A review of studies on soy isoflavones indicates that they can have a very consistent effect on hot flashes.
A meta-analysis of 17 separate studies* found evidence that soy isoflavone supplements significantly reduce the frequency and severity of menopausal hot flashes.
The meta-analysis – the largest and most comprehensive conducted to date – showed that taking soy isoflavones for six weeks to 12 months reduced the frequency of hot flashes by more than 20 percent, and reduced the severity of hot flashes by more than 26 percent.
How long women took soy also appeared to make a difference, with trials lasting longer than 12 weeks showing a three times greater decrease in hot flashes than shorter trials.
The type of soy isoflavone is also important. Isoflavone supplements providing higher amounts of genistein were approximately 50 to 200 percent more potent at reducing hot flash frequency than isoflavone supplements containing lower amounts of genistein.
“Soy isoflavones appear to be a good first approach to alleviating hot flashes,” said a contributing author of the study. “Almost all studies in the meta-analysis show a consistent reduction in hot flash frequency and severity.”
*Menopause (New York, N.Y.). 03/2012; “Extracted or synthesized soybean isoflavones reduce menopausal hot flash frequency and severity: systematic review and meta-analysis of randomized controlled trials.” Kyoko Taku, Melissa K Melby, Fredi Kronenberg, Mindy S Kurzer, Mark Messina