This article fails to make the distinction between the synthetic hormone progestin and the naturally occurring hormone progesterone. Progestin is medroxyprogesterone acetate (MPA), which is manufactured from the urine of pregnant mares. MPA is 10 to 100 times more potent in its effects on women than natural progesterone and does not produce the same reactions in the body. The terms progestin and progesterone are often used interchangeably, while in fact the differences between the two are biologically significant. Estrogen without opposition from progesterone is still dangerous for women, and at our clinic, we highly recommend that women use natural estrogen in combination with natural progesterone.
Aspen Clinic for Preventive and Environmental Medicine
Dale E. Hammerschmidt
University of Minnesota
San Anselmo, Calif.