- Estrogen has been used since the mid-1900s to treat menopausal symptoms in post-menopausal women.

- In addition to treating menopausal symptoms, estrogen replacement therapy has been linked to a number of positive outcomes including reducing the risk of osteoporosis, cardiovascular disease (CVD), dementia/Alzheimer’s, and breast cancer. While there is strong consensus that estrogen is effective for increasing bone strength, the latter three outcomes remain controversial.

- For many decades Premarin – estrogen derived from pregnant horses - was the most common form of estrogen used. Equine estrogen is not the same as human estrogen. Today Premarin is rarely used, having been overtaken by bioidentical estrogen. Premarin has many positive benefits, but it also causes important adverse effects including an increase in blood clots and strokes, complications we do not see with bioidentical estrogen.

- Many medical societies have made official statements that estrogen should not be used for the prevention of chronic disorders such as CVD. These statements are based on older medical studies that primarily used Premarin and not bioidentical estrogen.

- A review of studies that specifically use bioidentical estradiol shows that it causes a substantial reduction in CVD. The degree of improvement is more impressive than that seen with other CVD-lowering medications such as statins.

- This marked reduction in CVD is seen with oral, but not transdermal, forms of bioidentical estrogen.