PARENT ESTROGENS (Estradiol-E2, Estrone-E1, Estriol-E3)
Estriol is considered a safer estrogen because it cannot be converted to more toxic catechol estrogens or down-stream quinones that damage DNA, causing mutations that increase breast cancer risk.
The ratio of potentially toxic urinary estrogens (i.e. 2- and 4-catechols of estradiol and estrone) to inert estriol has been used for many years as an index of breast cancer risk.
The E3/E2+ E1 ratio originally was based on Professor Henry Lemon's hypothesis [Lemon H. Cancer, 25-2, 423-435, 1970 (L)].
According to Lemon, the more estriol in urine, relative to estradiol and estrone, the lower the breast cancer risk.
Clinically, Lemon found that Japanese women, who have less breast cancer than women in the US, also have higher E3/E2+E1 ratios.
Higher levels of estrogens such as E2 and E1 are common in women approaching menopause (perimenopause) due to increasing levels of gonadotropins (LH and FSH) and lower progesterone. During the menopausal transition (peri-menopause with irregular menstrual cycles that occur usually from about age 45-55, but earlier in some women) estrogens are more likely to fluctuate erratically from high to low in the absence of progesterone, precipitating symptoms of both estrogen excess (dominance) and deficiency.
Consider means to maintain estrogens within healthy physiological range through diet (eating more vegetables, fruits, and grains with fiber), gentle exercise programs, stress reduction techniques, nutritional supplements, and use of natural progesterone as this helps accelerate estrogen clearance and balance symptoms of estrogen excess.
E3/(E1+E2)
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