Soy Protein May Protect Against Osteoporosis

By Peter Russell
WebMD Health News

Reviewed by Brunilda Nazario, MD

Nov. 2, 2015 -- Getting plenty of soy protein from food, or taking soy supplements, could help protect older women from osteoporosis, early results from a new study suggest.

Women become more likely to get that condition, which makes bones weak and brittle, after menopause. That's because their bodies make less estrogen, which protects against bone loss.

Soy-rich foods -- like lentils, kidney beans, lima beans, fava beans, and chickpeas -- contain chemicals called isoflavones, which have a similar structure and function to estrogen. So, a research team led by the University of Hull in the U.K. set out to determine whether soy and isoflavones could help protect women from osteoporosis.

They gave 200 women who were within 2 years of the start of menopause either 30 grams (about an ounce) of soy protein with 66 milligrams of isoflavone, or 30 grams of soy protein on its own, every day for 6 months. They then checked the women's bones by examining certain signs, or "markers," in their blood.

They found that the women on the soy diet with isoflavones had lower levels of one particular marker than the women on soy alone. This suggests that their rate of bone loss was slowing down and lowering their risk of getting osteoporosis. Women taking soy protein with isoflavones also had fewer signs of a risk of heart disease than those taking soy alone, the researchers say.

"We found that soy protein and isoflavones are a safe and effective option for improving bone health in women during early menopause. The actions of soy appear to mimic that of conventional osteoporosis drugs," says Thozhukat Sathyapalan, MD, who led the study.

"The 66 mg of isoflavone that we use in this study is equivalent to eating an Oriental diet, which is rich in soy foods. In contrast, we only get around 2-16 mg of isoflavones with the average Western diet.

"Supplementing our food with isoflavones could lead to a significant decrease in the number of women being diagnosed with osteoporosis."

Bones that become brittle and more fragile are responsible for around 9 million fractures worldwide every year. The National Osteoporosis Foundation estimated last year that more than 10 million U.S. adults over the age of 50 have osteoporosis or osteopenia.

The findings were presented at the Society for Endocrinology's annual conference in Edinburgh.

The researchers say they now want to investigate the long-term health consequences of using soy protein and isoflavone supplements, and whether this may also have other health benefits.

These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.

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SOURCES: Society for Endocrinology BES Conference, Nov. 2-4, 2015, Edinburgh. Press release, Society for Endocrinology. National Osteoporosis Society.

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