Dear HEALTHbeat subscriber,

Soy is a good source of dietary protein. Many people also consider it a power food, one that can help lower cholesterol and possibly help relieve bothersome symptoms of menopause. But, as this issue of HEALTHbeat explains, recent research shows that despite hopes to the contrary, soy extracts do not prevent bone loss in older women. Also in this issue, Dr. Celeste Robb-Nicholson answers a reader question about knee replacement surgery.

Wishing you good health,


Nancy Ferrari
Managing Editor
Harvard Health Publications
HEALTHbeat@health.harvard.edu

• 18 grams (g) of soy protein (about the amount in one cup of tofu) plus 105 milligrams (mg) isoflavone;
• 18 g of animal protein (about the amount in a 3-ounce serving of salmon) plus 105 mg isoflavone;
• 18 g of soy protein plus placebo; or
• 18 g of animal protein plus placebo.

The protein (soy or animal) was consumed as a powder mixed into food and beverages; the isoflavone or placebo was taken in pill form. All the women were told to get at least 1,200 to 1,500 mg of calcium per day.

The women underwent initial bone density testing with dual energy x-ray absorptiometry (DXA) and blood tests for enzymes that indicate bone remodeling activity. During the study their blood was tested for isoflavones to make sure they were taking the pills and powder as directed.

After a year, average bone mineral density had declined equally in all four groups, and bone remodeling enzymes were equally active in all four groups. The researchers concluded that adding soy protein or isoflavone supplements to the diet doesn’t build bone or prevent bone loss in older postmenopausal women. Results were published in The American Journal of Clinical Nutrition (July 2009).

Soy is a good source of protein, but women over age 60 with osteoporosis should talk to their clinicians about other options to protect their bones.

Q: Fifteen years ago, I had surgery for a torn meniscus and was told I had arthritis. I’m now 79, and my knee hurts most days, though I still exercise daily on a stationary bike. I hate to take pills. Should I consider a knee replacement?

A. Twenty years of follow-up data indicate that knee replacement surgery relieves pain and improves function in most patients. However, it’s major surgery, so it’s important to determine if you’re a good candidate. You are if you have 1) x-ray evidence of joint damage, and 2) persistent pain that isn’t relieved by nonsurgical measures and greatly limits your daily function and quality of life. You also need to determine if arthritis of the knee is the actual source of the trouble. The pain could be caused by tendinitis, bursitis, a ligament strain, or even another meniscal injury. Or it could be “referred” from a problem originating in the back or hip. A thorough evaluation by an orthopedic expert is important.

Even if you have x-ray evidence of advanced arthritic changes in the joint, there are noninvasive strategies you can try before considering knee replacement. If you’re overweight, losing weight may help relieve the pain by reducing the load on your knee. Using a cane is another way to decrease the load. A knee brace and shoe inserts can help align the knee and improve weight distribution. You can also do exercises to strengthen the muscles involved in proper knee alignment.

Your knee will hurt less if you limit your physical activity, although that can cause problems associated with inactivity, such as weight gain. To reduce the pain enough to stay active, you can take nonsteroidal anti-inflammatory drugs (Motrin, Advil, others) or acetaminophen (Tylenol, others). Ask your clinician about knee injections of corticosteroids or hyaluronan.

If your knee locks, catches, or gives way, arthroscopy to remove debris or damage in the knee might offer years of improved function while avoiding or at least postponing a full joint replacement.

Knee replacement often, but not always, restores the joint to normal function and makes it more flexible. For people who are good candidates, the risks of knee replacement surgery and the rigors of rehabilitation are usually outweighed by the benefits. From what you’ve written, I would say you’re not yet one of those persons. For now, discuss the nonsurgical options with your doctor; you can always consider knee replacement later, if necessary.

This Question and Answer first appeared in the October 2009 Harvard Women’s Health Watch, available at www.health.harvard.edu/women.