Premarin, derived from pregnant mare urine, contains at least 10 estrogen forms, including beneficial ones for brain health not found in estradiol or estriol.

“second premarin which is pregnant mayor urine and i say that rubbing your face in it because it sounds so terrible is the longest studied form of estrogen and we now have sixty years of data with premarin and most of the studies that show the benefit for estrogen are studies that were done on premarin for the same reason that joanne manson gave you it's the one that was used most often in addition premarin contains at least 10 different forms of estrogen including some that are the most beneficial forms of estrogen for brain health which is not present in estradiol or estriol”