As little as two daily servings of soy can reduce the frequency and severity of hot flashes in menopausal women, a sweeping new analysis of women’s health studies has found.
In what scientists say is the most comprehensive study yet to examine the effects of soy on menopause, researchers who reviewed 19 previous studies involving 1,200 women found soy can alleviate hot flashes by up to 26 percent.
The findings, published in Menopause: The Journal of the North American Menopause Association, indicated chemicals in soy known as isoflavones exert a mild estrogen-like effect to ease menopausal symptoms.
Lead resarcher Melissa Melby, with the University of Delaware, said the interest in soy and menopause stems was prompted by studies of Japanese women that low frequency of hot flashes to the high soy consumption that often begins in utero and continues throughout their lifespan.
"Soy is probably more effective in these women," Melby said. "But if you're 50 and you've never touched soy, it's not too late. We've found that it still helps."
According to the new study’s findings:
• Ingesting at least 54 milligrams of soy isoflavones daily for six weeks to a year reduces menopause hot flash frequency by 20.6 percent and severity by 26 percent, compared to a placebo.
• Women who consumed soy isoflavones for 12 weeks were three times less likely to have hot flashes.
• Isoflavone supplements with higher levels (at least 19 milligrams) of genistein, one of the two main types of isoflavones, were twice as effective at reducing hot flash frequency than lower amounts.
A gram of soy protein in soybeans and traditional soyfoods provides approximately 3.5 milligrams of isoflavones. Two 8-ounce glasses of soymilk or seven ounces of tofu provide approximately 50 mg of isoflavones.