Equol is more estrogenic than daidzein, Lu et al. reported that S-equol could inhibit the growth of LnCaP, DU145 and PC3 human prostate cancer cell lines via upregulating the Forkhead box O3 (FOXO3a) expression, a transcription factor with tumor suppressor functions in PCa. Here, FOXO3 is linked to prostate carcinoma.