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So Soy: Studying The Impact Of Soy On Postmenopausal Women

June 16, 2004
University Of Southern California
The National Institutes of Health is sponsoring a trial at the Keck School of Medicine of USC that explores the health effects of soy in postmenopausal women.

The National Institutes of Health is sponsoring a trial at the Keck School of Medicine of USC that explores the health effects of soy in postmenopausal women.

Currently funded at $5.5 million for 2 1/2 years, the clinical trial will examine whether soy affects the progression of atherosclerosis - a thickening of the artery walls - as well as bone health, cognition, menopausal symptoms (such as hot flashes) and other issues related to women’s health.

Howard N. Hodis, professor of medicine and preventive medicine at the Keck School of Medicine, is principal investigator of the new Women’s Isoflavone Soy Health, or WISH, trial, which is supported specifically by the NIH’s National Center for Complementary and Alternative Medicine.

“This is the first randomized, double-blind, placebo-controlled, long-term study on soy protein isoflavones and vascular disease and other postmenopausal health-related issues,” said Hodis, director of the USC Atherosclerosis Research Unit. “We’re very fortunate to be selected to do this trial.”

Building on a history of steady research contributions in the field of cardiovascular disease prevention and women’s health issues, the university’s atherosclerosis research team is focusing on reducing atherosclerosis in postmenopausal women through alternatives to current hormone therapy.

Millions of women have taken hormone replacement therapy, or HRT, a combination of estrogen and progestin to ease menopausal symptoms. Over the last several years, however, current HRT regimens have become controversial, marred by misinterpretation, over-interpretation and overgeneralization of data from highly publicized trials such as the Women’s Health Initiative, Hodis said.

Because of that, medical scientists have begun looking for alternative ways to promote good health among postmenopausal women without using current HRT regimens as physicians know it today. Soy might help, but without conducting careful studies, physicians cannot know for sure.

“On the heels of the controversies surrounding HRT, there really is probably no other alternative available for women looking for postmenopausal comfort and health,” said Hodis, who also is professor of molecular pharmacology and toxicology at the USC School of Pharmacy. “That is why research on soy’s effects is important for women’s future well-being.”

Hodis and colleagues are recruiting 300 participants for the soy study. The recruits must be postmenopausal and in good health, with no coronary heart disease or diabetes.

Women will receive free, routine tests when they enter the trial and at other times as they progress through the study. These include non-invasive ultrasound imaging of the arteries in the neck (a measure of atherosclerosis), as well as cholesterol and blood pressure measurements, dietary assessment, bone mineral density scans, mammograms, pelvic exams, noninvasive electrical recording of the heart and a test of thinking skills.

Half the women will be given a powder or bar (or both) containing soy protein isoflavone, while the other half will receive a placebo powder or bar (or both). They can mix the powder into main dishes, drinks, cereal and other foods, while the bar is chocolate-flavored and ready to eat.

“The idea is to give women a variety of options on how to take the soy,” Hodis said.

Over the 30 months of the trial, women must be willing to come to the Health Sciences campus every one to two months for an evaluation and ultrasound measurements.

Atherosclerosis is a looming issue for aging women, Hodis said.

An accumulation of cholesterol-containing plaques in the arteries, atherosclerosis can cause heart attacks, angina and stroke. Such cardiovascular disease is the number-one cause of death among American women. Before women reach menopause, their naturally occurring estrogen tends to protect them from cardiovascular disease, but when estrogen levels plummet after menopause, atherosclerosis progresses more quickly and cardiovascular disease risk rises.

Preliminary work indicates that soy isoflavones can slow the progression of atherosclerosis. These plant compounds have both estrogen- and antiestrogen-like actions and are much weaker than human estrogen. Scientists think they might offer the protective effects of human estrogen, without estrogen’s potential side effects.

And the effects might not stop at cardiovascular health. Hodis and collaborators at the Keck School have successfully garnered further funding of $2 million from the NIH to investigate the effects of soy on other postmenopausal health issues:

Robert K. Rude, professor of medicine, will investigate whether soy isoflavone supplementation preserves bone density - thereby reducing the risk of bone fractures.

Anna H. Wu, research professor of preventive medicine, will study changes in breast tissue density - measured by mammography - which is related to breast cancer risk.

Juan Felix, professor of obstetrics and gynecology and clinical pathology, will examine how soy affects women’s endometrial tissue and their menopausal symptoms.

And biostatistician Wendy J. Mack, associate professor of preventive medicine and researcher with the USC Alzheimer Disease Research Center and Atherosclerosis Research Unit, will oversee measures of cognition in study participants over time, to see if soy has any relationship to thinking and reducing dementia.

For information on the study or a preliminary eligibility interview by phone, call (866) 240-1489 (toll-free) or (323) 442-3658 between 8 a.m. and 3 p.m. Mondays through Fridays. Information is also available at

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University Of Southern California. "So Soy: Studying The Impact Of Soy On Postmenopausal Women." ScienceDaily. ScienceDaily, 16 June 2004. <>.
University Of Southern California. (2004, June 16). So Soy: Studying The Impact Of Soy On Postmenopausal Women. ScienceDaily. Retrieved April 28, 2017 from
University Of Southern California. "So Soy: Studying The Impact Of Soy On Postmenopausal Women." ScienceDaily. (accessed April 28, 2017).