Why Is Estriol a Safer Form of Estrogen?
The primary forms of estrogen synthesized by the body include three substances: estrone, estradiol, and estriol. Estrone sulfate is one form of estrogen found in Premarin, while 17-estradiol is the only form of estrogen found in the products Estrace and Estraderm. Estrone and estradiol may significantly increase the risk of breast and ovarian cancer. According to the Merck Manual, conjugated estrogens are substances that have even been listed as known carcinogens. Yet, in the past, these synthetic estrogens were the only estrogens that most traditional medicine physicians prescribed. Estriol, on the other hand, is a weak estrogen that provides many of the anti-aging benefits of estrogen replacement therapy, apparently without the risk of cancer. Consider this evidence that estriol is benign: during pregnancy, huge amounts of estriol are secreted by the placenta to protect the fetus. Urinary assay of estriol is used to assess the viability of the fetus. Since estriol is a weak estrogen,
