Soy Supplement Safety Scrutinized

A national study to determine the safety of over-the-counter soy supplements to prevent osteoporosis in postmenopausal women has been launched by Baylor College of Medicine researchers.

The $4.5 million project will determine the benefits, safety and correct dosages of soy isoflavone supplements. The study will enroll 400 women at three sites across the country and follow them for two years. The Children’s Nutrition Research Center at Baylor is the coordinating site.

“The use of over-the-counter soy isoflavone supplements is becoming common for postmenopausal women as prevention for osteoporosis,” said William W. Wong, M.D., project director and professor of pediatrics at Baylor. “But, no study has been done analyzing its long-term safety and benefits.”

A secondary goal of the study will be to communicate the results in understandable terms to consumers.

More than 20 million American women have osteoporosis. Postmenopausal women are particularly susceptible because estrogen production has stopped. Estrogen replacement has been shown to reduce bone loss and fractures, but it carries some risks.

“Hormone replacement therapy provides many benefits for some women, but the possible side effects have to be weighed,” said Wong. “If we can determine that natural soy isoflavones would be beneficial in preventing osteoporosis, as well as provide relief for some symptoms of menopause, it would be a tremendous service.”

Soy isoflavones have a chemical structure that is very similar to estrogen, with estrogenic activities that are present but in a weaker format, he said.

Preliminary studies have indicated that soy isoflavones can help in preventing osteoporosis and reducing the symptoms of menopause, but those studies were short term, Wong said.

“We need to give women and their physicians an answer regarding whether this works or not, whether it is safe over the long term, and how much should we give,” he said.

In the study, one-third of participants will receive 120 milligrams of supplements a day; one-third will receive 80 milligrams a day; and one-third will receive a placebo. Each participant will take three tablets a day, along with a multivitamin and a calcium supplement.

As part of the study, funded by the Department of Agriculture, a plan has been established to disseminate the results to researchers, educators, health care professionals and consumers through Texas A&M University and the Cooperative Extension System.

Along with the Baylor site, women will be enrolled at the University of Georgia and the University of California at Davis. For more information, call (713) 798-6783.

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©2006 Texas Medical Center

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