My sister had a hystorectomy several years ago and has been taking no estrogen due to it causing cancer. Well now her bones are in terrible shape! A very minor accident from walking cause her to have 5 broken bones, some of which shattered. We realize that she will need some sort of estrogen but we don't want to trade one disease for another. What is the best natural estrogen that you know of? And what can she do, naturally, to build bone density quckly? She is not even 40 yet! Thanks much!!