Are natural alternatives to estrogen replacement therapy safe?

Although individuals often consume natural products because of their potential health benefits, a new review indicates that it is not clear whether the benefits of plant-derived compounds that mimic estrogen outweigh the possible health risks. The findings are published in the British Journal of Pharmacology.

Phytoestrogens are compounds from plants that are similar in structure to estrogen and are found in a variety of foods, especially soy. Some women may consume phytoestrogens promoted as natural alternatives to hormone replacement therapy to help ease menopausal symptoms such as hot flushes or to protect against bone loss.

When Ivonne Rietjens, PhD, of Wageningen University in The Netherlands, and her colleagues analyzed the published medical literature, they found that several potential health benefits of phytoestrogens have been reported, including lowered risks of cardiovascular disease, obesity, metabolic syndrome and type 2 diabetes, brain function disorders, and various types of cancer, in addition to reduced menopausal symptoms. Phytoestrogens are considered endocrine disruptors, however, which indicates that they have the potential to cause negative health effects, including infertility and increased risks of cancer in estrogen-sensitive organs such as the breast and uterus.

Given the data on potential negative health effects, the review's authors conclude that the current evidence on phytoestrogens' beneficial effects is not so obvious that they clearly outweigh the possible health risks. "This implies that a definite conclusion on the health effects of phytoestrogens, positive or negative, cannot be made," said Prof. Rietjens. It may be that the question of whether phytoestrogens are beneficial or harmful has different answers dependent on individuals' age, health status, and even the presence or absence of specific gut bacteria. Additional studies are needed to provide clarity.