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Soy Protein Relieves Arthritis Symptoms in Men

Healthnotes Newswire (May 12, 2005)—Taking a soy protein supplement might reduce men’s pain and disability from osteoarthritis, according to a study in Phytomedicine (2004;11:567–75).

Osteoarthritis, a joint condition caused by wearing down of the cartilage that cushions bones where they meet, is characterized by symptoms such as joint pain, stiffness, and inflammation. Anti-inflammatory and pain-relieving medicines are used to relieve symptoms but do not prevent continued cartilage degeneration. Supplements containing glucosamine sulfate, chondroitin sulfate, or both are increasing in popularity and research has demonstrated their ability both to relieve symptoms and to reduce cartilage breakdown. Antioxidant and anti-inflammatory herbal and nutritional therapies are also used to treat osteoarthritis.

Isoflavones are soybean components that are best known for their ability to modulate estrogenic activity in the body by binding to the surfaces of cells in the same places as estrogen (estrogen receptors). Laboratory and animal research have suggested that soy isoflavones can reduce inflammation, improve the condition of cartilage tissue, and reduce pain.

In the current study, 135 people with known or presumed osteoarthritis of the knee were randomly assigned to receive either a milk protein supplement or a soy protein supplement twice a day for three months. The protein supplements provided 40 grams of protein, 1,400 mg of calcium, and 200 IU of vitamin D per day. The soy supplement provided 88 mg of isoflavones per day while the milk supplement had no isoflavones. Range of motion in both knees was measured and questionnaires to evaluate pain level, ability to function, and use of pain-relieving medications were answered at the beginning of the study and monthly during the study. Blood tests were performed at the beginning and end of the study.

In women, arthritis symptoms were similar in those using the soy protein and those using the milk protein, and there was little reduction in pain and no reduction in medication use with either supplement; in men, however, significant reductions in pain and medication use, as well as improvements in daily functioning, were observed in those who used the soy protein but not in those who used the milk protein. Blood levels of a protein that reflects the degree of cartilage breakdown decreased significantly, indicating that there had been less cartilage breakdown in men using the soy protein but not in men using the milk protein nor in women using either protein supplement. Knee range of motion improved significantly after three months in men and women in both the soy protein and the milk protein groups.

The results of this study provide preliminary evidence that soy protein might relieve the symptoms of osteoarthritis in men, though possibly not in women. While it is not known why men and women responded differently in this study, it may have something to do with the differences between sexes in estrogen levels and in the density of estrogen receptors. In light of these promising findings, further research into the effects of soy protein and soy isoflavones on osteoarthritis is warranted.

Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.

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