Liver metabolites of estradiol are E3, 16alpha-OHE1, 2-OHE2, E1, and two unidentified composition... Over 90% of estradiol is protein bound, mostly by SHBG - Determination of estradiol metabolites in human liver microsome by high performance liquid chromatography-electrochemistry detector.
Some metabolites of E2 are claimed to be carcinogenic, but E3 is a lot safer than estradiol.
Here is the pathway from DHEA to estradiol, estrone, and estriol:
![[Image: attachment.php?aid=8084]](http://www.breastnexus.com/attachment.php?aid=8084)
Aromatase and the liver enzyme 16alpha-OHase are involved in many pathways to estriol.
According to Wikipedia - Estrogen "Though estriol is the most plentiful of the three estrogens it is also the weakest, whereas estradiol is the strongest with a potency of approximately 80 times that of estriol.[unverified]"
Although estriol is weaker, it is more plentiful, and 90% of estradiol is bound to SHBG. So do the math, Estriol is important for NBE. Approximately 10% of estradiol is free. Where as more estriol is free, and is 80 times less potent. Estriol already is about as effective as estradiol, for NBE because it is bioavailable.
10% of estradiol acting 80 times more than estriol. Whereas, let's assume 100% estriol is free, and is 1/80th as strong as estradiol. The free amounts of E2 to E3 become comparable, then.
Some metabolites of E2 are claimed to be carcinogenic, but E3 is a lot safer than estradiol.
Here is the pathway from DHEA to estradiol, estrone, and estriol:
Aromatase and the liver enzyme 16alpha-OHase are involved in many pathways to estriol.
According to Wikipedia - Estrogen "Though estriol is the most plentiful of the three estrogens it is also the weakest, whereas estradiol is the strongest with a potency of approximately 80 times that of estriol.[unverified]"
Although estriol is weaker, it is more plentiful, and 90% of estradiol is bound to SHBG. So do the math, Estriol is important for NBE. Approximately 10% of estradiol is free. Where as more estriol is free, and is 80 times less potent. Estriol already is about as effective as estradiol, for NBE because it is bioavailable.
10% of estradiol acting 80 times more than estriol. Whereas, let's assume 100% estriol is free, and is 1/80th as strong as estradiol. The free amounts of E2 to E3 become comparable, then.