Researchers pooled results from 19 published studies involving 1,200 women comparing soy supplements to a placebo for the treatment of hot flashes and determined that soy supplements with higher amounts of the isoflavone genistein were 200 percent more effective for reducing hot flash frequency than supplements that contained lower amounts, reports WebMD. The studies ranged in duration from six weeks to one year, and researches found that the positive effects of soy were greater in the longer studies.
Researchers looked at studies testing the efficacy of soy for treating hot flashes published through 2010, explains WebMD. The women in the 19 studies lived in the United States and nine other countries. A Chinese study published in the journal Menopause showed that 40 percent of the 90 participating women using soy germ isoflavones experienced a reduction in hot flashes, adds Healthline. Twenty-nine percent of the women who received placebos reported a reduction.
These studies involved the use of soy supplements, but many experts believe that consuming soybean-derived foods and beverages is more advantageous, notes WebMD. Two servings daily of soy milk, tofu, tempeh or edamame are recommended for women hoping to treat hot flashes and other menopausal symptoms without the use of hormone replacement therapy. As of 2015, researchers disagree about the universality of soy’s positive effect on hot flashes in women, pointing to the variations in methodology and preparations used in the studies to date. However, most experts agree that adding dietary soy products or supplements to a woman’s protocol to relieve menopausal symptoms is a viable first line of treatment.