Both in vitro and in vivo studies show that black cohosh extracts lack estrogenic effects and don’t raise estrogen levels in the blood. Research on breast cancer cell lines suggests that black cohosh might be safe for menopausal women due to potential anti-estrogenic properties.[1]
Moreover, some studies have shown that black cohosh does not impact gonadotropin or estradiol levels in both healthy women and women with estrogen-dependent conditions like breast cancer. Additionally, black cohosh does not seem to affect levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, prolactin, sex-hormone-binding globulin, and testosterone.[2][3]