Myths and truths about bioidentical hormones, from Harvard Women’s Health Watch

"Bioidentical" hormones have often been promoted in the popular press as safer and more effective than FDA-approved hormones. However, there's no good evidence to support this assertion. This is just one of several claims about bioidentical hormones therapy that Harvard Women's Health Watch examines in its September 2011 issue.

The term bioidentical doesn't have an exact medical definition. Health experts generally define bioidentical hormones as compounds that have the same chemical and molecular structure as those produced in the body. Some bioidentical hormones, like natural progesterone (Prometrium) and estradiol products such as Estrace, Vivelle, and Estring are FDA-approved and available by prescription. "Bioidentical" is more broadly defined by advocates of "bioidentical hormone replacement therapy" (BHRT), which includes hormone testing via saliva tests and the use of individually compounded hormones to correct "deficiencies." It's the claims made for BHRT that Harvard Women's Health Watch calls into question. These include: