Overturning a Previous Conclusion on HRT
“Every artery in the body, including coronary arteries, contains smooth muscle that is soothed by natural progesterone.”
Back in 1999 when I was perimenopausal and going through a divorce, I experienced chest pain that really got my attention. It radiated into my jaw. And it was associated with loss and grief over finding myself alone after 25 years of companionship. The first chest pain episode was actually triggered by my expectation of having a lovely time with my 16-year-old daughter after picking her up at camp. But instead of the delightful time I longed for, she slept for the entire three-hour drive from camp to home. And then, once home, she leaped out of the car to call her friends. This left me feeling more alone than ever! The heartache was real! That chest pain was angina—resulting from the constriction of the blood vessels around my heart and the subsequent lack of oxygen to my heart muscle. The fact that it first happened during perimenopause when my progesterone levels were at an all time low is not surprising. The hormone progesterone is produced every month by the ovaries following ovulation. It’s a calming hormone that relaxes smooth muscle throughout the body and also has a calming effect on the brain (because it affects the mediators in the brain the same way that valium does!).

Every artery in the body, including coronary arteries, contains smooth muscle that is soothed by natural progesterone—which is in short supply when we start skipping ovulations at perimenopause. This situation sets the stage for angina and chest pain in susceptible women who are producing lots of the stress hormones cortisol and norepinephrine. Stress hormones cause constriction of blood vessels. And these hormones are produced by common things like too much sugar and caffeine, difficult emotions such as anger and grief, or simply lack of sleep.

Progesterone Protects the Heart

As it turns out, women are far more susceptible than men are to nonobstructive coronary artery disease and angina unrelated to exercise. Our coronary arteries are smaller and more prone to constriction. And some of this is hormonal. Even though the large Women’s Health Initiative study (WHI) led the medical profession to believe that hormones were not beneficial for the prevention of coronary artery disease in women, this conclusion is not accurate.

Let me explain. The Women’s Health Initiative was studying the affects of estrogen made from the urine of pregnant horses combined with synthetic progesterone (medroxyprogesterone acetate [MPA], found in Prempro). Though there is much confusion in the medical literature, MPA is not progesterone. And its actions are entirely different. (I predicted this years ago!) Unfortunately, all the large clinical trials that have studied hormone replacement and heart disease have used MPA, not progesterone. However, primate studies have shown that MPA increases coronary artery reactivity while progesterone decreases it. So it’s little wonder that the WHI study and others have shown an increased risk of coronary artery disease using Prempro!

Progesterone also decreases the magnitude and duration of coronary artery constriction. A recent research paper reviewing the cardiovascular effects of MPA versus natural progesterone suggests that there is a minimal level of progesterone necessary for normal cardiovascular function in women.1  For more information on the study, click here.

My clinical experience certainly bears this out. Though a large clinical trial is needed for proof of the cardiovascular benefits of progesterone, smaller studies have shown that angina can be treated effectively by as little as 20 mg of natural progesterone applied to the skin of the chest, hands, or abdomen once or twice per day. Taking progesterone orally doesn’t work nearly as well.

Progesterone and Breast Health

Given the confusion about hormone use, it’s not surprising that so many women are afraid of using any hormone, even a small amount of natural progesterone cream. Here’s what we know about progesterone and breast health:

  • The more pregnancies a woman has, the lower her risk of breast cancer. During pregnancy, a women’s body makes anywhere from 250-600 mg of progesterone per day during the last months. Mother and fetus are exposed to progesterone blood levels of 300-400 ng/ml continuously during the final three months of pregnancy. A non-pregnant woman makes anywhere from 0.1 to 40 mg per day.2  Therefore, if progesterone caused breast cancer many more women would battle with the disease.
  • Progesterone is protective against disease. Women who have elective oophorectomy (removal of ovaries and subsequent lowering of progesterone levels) carry an increased risk of death from stroke, cancer, heart disease, and hip fracture.
  • Progesterone in physiologic doses is not associated with an increased risk of breast cancer. In the only study ever done that has analyzed endogenous levels of progesterone in menopausal women (The Nurses Health Study), Dr. Stacey Missmer and her research partners at the Harvard School of Public Health concluded that progesterone was the only steroid that was not associated with breast cancer.3

There is no question that estrogens of all kinds can increase the risk of breast cancer in susceptible women. And so can MPA. But progesterone in low doses has the opposite effect. After years and years of prescribing low dose progesterone (in the range of 20-60 mg per day on the skin), I feel strongly that the benefits outweigh the theoretical risks.

Progesterone for Your Heart

Heart disease is the leading cause of death in women—and also a prevalent cause of disability. Many women have microvascular disease that causes myocardial ischemia (lack of oxygen to the heart). This situation is a risk factor for everything from loss of energy to dizziness, sleep difficulties, and even sudden death. Though preventive measures such as exercise, supplements, proper diet, stress reduction, and smoking cessation are all important, there is no doubt that a significant number of women would be helped by a small amount of transdermal progesterone.

Perimenopause is the time when a progesterone deficiency is likely to make coronary arteries most susceptible to damage. I urge you to research this issue for yourself. And then, before turning to potentially harmful drugs or synthetic hormones, ask your healthcare practitioner to prescribe transdermal natural progesterone instead.

  1. Hermsmeyer, K., et. al, 2008. Cardiovascular effects of medroxyprogesterone acetate and progesterone: a case of mistaken identity? Nature Clinical Practice: Cardiovascular Medicine, Jul 5(7):387-95.
  2. Cunningham, G., Leveno, K., Bloom, S., et. al., 2005. Williams Obstetrics, 22nd 2005 Edition (McGraw-Hill Professional), Steroid Production Rates in Non-pregnant and Near Term Pregnant Women, p. 70, Table 3-1.
  3. Missmer, S.A., et. al. 2004., Endogenous estrogen, androgen, and progesterone concentrations and breast cancer among postmenopausal women, J Natl Cancer Inst, Dec 15;96(24):1856-65.
Last updated: September 22, 2008