Scientists at the University of California, Davis, are recruiting women for a three-year clinical trial to examine the effectiveness of estrogen-like compounds derived from soybeans in preventing bone loss associated with menopause.

During the first five years after menopause, women may lose 5 percent of their bone mass, greatly increasing their risk of osteoporosis.

"Previous research indicates that soybeans, with their naturally occurring estrogen-like compounds, may help prevent osteoporosis," said Marta Van Loan, an associate adjunct professor in the UC Davis nutrition department and a researcher at the U.S. Department of Agriculture's Western Human Nutrition Research Center.

The participants must be healthy, postmenopausal women younger than age 65 years, who don't smoke. Also, they must not be taking hormones or bone-building or cholesterol-lowering medications. In addition, they must be willing to discontinue their own supplements and take calcium and vitamin D supplements provided by the study.

The women must also be willing to be randomly assigned to one of three groups, receiving either a placebo, lower-dose soy isoflavone tablets, or higher-dose soy isoflavone tablets daily for three years. They also must avoid eating soy foods such as tofu.

Women who have used hormone therapy during the past year, have osteoporosis or have taken anti-osteoporotic medications are not eligible for the study.

All women who are determined to be eligible will make six scheduled visits to the Veterans Administration Mather Medical Center in Sacramento during the three-year study. During each visit, participants will complete health and medical, nutrition, and physical-activity questionnaires. Measurements will be made of height and weight, body composition, blood pressure and bone density.

"We're hopeful that this study will help to determine the effectiveness of two doses of soy isoflavones and that this information eventually will lead to the development of a safe and practical alternative for preventing bone loss in early postmenopausal women," said Van Loan.

Women interested in participating in the study will receive a free bone scan, with results and explanation, to determine if they meet the eligibility criteria. Each woman who completes the study will receive information about her bone-mineral density, physical activity, and dietary intake at the conclusion of the three years. In addition, participants will be paid for their visits to the university research laboratory.

This long-term study is funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases, a branch of the National Institutes of Health, and is being conducted by researchers from UC Davis in conjunction with researchers from Iowa State University.

Women interested in participating in the study should contact the UC Davis research team at (530) 752-4168, extension #3, or send an e-mail to soy4women@whnrc.usda.gov.