Abstract
Equol is a soy isoflavone metabolite that can be produced by intestinal bacteria. It is lipophilic and resembles natural oestrogens with an affinity to oestrogen receptors. This review is focused on how equol affects breast cancer, as evidenced by in vivo and in vitro studies. Equol is considered chemoprotective in specific endocrine-related pathologies, such as breast cancer, prostate cancer, cardiovascular diseases, and menopausal symptoms. In humans, not everyone can produce equol from gut metabolism. It is postulated that equol producers benefit more than non-equol producers for all the endocrine-related effects. Equol exists in two enantiomers of R-equol and S-equol. Earlier studies, however, did not specify which enantiomer was being used. This review considers equol’s type and concentration variations, pathways affected, and its outcome in in vivo and in vitro studies.
Highlights
Daidzein and genistein are isoflavone phytoestrogen, commonly found in soy foods, such as soy milk, fermented soy or tempeh, miso soup, and tofu [1,2,3]
Studies reporting isoflavones oestrogen receptor binding affinity have classified them as natural selective oestrogen receptor modulators (SERMs) [4]
The emphasis was given to findings associated with equol and its effect on breast cancer that are summarised in the results
Summary
Daidzein and genistein are isoflavone phytoestrogen, commonly found in soy foods, such as soy milk, fermented soy or tempeh, miso soup, and tofu [1,2,3]. Having a similar chemical structure to mammalian oestrogens allows daidzein and genistein to exert oestrogenic effects in humans. Lower daily dietary soy isoflavone of 0.8 mg [5] and 7–9 mg [6] are reported in Finland and UK, respectively, while higher levels of 97 mg were observed in China [7] and 39.5 mg in Japan [8]. Daidzein is metabolised into equol and O-desmethylangolensin (O-DMA) by normal flora of the gut. The variations of gut microflora among individuals resulted in only 30–50% and 80–90% of the population to produce equol and O-DMA, respectively [12]. This interindividual variation leads to inconsistent study outcomes related to the effects of soy in humans
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
