For those who want to avoid estrogens in any form, phytoestrogens from plants are a consideration. A soy extract that provides at least 50 mg of soy phytoestrogens are often a key ingredient for effective natural estrogen replacement therapy. Based upon records of dietary soy consumption inJapan, where breast cancer incidence is very low, daily soy isoflavone intake has been estimated at 50 mg per day. The typical Western diet, on the other hand, only provides 1 to 5 mg a day of the soy isoflavones that may protect against several forms of cancer.
In premenopausal women the majority of estrogen produced by the body is estradiol (produced primarily in the ovaries), while in postmenopausal women estrone (produced in fat cells) is the type of estrogen present in the greatest amount; however, the body is able to convert one type of estrogen into another to a certain extent. Because of the limited research into potency, delivery methods and conversion of the various estrogens, a valid scientific understanding of compounded estrogen products has not been achieved.  Synthetic estradiol, taken orally, splits when absorbed in the gastrointestinal tract and delivers bioidentical estradiol to the bloodstream.