Why Does It Happen?

The gradual loss of bone is a normal part of the aging process and it happens to both men and women. Osteoporosis, however, is due to an accelerated loss of bone and it may affect four times as many women as men. This rapid loss of bone, which begins after menopause, is believed to be caused by the decline in estrogen, a hormone that is essential for the absorption of calcium, a key mineral in bone formation. During childhood and early adulthood, old bone is continually being replaced by new bone until we develop our peak bone mass at around age 30. At that point, the production of new bone begins to slow down, and old bone begins to wear away. After menopause, the rate of bone loss

begins to speed up. In fact, women begin to lose 1 to 1 1/2% of their bone mass annually for about a decade, when the loss begins to level off. Some women lose bone at an even faster rate--2 to 4%-- making them especially vulnerable to fractures.

Studies have shown that most women underestimate the seriousness of this problem; in fact, three out of four post-menopausal women have never discussed osteoporosis with their doctors. Women clearly do not view bone loss with the same urgency as they do cancer or even heart disease. This can be a serious mistake. About 40% of all post-menopausal women will develop vertebral fractures that can result in a rounded back or "dowager's hump." More than 300,000 women will get hip fractures, which not only leave many permanently disabled but can be deadly: about 20% of all women who fracture their hips die within six months of the injury due to complications such as pneumonia. Fortunately, there are many things that can be done to reduce the risk of developing osteoporosis, or to prevent a mild case from turning into a serious one.

Back to top

Keeping Bones Healthy

Getting an Accurate Diagnosis

Given the prevalence of osteoporosis, it is advisable for every woman to have a bone density test at around the time of menopause. All women who have had a surgically induced menopause, those with infrequent or absent periods, especially if they exercise a great deal, and those who suffer from anorexia nervosa also need a bone density scan.

Men need to have a bone density test if they have one or more major risk factors: hypogonadalism (low pooled testosterone); ethanol abuse; have had a bone fracture from a minor trauma or have shown signs of osteoporosis on a radiograph.

The fastest and most accurate test is the dual-energy X-ray absorptiometry (DXA or DEXA). During this test, you lie on a table and an X-ray machine assesses the thickness of your bones. From this simple and painless procedure, a doctor can determine early signs of excessive bone loss and prescribe appropriate treatment.

Building and Maintaining Strong Bones

Calcium and vitamin D are essential for strong bones, yet most women get only a fraction of the calcium they need through diet. Dietary calcium is more easily absorbed than supplements so it's important to eat as many calcium-rich foods as possible. Low-fat dairy products, leafy green vegetables, and canned salmon or sardines with bones are calcium-rich foods. Although it is not a cure for osteoporosis, there is some evidence that calcium supplements combined with vitamin D can help slow bone loss. Post-menopausal women should take 1,500 mg. of calcium daily with 400 IU of vitamin D; those who have not yet gone through menopause need 1,000 mg. of calcium daily with 400 IU of vitamin D. There are many different forms of calcium on the market; calcium citrate is one of the best absorbed.

Men also need to maintain high intakes of calcium as they age because it may help protect against heart attack and because if the smoke or drink excessively—-both of which interfere with calcium uptake--they may experience bone mass loss over time.

Exercise

Weight-bearing exercise (walking, jogging, running) can help maintain bone mass. A little exercise goes a long way. According to a recent study, women who walk as little as one mile a day show significantly less bone loss than non-walkers, especially in their legs and torso. Interestingly, although Japanese women consume little calcium and are also at high risk of osteoporosis, the incidence of hip fractures in Japan is half that of the United States. The reason? Researchers suspect it's because Japanese women often sit on the floor, and the action of getting up and down throughout the day may exercise their hip bones.

Hormone Replacement Therapy

Estrogen replacement therapy is one of the few treatments approved by the FDA for osteoporosis. Recent research data show that estrogen might have a direct action on osteoblasts, the cells that form new bone, to ensure optimal bone architecture. Estrogen also appears to slow the loss of bone. According to recent studies, estrogen can reduce the risk of fractures by about 50%. More important, estrogen can help prevent fractures even in cases of already established osteoporosis.

Rx Treatments

If women cannot or do not want to take hormone replacement therapy, there are two drugs that may be even more effective against osteoporosis. The first is alendronate sodium (Fosamax). This drug was the first non-hormonal treatment approved by the FDA for osteoporosis. Available by prescription only, alendronate is one of a new class of drugs called the bisphosphonates. They work by slowing down the activity of cells called osteoclasts, which resorb bone, thus allowing the activity of bone-building cells (osteoblasts) to dominate in the constant process of bone turnover. Like another medication that increases bone density, nasal calcitonin, alendronate seems to increase bone density for only a few years, and then apparently the situation stabilizes.

A new, slow-release form of fluoride combined with calcium citrate has been shown to reduce spinal fractures and, more important, build bone in older women with severe osteoporosis. This is the first treatment for osteoporosis that has been proven to not only slow the loss of bone but to actually create new bone. Studies performed at the University of Texas Southwestern Medical Center followed women who were taking the fluoride-calcium combination for three to four years. At the end of the treatment, bone mass in the hip bones grew by more than 2% annually. The women in this study had far fewer spinal fractures than women with osteoporosis who were only taking calcium, and suffered significantly less back pain. As of this writing, this drug is pending FDA approval and will be available by prescription only.

This research was done only on women, as is so much of osteoporosis research. Here is another field in which there is the missed opportunity to study both genders. By looking at bone loss in men, scientists could develop a more accurate understanding of the full dynamics of bone loss in human beings.

Adapted and expanded from: What Women Need To Know: From headaches to heart disease and everything in between; Marianne Legato, M.D., and Carole Colman; Simon and Schuster, 1997. Used with permission of the publisher.

Back to top

Interesting Facts About Bones and Osteoporosis in Men and Women

In men, bone mass continues to increase until about age 26, but in women bone mass plateaus before age 20. But even though bone mass plateaus, women can consolidate bone strength for many more years. According to an article titled Women and Nutrition, by Dori Stehlin, in the FDA Consumer Report (Jan./Feb. 1991):

Type I osteoporosis (less severe than type II) affects women six times more frequently than men, while type II (senile osteoporosis, seen in people older than 70) affects twice as many women.

The body clock has differing effects on the ability of the kidney to absorb calcium in men and women. This may help explain the greater bone loss women suffer compared to men. Women's kidneys conserve less calcium than men's, a minor difference that might have a significant effect over the course of a lifetime.

The rate of bone loss in the hip is a third more rapid in women than in men, and in the spine, men lose only a quarter of the bone density that women lose.

Women who exercise so much that their periods stop have an estrogen deficiency that promotes bone resorption and lowers bone mass.

A woman's risk of hip fracture is equal to the combined risk of developing breast, uterine and ovarian cancer.

Back to top