symptoms of menopause: The term synthetic is also used incorrectly in two ways: to refer to the process used to manufacture all estrogens, including bioidentical estrogens, and to compounds that interact with estrogen receptors similarly to estrogen molecules but are not found in nature. Examples of the latter two include diethylstilbestrol and ethinylestradiol. Uses BHT is used to reduce the symptoms of menopause. It is also promoted by some practitioners for anti-aging purposes providing benefits beyond menopausal symptom relief, such as improving quality of life, though there is little evidence to support these claims. Components and compounding Compounded preparations of bioidentical hormones usually include estriol, estrone, estradiol, testosterone, progesterone, and sometimes dehydroepiandrosterone (DHEA), either individually or combined. They are promoted as natural, safer and (in some cases) more efficacious than CHT; however, there are no scientific studies to support claims of superiority of BHT over CHRT. Estimates from sales of bulk hormones for compounding suggest that more than one million women may be using compounded BHT in the United States. Bioidentical hormones are expected to have the same risks as conventional hormones made with the same categories of hormones. Estrogens 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 primary estrogen present; 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, decomposes when absorbed in the gastrointestinal tract and delivers bioidentical estradiol to the bloodstream. The hormone estriol, produced during pregnancy, is frequently compounded into bioidentical preparations in the United States. While some think it to be a weaker estrogen, with a more limited period of effectiveness than estradiol, it has been demonstrated to be a stronger estrogen in certain ways. Though initial research in the 1970s suggested possible use, follow-up studies have failed to confirm this potential. Estriol is not found in any FDA-approved drug, and its safety and effectiveness as a hormone supplement is unknown. Estriol was part of the United States Pharmacopeia before FDA approval was needed for its use. Its approval was grandfathered in by the FDA until 2008 when the agency banned its use,