A comprehensive review of the safety and efficacy of bioidentical hormones for the management of menopause and related health risks

Abstract

Numerous forms of estrogens and progestins are utilized for the treatment of menopausal complaints and associated conditions that occur temporally. Although known to be different with respect to molecular structure, receptor affinity, metabolism, and other physiological traits, most have been treated as if they were clinically identical. The majority of these hormone preparations, commonly referred to as hormone replacement therapy (HRT), should perhaps be more aptly referred to as hormone substitution therapy, as most of the therapies utilized do not exactly match those produced in the body. Research indicates these synthetic hormones vary clinically in safety and efficacy. As such, women and their physicians have, in increasing numbers, been opting for the use of bioidentical hormones; i.e., those that match the structure and function of hormones produced in the body. With greater utilization and research surrounding bioidentical hormones, the differences can now begin to be fully assessed and appreciated. This article reviews the disparities between synthetic and bioidentical estrogens and progestins/ progesterone with respect to safety and efficacy; special attention is devoted to clinical outcomes in the breast, endometrium, bone, cardiovascular system, and brain. The studies reviewed suggest bioidentical progesterone does not have a negative effect on blood lipids or vasculature as do many synthetic progestins, and may carry less risk with respect to breast cancer incidence. Studies of both bioidentical estrogens and progesterone suggest a reduced risk of blood clots compared to nonbioidentical preparations. Bioidentical hormone preparations have demonstrated effectiveness in addressing menopausal symptoms. The author advocates for continued research on bioidentical hormones and concludes there is currently sufficient evidence to support their preferred use over that of their synthetic cousins. (Altern Med Rev 2006;11 (3):208-223)

Introduction

Over the last decade, women and their physicians have in increasing numbers been opting for the use of natural, bioidentical hormones for treatment of symptoms of menopause and to support bone and heart health. (1) The trend away from the use of conventional synthetic hormones, toward those specifically matching the hormones produced in humans (bioidentical) has been driven by several factors, including a global trend toward everything "natural" as seen in the increased interest in organic foods and complementary and alternative medicine (CAM). Perhaps the most significant factor driving the increased interest in bioidentical hormones is the rising fear or suspicion of the "synthetic" hormones used in conventional hormone replacement therapy (HRT). Over the last decade, research-based media reports of risks associated with conventional HRT have prompted women's concerns and altered the approach to hormone use. (2,3) This has been most evident following the results of the U.S. government-sponsored Women's Health Initiative (WHI) study in 2002. The WHI study results led to the conclusion of experts in the field that the risk of using conventional HRT (non-bioidentical hormones), specifically Premarin[R] and Provera[R], outweighed the benefits provided. (4) This report was followed by a significant decline in the use of synthetic hormones at menopause, and a growing number of women and their physicians utilizing and advocating the use of bioidentical hormones. The...