Moreover, no negative side effects were reported by the researchers, following the 12-week trial with 147 post-menopausal women and published in Menopause , the journal of the North American Menopause Society.
"What we are trying to find is a safe and effective alternative to hormone therapy," said Blackburn.
"Our study found that patients who consumed the soy supplement showed a reduction in the number of hot flashes."
Isoflavones are well known phytoestrogens - active substances derived from plants that have a weak estrogen-like action.
Isoflavones from soy have been shown to provide a number of health benefits, including the promotion of heart health and the maintenance 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 peri-menopausal women, and have proved to be a popular alternative to hormone replacement therapy for those wishing to control menopause symptoms without resorting to drugs.
The new study, led by George Blackburn, assigned the subjects to receive daily supplements of the daidzein-rich isoflavone-aglycone (DRI) supplement at a dose of either 40 or 60 milligrams, or placebo for 12 weeks.
Nichimo Co. (Tokyo) funded the study and manufactures the DRI ingredient (AglyMax) used in the study.
The isoflavones are reportedly extracted from soy germ fermented with Koji fungus.
At the end of the study, the researchers report that the number of hot flushes in the group receiving the lower dose was reduced by 52 per cent, while the women receiving the higher dose experienced a 51 per cent reduction in the number of hot flushes.
The placebo group reported a 39 per cent reduction in hot flush frequency.
"What we found was that the degree of improvement in women taking the DRI supplement was similar to that of alternative therapies such as a serotonin inhibitor but without their negative side effects," stated co-researcher Hope Ricciotti.
The efficacy of soy isoflavones to ease the symptoms of the menopause like hot flushes remains an area of debate, with both positive and null studies reported.
At the start of 2007 a meta-analysis by researchers from Griffith University School of Medicine, reported positive effects.
"The percentage reduction in flushes was significantly related to the number of baseline flushes per day and the dose of isoflavone studied," wrote the researchers.
However, another recent meta-analysis, published in the Journal of the American Medical Association (Vol. 295, pp. 2057-2071), challenged the benefits and concluded that supplementation with either red clover isoflavones or soy isoflavones produced no reduction in hot flushes.
Demand for soy proteins and other products has been growing rapidly, driven largely by the research showing its health benefits.
Market analysts
The Freedonia Group predict that by 2007 US demand alone for soy products will rise by nearly five per cent each year to $8.23 (€6.7) bn.
Source: Menopause January 2008, Volume 15, Issue 1, Pages 125-134 "Daidzein-rich isoflavone aglycones are potentially effective in reducing hot flashes in menopausal women" Authors: L. Khaodhiar, H. Ricciotti, L. Li, W. Pan, M. Schickel, J. Zhou, G. Blackburn