L ife Extension magazine has previously suggested alternative approaches for women who are afraid of the cancer risks or side effects of long-term therapy with estrogen drugs approved by the Food and Drug Administration, such as Premarin. Here, we discuss an intriguing alternative called estriol, which is used extensively in Europe for estrogen replacement therapy in menopausal and post-menopausal women, but to date has rarely been used for that purpose in the United States. First, some background. The primary forms of estrogen include three substances-estrone, estradiol and estriol. Estrone sulphate is the form of estrogen found in Premarin, while 17-b estradiol is the form of estrogen found in the products Estrace and Estraderm.
Estrone is the oxidized form of estradiol.
Both of these substances, however, are the estrogens that significantly increase the risk of breast and ovarian cancer when taken for more than 10 years. According to the Merck Manual, conjugated estrogens are substances that even have been listed as known carcinogens. Estriol, on the other hand, is a weak estrogen that provides the anti-aging benefits of estrogen replacement therapy, apparently without the risk of cancer. Urinary assay of estriol is used to assess the fetus' viability. Since estriol is a weak estrogen, larger amounts must be used for estrogen replacement therapy.