Perhaps you’ve awakened from a dead sleep “on fire” and drenched in sweat. Or maybe in the middle of an important meeting you’ve suddenly felt your face flushing and the room closing in. No matter where or how you’ve experienced a menopausal “hot flash,” the sensations are not pleasant.

A study published recently by Menopause: The Journal of The North American Menopause Society (doi: 10.1097/gme.0b013e3182410159) says relief may be as close as your local health food store. A meta-analysis of studies on the role of soy isoflavones in alleviating hot flashes found clear and consistent evidence that soy isoflavone supplements are significantly more effective than a placebo in reducing their frequency and severity.

“The key finding in this study is that when you limit the analysis to isoflavone supplements derived from soy or those with profiles identical to soy, there is a very consistent effect on hot flash relief,” said Mindy S. Kurzer, PhD, professor of nutrition at the University of Minnesota, hormone expert and contributing author to the study. “Almost all studies in the meta-analysis show a consistent reduction in hot flash frequency and severity,” she said in a press release about the findings.

The meta-analysis indicated that

  • ingestion of soy isoflavones for 6 weeks to 12 months significantly reduced the frequency of hot flashes by more than 20% compared with a placebo;
  • soy isoflavones significantly reduced hot-flash severity by more than 26% compared with a placebo;
  • the decrease in hot-flash frequency in longer-duration trials (more than 12 weeks) was approximately threefold greater than the decrease in shorter-duration trials.

“For women who are bothered by hot flashes, any reduction in frequency or severity may be welcome—especially if it can be achieved without side effects,” said Melissa K. Melby, PhD (University of Delaware), hot-flash expert and contributing author to the study. “Soy isoflavones appear to be a good first approach to alleviating hot flashes. Since there is often a large placebo effect, women taking supplements with the right soy isoflavone profile will likely see at least a 50% reduction compared to doing nothing,” she said in the PR Newswire press release.

Though multiple isoflavones exist in nature, the three found in soy are genistein, daidzein and glycitein. According to the researchers, isoflavone supplements providing higher amounts of genistein were approximately 50%–200% more potent in reducing hot-flash frequency than isoflavone supplements containing lower amounts of genistein.