Soy has long been mooted as an ingredient for easing the symptoms of the menopause.
Now in the most comprehensive study to date, researchers have found that two daily servings of soy can reduce the frequency and severity of hot flashes by up to 26 percent compared to a placebo.
Make it soy: Drinking two glasses of soya milk a day for more than six weeks reduced hot flush symptoms up to 26 per cent
A team from the University of Delaware reviewed 19 previous studies that examined the effect of the protein source on more than 1,200 women.
The effectiveness of soy in alleviating hot flushes has up to now been inconclusive, with some studies suggesting soy to be beneficial and others suggesting otherwise.
The authors of the latest study argue much of the discrepancy is due to small sample sizes and inconsistent methodology, according to the authors.
'When you combine them all, we've found the overall effect is still positive,' said study author Melissa Melby.
Soy protein comes from soybeans - a legume native to East Asia. Two glasses of soya milk or seven ounces of tofu provide approximately 50mg of isoflavones, which appear to provide the beneficial effect.
The team found ingesting at least 54mg of soy isoflavones daily for six weeks to a year reduces menopause hot flush frequency by 20.6 per cent and severity by 26 per cent, compared to a placebo.
The authors added that women who took soy for more than 12 weeks saw a threefold greater drop in hot flushes compared to those in shorter trials.
The studies also revealed that isoflavone supplements with higher levels (at least 19mg) of the genistein type, were more than twice as effective.
Prof Melby said this was particularly notable because the compound is the primary isoflavone in soybeans and soy foods.
'Eating soy foods, or using supplements derived from whole soybeans, may work better for women,' she said.
Soy first became of interest as a treatment for the menopause after scientists observed Japanese women - who ate soy all their lives - experienced fewer hot flushes.
'Soy is probably more effective in these women. But if you're 50 and you've never touched soy, it's not too late. We've found that it still helps,' said Prof Melby.
The findings were published in Menopause: The Journal of the North American Menopause Association.
Read more: http://www.dailymail.co.uk/health/article-2125511/Drinking-soy-milk-twice-day-CAN-reduce-hot-flushes.html#ixzz1rBCzgyyZ