Hrt Interactions

Smoking accelerates hepatic CYP-mediated metabolism of estradiol, lowering circulating estrogen levels and reducing the efficacy of oral hormone replacement therapy for menopausal symptoms and bone protection. It also compounds the venous thromboembolism risk of oral HRT.

Soy isoflavones (genistein, daidzein) act as selective estrogen receptor modulators with preferential binding to ER-beta. Combining high-dose isoflavone supplements with prescribed hormone replacement therapy adds an additional estrogenic signal of uncertain magnitude, which is most concerning for women with a history of estrogen-sensitive cancer.