What Is the Scientific Evidence for Progesterone?
Despite widespread reporting that true progesterone is effective for treating or preventing osteoporosis, the evidence for such an effect is at best inconsistent. This notion began with test tube and other preliminary studies suggesting that progesterone or progestins can stimulate the activity of cells that build bone. 10,11 Subsequently, a poorly designed and uncontrolled study (really, a series of case histories from one physician’s practice) purportedly demonstrated that progesterone cream can slow or even reverse osteoporosis. 12-14 However, a 1-year, double-blind trial of 102 women given either progesterone cream (providing 20 mg progesterone daily) or placebo cream, along with calcium and multivitamins, found no evidence of any improvements in bone density attributable to progesterone. 15 A smaller, short-term trial found that progesterone cream has no effect on bone metabolism. 20 In contrast to these negative results, benefits were seen in a small 2-year, double-blind, placebo
