Hi Susi, welcome and thanks for your question.  Fosteum ingredients are: zinc, D3 and genistein (isolated from soy).  Since it has genistein they list the effects of that which can be somewhat similar to HRT even though that isn't in it.  Genistein is a isoflavone isolated from soy and some isoflavones act like a phytoestrogen (hormone from plants) in mammals.   If you are allergic to soy you wouldn't be able to take this.  Did you read the article on Fosteum?  It should explain the connection between isoflavones, soy, and phytoestrogens.  Here's the link on the article that also has the clinical trial done on it.  Read through the comments since the first study listed was moved and the new URL is in the last comment.   Hope this helps, and good luck.