To protect the uterine lining from continuous stimulation by estrogen, most physicians prescribing standard ERT combine it with Provera®. If you ask them if it is progesterone, they’ll probably even tell you it is—it is not. It is medroxyprogesterone acetate, which is natural progesterone altered by the addition of a molecule to make it patentable and more orally absorbable. This molecule alters Provera’s effect on tissues other than the uterus.

Many women discontinue ERT because they don’t like the way it makes them feel—irritable and often depressed. In contrast, bioidentical micronized progesterone is often called the feel-good hormone because it elevates mood and is calming. Women who have experienced mood swings and migraine headaches on Provera often notice complete resolution of these symptoms when switched to bioidentical progesterone. In addition, bioidentical progesterone was found to have the best effect on HDL cholesterol in the PEPI trial. This trial is the largest to date to include bioidentical micronized progesterone. Bioidentical progesterone can also act as a natural diuretic, in contrast to Provera® which often causes fluid retention and bloating.

There is, however, an even more compelling reason to avoid using Provera. It comes from recent studies by a number of different researchers, and thus is unlikely to be disproved. These researchers showed that Provera can reverse by 50% the coronary artery-dilating effect of estrogens and that progesterone does not have this negative effect. .