As mentioned earlier, equol has the ability to bind ERβ. This may explain how isoflavones accumulate in prostate tissue and prostatic fluid after oral supplementation [
19,
20,
21] and it has been shown that binding ERβ in the prostate decreases inflammation and carcinogenesis [
22]. Furthermore, this not only applies to prostate health but to other tissue-specific sites in the body where ERβ is present. For example, there is an abundance of ERβ in the brain, specifically in the frontal cortex and raphe nuclei as well as other brain regions that may be involved in mechanisms of anxiety and depression [
23,
24,
25]. Preliminary data from our laboratory suggest that equol treatment in aged-rats after natural ovarian failure is effective as an anti-depressive agent at low concentrations that significantly increase serotonin levels. Additionally, the skin represents the largest organ of the body where ERβ is abundant in the epidermal and dermal regions, especially the keratinocytes and fibroblasts, respectively which may be tissue sites for beneficial alterations in androgen hormone action [
26]. For instance, it is known the androgens decrease, whereas, estrogenic compounds enhance wound healing [
27] that may have effective applications for topical treatments.
