The school has received $5.5 million for two and a half years and will examine whether soy affects the progression of atherosclerosis - a thickening of the artery walls - as well as bone health, cognition, and menopausal symptoms (such as hot flushes) in 300 women.
"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 Howard Hodis, professor of medicine and preventive medicine at the Keck School.
Millions of women have taken hormone replacement therapy (HRT), a combination of estrogen and progestin to ease menopausal symptoms. In recent years, however, HRT has received a mixed press, provoking scientists to look for alternative ways to promote good health among postmenopausal women.
"There really is probably no other alternative available for women looking for postmenopausal comfort and health," said Hodis. "That is why research on soy's effects is important for women's future well-being."
Half of the 300 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 drinks and foods, while the bar is chocolate-flavored and ready to eat.
Atherosclerosis can cause heart attacks, angina and strokes and such cardiovascular diseases are 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.
Last year, Chinese researchers suggested soy isoflanones could help prevent hip fractures in post-menopausal women with low bone mineral content.