Women around the world are searching for something safer than estrogen to get them through menopause. Although Premarin™ is still the most widely prescribed drug in the United States, only 30% of prescriptions are filled. The controversy is obvious—it’s on Time®, Newsweek® and Good Morning America®—women are concerned about avoiding osteoporosis and heart disease, but at the same time they don’t want to increase the risk of getting cancer. The studies that are used to show estrogen’s effectiveness at reducing the incidence of heart disease are extremely controversial due to other important influential factors that tend to be ignored. The studies that show estrogen’s influence on slowing bone loss do not show long term benefit in the years when fractures are more likely. And still other studies show that the use of estrogen is directly and proportionately linked to breast cancer—the longer it is used, the more likely breast cancer will develop. In many European countries, the most widely prescribed forms of estrogen replacement include estriol, the weakest estrogen produced by the body. They also include phyto-estrogens, estrogen-like substances found in certain plants.

These forms of estrogen are intriguing due to their effects on preventing bone loss, controlling hot flashes, and reducing risk of heart disease—yet most American doctors are still largely unaware of them. In terms of cancer promotion, estriol is weaker than estradiol—the more commonly prescribed estrogen in the U.S. Estradiol is used as a replacement hormone in women regardless of breast cancer history. Although conclusive data is lacking, it has been suggested that estriol may even possess cancer-protective benefits similar to those offered by phyto-estrogen containing plants. As a non-patented prescription hormone, estriol is often referred to as a "natural" hormone because it is identical to its counterpart produced by the body—lending itself to be metabolized according to processes that are familiar to the body. Other patented estrogens, which contain estradiol or estrone as their base molecule, are often referred to as "synthetic" due to the fact that proprietary chemical side chains are added to alter the molecule so that it cannot be metabolized in the same way as the body’s own hormones. Although all of these substances are estrogens, they cannot be used interchangeably on a milligram-for-milligram basis; rather, variability in potency must be taken into consideration. Estriol is not the only estrogen available in a natural form, according to Peter R. Holyk, M.D. of Contemporary Health Innovations, PA in Sebastian, FL. "Once deficiencies have been established, the replacement of estriol and estradiol is important." He notes that estradiol does not have to be used in its synthetic form, and that other factors, such as exposure to environmental estrogens, need to be taken into account. Dr. Holyk goes on to suggest that considering only estrogen as a replacement hormone is a limiting approach. "Deficiencies of testosterone, DHEA, Pregnenolone, Progesterone, adrenal hormones and growth hormone can be addressed with natural forms of these hormones. This avoids many of the side effects that are generally associated with HRT (hormone replacement therapy). "When we consider these other hormones, it is clear that men have been largely neglected in HRT and that declining hormones [in men] are important to address as well," said Dr. Holyk.