Soy Isoflavones Linked With Decreased Hot Flashes, Review Finds

Consuming two servings of soy a day may help to ease hot flashes from menopause, according to a new review of studies.

Researchers from the University of Delaware analyzed the results of 19 studies, which included 1,200 women, and found that soy isoflavones are linked with a decrease in hot flash severity. Their study was published in Menopause: The Journal of the North American Menopause Association.

Women who consumed 54 milligrams of soy isoflavones -- which are found in soy, and are estrogen-like -- each day for anywhere from six months to a year experienced a 20.6 percent decrease in the frequency of their hot flashes, and a 26 percent decrease in the severity of their hot flashes.

For comparison, two 16-ounce glasses of soy milk or 7 ounces of tofu contain 50 milligrams of soy isoflavones, the researchers noted.

In particular, researchers found that supplements with at least 19 milligrams of genistein -- a kind of isoflavone -- seemed to be more effective at decreasing the number of hot flashes the women had.

Genistein is found in soybeans and soy foods, so researchers noted that eating those foods instead of taking supplements could be a way for women to get that particular isoflavone.

The role of soy in easing menopausal symptoms has long been debated, mainly because many studies on the subject haven't produced clear-cut results. However, the researchers said that the reason for the inconclusive results is because scientists may be inconsistent in how they conduct the studies, or the sample sizes are too small.

But “when you combine them all, we’ve found the overall effect is still positive,” study researcher Melissa Melby, a medical anthropology professor at the University of Delaware, said in a statement.