Data published in the European Journal of Clinical Nutrition indicated that 12 weeks of supplementation led to a 43% reduction in hot flashes, compared to 31% in the placebo group.
Supplementing for an additional 12 weeks led to greater reductions, up to about 70%, wrote the researchers, led by Dr. Mathias Schmidt from Herbresearch Germany.
“Two conclusions can be drawn from the results: (a) even though there was an early effect on hot flushes with soy, the full effect was obviously not yet reached after 12 weeks, as the number of hot flushes still improved during the 12 weeks of open follow-up with soy; and (b) the effect size depends on the severity of symptoms, with better results achieved for higher numbers of daily hot flushes and for a higher severity of symptoms,” they wrote.
Soy for women’s health
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.
The potential of soy to help manage symptoms of the menopause is nothing new, with many previous studies reporting efficacy. For example, a 2012 meta-analysis published in Menopause (Taku et al. Vol. 19, No. 7, pp. 776-90) pooled data from 17 clinical trials, and found that soy isoflavonesmay reduce the frequency of hot flashes by 21%, and reduce the severity of hot flashes by about 26%.
The new study used a commercially available preparation from Alsitan GmbH in Germany that provided 100 mg of total isoflavones per capsule, corresponding to 60 mg of isoflavone aglycones made up of genistein (3.1%), daizein (15.5%), and glycitein (7.7%).
Data from 136 women with at least seven hot flashes per day indicated that hot flashes decreased in both placebo and soy germ extract groups after 12 weeks, with greater reductions in the soy group. The 31% reduction in the placebo group was in line with the researchers’ expectations, but the 43% reduction in the soy group was “lower than anticipated from the general experience with the preparation”.
Both groups were then given soy supplements for a further 12 weeks, after which hot flashes were reduced by 68%.
When the researchers focused on women with “severe” symptoms at the start of the study, the data indicated that hot flashes and sweating were reduced by 71% and 78%, respectively, after the initial 12 week double-blind intervention, compared with 24% for both measures with placebo.
“Overall, the study confirms a modest, but still statistically significant and clinically important efficacy of soy germ extract against menopausal vasomotor symptoms, despite the fact that the study was underpowered due to lower than anticipated group size for hot flushes,” wrote the researchers.
“All studies published to date show that isoflavones are not a miracle cure for hot flushes, with approximately cutting the number of daily hot flushes by half.”
Source: European Journal of Clinical Nutrition
Published online ahead of print, doi: 10.1038/s41430-018-0173-3
“Soy germ extract alleviates menopausal hot flushes: placebo-controlled double-blind trial”
Authors: M. Imhof et al.