In a recent article, I explained the benefits of bioidentical hormone replacement (BHRT) for women. I will briefly summarize those benefits here and you can get more detail from my website

Women who take bioidentical hormone replacement feel more energy and vitality while losing weight. Bioidentical hormones are the same ones that your body produces including estrogen and progesterone. With BHRT, women have improved mood and sleep better. Sexual health is also revitalized with increased libido. Those benefits are accompanied by overall improvement of health. Women who take estrogen are much less likely to get heart disease with the risk of heart disease cut in half with estrogen. Also, estrogen actually increases bone density decreasing the risk of osteoporosis and accompanying fractures. This is especially important because of the high risk of death after a hip fracture. Estrogen also is protective against Alzheimer’s disease, especially when starting hormone replacement in the early years of menopause. Women who take estrogen for more than 10 years have significantly reduced incidence of dementia. So heart disease, osteoporosis and dementia , which are the 3 leading causes of death in women over 70 are all greatly reduced with hormone replacement.

So with all of these benefits, why are so many women apprehensive about taking hormone replacement? The most common reason given is a fear of breast cancer and I will address this. The 2 most commonly prescribed hormones for menopause are Premarin and Provera, sometimes taken as a combination pill, PremPro. Premarin is horse-derived estrogen whose name is a truncation of ‘pregnant mare’s urine’. Premarin provides some of the benefits of estrogen including improved bone density but comes at a cost – there is a dislodging of clots so those who have plaque build-up in their arteries are predisposed to a blood clot or even stroke. However, estradiol, which is a bioidentical estrogen, has not been shown to dislodge clots so does not have this same risk.

The other hormone commonly prescribed is Provera, a synthetic version of progesterone. Unfortunately, this synthetic version has the opposite effects of the beneficial progesterone. For example, progesterone is protective against heart disease while Provera negates some of estrogen’s cardiac benefit. Progesterone has positive effects of mood while Provera causes irritability and anxiety.

Even more concerning, Provera has been shown to increase the risk of breast cancer. The WHI study published in 2004 is the largest controlled study of hormone replacement to date. Unfortunately, the hormones tested were Premarin and Provera. There were 2 treatment groups, one taking Premarin alone and one taking Premarin and Provera. Taking Premarin alone did not increase the risk of breast cancer. However, when taking the combination of Premarin and Provera, there was a 30% increased risk of breast cancer, suggesting that Provera causes breast cancer. With estrogen alone, several meta-analyses have shown a relative risk of 1.0, or in other words, no increased risk of breast cancer.

On the other hand, bioidentical progesterone protects against breast cancer. In the lab, progesterone has been shown to inhibit breast epithelial cell proliferation. In a study in the American Journal of Epidemiology, it was noted that breast cancer risk was 50 times greater and 10 fold increase in deaths in those with low progesterone levels. Progesterone has anti-proliferative effects on cancer cells inducing apoptosis (cell death) of cancer cells. Synthetic Provera blocks the progesterone receptor sites and breast proliferation occurs with no down regulation to oppose this. Yet many confuse the two and think Provera is progesterone, incorrectly concluding that progesterone is harmful.

With regard to breast cancer, the conclusion is that estrogen does not increase the risk of breast cancer. Bioidentical progesterone protects against breast cancer while synthetic Provera increases risk of breast cancer by 30%. Similarly, progesterone protects uterine tissue. Unopposed estrogen causes proliferation of uterine tissue, which increases the risk of uterine cancer. Fortunately, progesterone protects uterine tissue so when taking combination of bioidentical estrogen and progesterone, there is no increased risk of uterine cancer. An example of this is when women take tamoxifen for breast cancer, there is increased risk of uterine cancer because the tamoxifen, which has estrogen-like effects, thus stimulating uterine tissue. Taking progesterone would be protective of the uterus. Similarly, those with PCOS (polycystic ovarian syndrome, which I will be discussing in an upcoming issue), have unopposed estrogen stimulation of uterine tissue and they should be taking progesterone to protect the uterus. It is very important to take oral progesterone rather than using a progesterone cream so the protective levels of progesterone can be reached. Thus, the beneficial effects of hormones are achieved while the breast and uterus are protected.

So by taking bioidentical hormones there is no increased risk of cancer while there are many health benefits including better heart health, better bone health, better brain health and overall feeling great while losing weight. Understanding the literature and the distinction between synthetic and bioidentical hormones is key to understanding the risks and benefits. To learn more, you can check out my website, On my home page is a podcast that goes into more details about hormone replacement.