Isoflavones from soy may reduce the frequency of hot flashes by 21%, according to a meta-analysis of 17 clinical trials.
The analysis also revealed that soy isoflavones were effective in reducing the severity of hot flashes by about 26%. «Soy isoflavones appear to be a good first approach to alleviating hot flashes. Since tehre is often a large placebo effect, women taking supplements with the right soy isoflavone profile will likely see at least a 50 percent reduction compared to doing nothing,» said study co-author.
Isoflavones are well known phytoestrogens – active substances derived from plants that have a weak strogen-like action. Isoflavones from soy have been shown to provide a number of health benefits, including the promotion of heart health and the maintenace of bone health in post-menopausal women.
They have also been studied for their role in cancer prevention and slowing down the ageing process in perimenopausal women, and have proved to be a popular alternative to hormone replacement therapy for those whishing to control menopause symptoms without resorting to drugs.
The new meta-analysis provides strong support for the efficacy of soy isoflavones to reduce the frequency and severity of hot flashes.
The analysis revealed that an average intake of 54 milligrams per day of soy isoflavones for between 6 weeks and 12 months was associated with an average 21% reduction in the frequency of hot flashes, compared with placebo.
In addition, this dose and duration was associated with a reduction in the severity of hot flashes by 26%, compared with placebo.
In terms of the specifc isoflavones, supplements that provided at least 18.8 mg of genistein «were more than twice as potent at reducing hot flash frequency than lower genistein supplements», said the reviewers.
«Supplements providing a total of 50 mg of total isoflavones will be effective as long as they also provide at least 19 milligrams of genistein.»