Soy Might Not Prevent Hot Flashes

By Salynn Boyles
WebMD Health News

Reviewed by Louise Chang, MD

Nov. 2, 2012 -- Tofu, edamame, and soy milk may be healthy foods, but if you are a menopausal woman eating them, they may not do much to prevent hot flashes and night sweats.

That finding comes from a new study of 1,651 women. Researchers from the University of California, Davis, (UC Davis) followed the women for 10 years, starting when the women were in their 40s and early 50s.

None had menopause-related hot flashes when they enrolled in the study, but many experienced them over the next decade.

The study showed no evidence that women whose diets contained more soy were less bothered by hot flashes and night sweats than women who ate little soy.

The researchers say very few of the women took soy supplements.

The research examining the impact of soy on hot flashes has been mixed for both soy-rich foods and supplements, says North American Menopause Society (NAMS) Executive Director Margery Gass, MD.

"Typically if something works, even if all the studies don't show it, the majority will," she says. "That is not what we have seen in the soy (and hot flash) studies."

Estrogen, Soy, and Hot Flashes

Soybeans and foods made from them are rich in plant nutrients called phytoestrogens that are believed to act like a weaker version of estrogen.

Estrogen levels naturally drop during menopause. That's thought to trigger hot flashes and night sweats. Some people turn to soy foods and supplements to try to prevent these symptoms.

Asian women who live in countries where soy is a big part of the diet report far fewer hot flashes than women living in Western countries, and one theory has been that their diets protect them.

The new study, which appears in the March issue of the NAMS journal Menopause, included white, African-American, and Asian women in the U.S.

It differed from much of the previous research by excluding women who were already having hot flashes.

"We wanted to see if dietary phytoestrogens could prevent hot flashes in women who were not yet having them," says researcher Ellen Gold, PhD, a professor and chair of the UC Davis department of public health sciences.

This research is very preliminary, and Gold says even though the soy and hot flash studies are inconclusive, there is little downside to eating soy-rich foods or taking soy supplements.

"Many women cannot or won't take hormone therapy," she says. "I don't see anything wrong with taking soy supplements in reasonable doses. If it gives someone relief, ultimately that is what counts."


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SOURCES: Gold, E.B. Menopause, March 2012. Ellen B. Gold, PhD, professor and chair, University of California, Davis department of public health sciences. Margery Gass, MD, executive director, North American Menopause Society.

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