Healthnotes Newswire — For many years, the conventional wisdom among doctors has been that estrogen-replacement therapy (ERT) is good for the heart. In fact, the purported protective effect against cardiovascular disease has been one of the main reasons that ERT is so widely recommended for postmenopausal women. However, according to a new report from an American Heart Association (AHA) advisory panel, ERT may not have a positive effect on the heart after all, and may even be harmful in some instances.¹

In reviewing the results of clinical trials, the AHA panel noted that, among women with pre-existing heart disease, ERT did not reduce the risk of new cardiovascular events (e.g., coronary death or nonfatal heart attack). In fact, during the first year of one large study, there were 52% more cardiovascular events in women receiving ERT than in those receiving a placebo. In another study of women without heart disease, administration of ERT was associated with a small increase in the number of heart attacks, strokes, and medically significant blood clots.

The long-held belief that ERT protects the heart has been based almost exclusively on epidemiological or population studies, which have shown a lower incidence of heart disease among estrogen users, compared with nonusers. However, virtually all of the epidemiological studies that address the ERT/heart question suffer from the same flaw: namely, failing to take into account that women who take estrogen also eat healthier food, exercise more often, visit the doctor more frequently for preventive checkups, and generally take better care of themselves than do other women. Therefore, the reduction in heart disease risk associated with ERT might have nothing to do with the estrogen itself. Only so-called “prospective” studies, in which women are randomly assigned to receive ERT or a placebo, can provide a definitive answer. And so far, the results of these prospective studies have not been encouraging.

Thus, the decision whether or not to use ERT should be based on issues other than protection against cardiovascular disease. Beneficial effects of ERT include relief of menopause-related symptoms, prevention of osteoporosis, and possible prevention of Alzheimer’s disease. The most worrisome risk of ERT is a possible increase in the incidence of breast cancer and other hormone-dependent cancers.

The disappointing news about ERT and the heart should spark new interest in the argument made by some doctors that conventional medicine has been using the wrong hormones for ERT.² The vast majority of research in this area has been with conjugated equine estrogens (Premarin®), an extract from the urine of pregnant mares. Horse-urine-derived estrogen has a different chemical structure, and presumably different biological effects, compared with human estrogens. One of the three main human estrogens, estradiol, has been shown to inhibit the oxidation of cholesterol,³ an effect that might be expected to prevent the development of atherosclerosis (hardening of the arteries). Moreover, there is preliminary evidence that estriol, one of the other human estrogens, may have anti-cancer activity.⁴ Additional research is needed to determine how the safety and efficacy of identical-to-natural hormones and horse hormones differ.