“The current data are tantalizing enough to suggest that there may for some women be benefits from considering the use of S-equol in menopause, not only for it potential for alleviating [menopause symptoms] but also because of possible other unrelated benefits," said study co-author and scientific director at Rapid Medical Research in Ohio, Wulf Utian.
However, the review pointed to a number of holes in the scientific evidence. Firstly, two of the studies which found evidence in favour of S-equol were observational – rather than clinical – and so ‘meaningful conclusions’ could not be drawn.
“We currently have to rely on … circumstantial data from dietary studies correlating equol-producers with non-producers,” there view said.
The first clinical study involved 134 postmenopausal Japanese women, half of whom were given 20 mg/day of soy isoflavones through dietary intake of soy. The participants included women who naturally produced S-equol and those who didn’t. It found ‘statistically significant decreases’ in symptoms such as anxiety, depression and fatigue.
However, the authors of the review said that the study was limited by the fact that hot flushes were not recorded, although they noted that this may be because hot flushes are not considered a major menopausal symptom in Japanese women.
The only trial that has been conducted on Caucasian women so far found that S-equol supplementation was beneficial in reducing hot flushes, however it crucially lacked a placebo group - although it did include a positive control.
Utian et al. also said it was not certain the effects could be attributed solely to S-equol, as the trials used supplements which contained other potentially active components:
“Only after future studies with pure S-equol will it be possible to determine the exact role of S-equol on menopausal symptoms.”
Concern over adverse effects
The review also draws attention to concerns about possible adverse effects of S-equol.
“Although S-equol is chemically and physiologically different from soybean isoflavones and estradiol, there continues to be controversy about whether isoflavone exposure poses a risk for breast cancer or could be harmful to patients with breast cancer.
“Clinical research published over the past 10 years now shows isoflavone exposure does not adversely affect markers of breast cancer risk.”
On the whole it concluded that findings have been ‘encouraging for the safety of S-equol’.
S-equol is produced when certain types of intestinal bacteria synthesise the bioactive compound daidzein found in foods. However only 50% of Asians and 25% of non-Asians – who in general eat less soy – have the ability to naturally produce S-equol, prompting the industry to look into the market for supplements.
Japanese pharmaceutical company Otsuka developed and patented a proprietary process for converting daidzein to S-equol by fermentating soy germ using the bacterial strain Lactococcus 20-92.
Other possible benefits of S-equol include cardiovascular health and skin health.
Source: Journal of Women’s Health
vol. 24, iss. 3, 2015 DOI: 10.1089/jwh.2014.5006
“S-equol: A Potential Non-hormonal Agent for Menopause-Related Symptom Relief”
Authors: W. H. Utian et al.