Are natural hormones really better?

Until very recently, every woman going through menopause or past it was told she should take hormones. There seemed to be no good reason not to do so; hormones helped women feel better, they were believed to protect their hearts, their bones, and even their brains from the effects of aging. The fact that these hormones came from horses and were very different from human hormones didn’t seem to raise many suspicions. After all, that’s what the doctors were prescribing and what pharmaceutical companies wanted to sell.

A small group of physicians with an interest in nutritional medicine had always favored natural, so-called bio-identical hormones; but at the time few people took notice. These hormones are synthesized from plant materials and – unlike hormones from horses – are identical to hormones produced in the human body. Because they cannot be patented and so cannot be used to make enormous profits, pharmaceutical companies have never had an interest in them.

Twenty years after the fact, we discovered that the old studies about the benefits of hormone replacement were all wrong. New research started to surface and was broadcast everywhere showing that everything that was believed about hormone replacement was incorrect. Not only do hormones not protect women from heart disease, they can cause it – and besides that, they can cause cancer too.

Many of the “natural hormone” doctors felt vindicated and, before they knew it, their practices were booming with women wanting to stop the dangerous horse hormones and replace them with something natural. However, natural does not always mean safe, and there have been no safety studies to date on natural hormones. The doctors’ contention has been that natural hormones must be safe because they are identical to those produced in the human body. A compelling argument, but one that never quite convinced me in the absence of confirming studies.

Now an interesting study from the UK (Environ Health Perspect 112: 1137-1142 (2004)doi: 10.1289/ehp.7028 available from voices that very same suspicion. The study compared growth-promoting effects on uterine tissue of synthetic estrogen, natural estrogen and genistein, a plant estrogen found in soy. If these effects are not substantially different, it is likely that all of these compounds might have the same effect in promoting uterine cancer. The researchers did find that all three compounds acted in a similar manner and they concluded that “the case is yet to be made for regarding synthetic estrogens as presenting a unique human hazard.”

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