milligrams. With the number of lactase-added products on the market, the intolerant can have their milk and drink it, too. Other sources:

• Tofu: With all the heart-healthy press this soybean curd is getting, people may not realize it's a great source of calcium, too, providing 260 milligrams per cup.
• Designer coffee: A "grande" latte made with 14 ounces of skim milk can deliver 400 milligrams of calcium.
• Seaweed: A staple in Japanese food, sea greens have more calcium than some cheeses (and hardly any calories).
• Green vegetables: The darker they are, the more calcium they have, so broccoli is a good choice (though spinach isn't, because it contains oxalates, which inhibit calcium absorption).
• Supplements: For popularity and absorbability, calcium carbonate and calcium citrate are the winners, hands down. For some people, though, calcium carbonate is rough on the stomach: Taking it with meals and in small doses throughout the day can help, and enhance absorption. A lot of people find calcium citrate easier to digest and can take it between meals. Supplements like calcium lactate and calcium gluconate are easily absorbed, but the pills are expensive, hard to find, and hard to swallow. You'd have to take about nine of them to get the same amount of calcium you'd get from three calcium carbonate pills. On the other hand, chewing one antacid tablet, like an ordinary Tums, is an easy way to get about 400 milligrams. (Just avoid antacids with aluminum, which inhibits calcium absorption.) One hint: A 500-milligram calcium carbonate tablet may contain only 200 milligrams of calcium. What you're looking for is elemental calcium. Check the label.