Studies are also now appearing that seem to show that HRT reduces the risk of Alzheimer's disease by about 40 to 50 percent. But it is almost certainly synthesized from a naturally occurring steroid molecule, which is chemically manipulated to make the desired hormone. Many medicines are the result of chemical manipulation of naturally occurring molecules. Certainly the yeast that produces it is natural. The PDR states that Premarin, the Prem in Prempro, is made from natural sources.
Medroxyprogesterone is synthesized from chemical precursors.
My next problem stems from the implication of many of the questions that natural is better. The problem I have with many natural products is that we often don't know what the ingredients of the product are, to say nothing about its effectiveness and safety. By and large, such products have never been tested in large well-constructed studies. Their effectiveness stems from hearsay evidence, like testimonials. One person, or an expert, tells someone else that the product made Uncle Jack feel ten years younger.