Synthetic vs. Natural Progesterone: THE VERDICT IS IN!

I attended a short “informative seminar” with a fairly new OB/GYN who had been out of medical school for about a year. The physician was to supply the latest information about hormone replacement therapy (HRT), but what I heard were the same stories that I heard 20 years ago about synthetic hormones.

Obviously, big pharmaceutical companies are still contributing greatly to our medical schools. What most physicians do not realize is that, in this country, a natural product cannot be patented and, therefore, pharmaceutical companies will not fund a study that includes natural products. Most of the studies done with natural products are in foreign countries and given scientific processes are the same. In four different studies, synthetic progestins and progesterone have a number of differences in their molecular and pharmacologic effects on breast tissue, as some of the procarcinogenic effects of synthetic progestins contrast with the anticarcinogenic properties of progesterone.

When discussing progesterone, it is important to understand the difference between natural progesterone and the synthetic progesterone analogs called progestins. Progestogens is an umbrella term for both natural progesterone and the synthetic progestins, because they all have progestational effects in the uterus. One of the most common progestins, medroxyprogesterone acetate (Provera®), has been linked to blood clots, fluid retention, acne, rashes, weight gain, and depression. Progestins are also able to bind to glucocorticoid, androgen, and mineralocorticoid receptors, which explains the wide range of side effects many women experience while taking progestins. Synthetic progestins may also increase the conversion of weaker endogenous (naturally occurring) estrogens into more potent estrogens. The vast majority of research studies have been conducted using progestins rather than natural progesterone, which explains the disparity and negativity of the results.

Restoring the body’s supply of natural progesterone confers multiple health benefits, including balancing blood sugar levels, promoting normal sleep, reducing anxiety, and stimulating new bone growth. Progesterone’s many functions in the body include:

  • maintaining the uterine lining and preventing excess tissue buildup
  • inhibiting breast tissue overgrowth
  • increasing metabolism and promoting weight loss
  • balancing blood sugar levels
  • acting as a natural diuretic
  • normalizing blood clotting
  • stimulating the production of new bone
  • enhancing the action of thyroid hormones
  • alleviating depression and reducing anxiety
  • promoting normal sleep patterns
  • preventing cyclical migraines
  • restoring proper cell oxygen levels
  • improving libido

Controlled studies and most observational studies published in the last five years suggest that the addition of progestins (synthetic progesterone) to hormone replacement therapy, particularly in a continuous combined regimen, increases the risk of breast cancer compared to estrogen alone. While the results of clinical trials may accurately assess the risks associated with synthetic progestin compounds and estrogen/progestin combinations, the data do not reflect what might have been the result had natural progesterone been used instead of synthetic progesterone.

Recent studies suggest that the addition of natural progesterone in a cyclic manner does not increase breast cancer risk. These findings are consistent with in-vivo data suggesting that progesterone does not have a detrimental effect on breast tissue. Nature has given progesterone to men and women alike to balance and offset the powerful effects of estrogen. Some of the most common concerns of aging women are weight gain, insomnia, anxiety, depression, and migraine. For other women, even more debilitating conditions such as cancer, uterine fibroids, ovarian cysts, and osteoporosis now play a predominant role in their lives. As men age, complaints of weight gain, loss of libido, and prostate enlargement top their list of health concerns. Many physicians and scientists are becoming more aware of a common link between these symptoms and conditions. That common link is often an imbalance between two sex hormones, progesterone and estrogen.

The brain is highly responsive to progesterone. In fact, progesterone concentrations in the brain have been shown to be 20 times higher than in the blood. Insomnia, anxiety, and migraine are just a few of the conditions linked to an imbalance of progesterone and estrogen. In the brain as elsewhere in the body, progesterone counterbalances the effects of estrogen. Whereas estrogen has an excitatory effect on the brain, progesterone’s effect is calming. Clinical and anecdotal experience indicates that women with estrogen dominance sleep restlessly, whereas progesterone replenishment enhances sleep.

Most controlled studies and observational studies in the past five years suggest that the addition of synthetic progestins to synthetic estrogen in hormone replacement therapy, particularly in a continuous combined regimen, increases breast cancer risk compared to synthetic estrogen alone. By contrast, recent studies suggest that the addition of natural progesterone does not affect breast cancer risk. In fact, a large base of evidence suggests that progesterone is a protective agent against, as well as a potential adjunctive treatment for, breast and endometrial cancers. Whereas estrogen is pro-proliferative, causing the cells in the breast and uterus to multiply, progesterone does not promote proliferation of these tissues.

One of the most significant studies of the relationship between low levels of natural progesterone and increased breast cancer risk was published in the American Journal of Epidemiology in 1981. The study followed 1,083 women with a history of difficulty becoming pregnant for periods ranging from 13 to 33 years. The researchers found that infertile women who demonstrated a progesterone deficiency had a premenopausal breast cancer risk that was 540% greater than that of women whose infertility was due to non-hormonal causes. Furthermore, the women with a progesterone deficiency had a 1,000% greater chance of death from all types of cancer.

In a study conducted at the National Taiwan University Hospital, researchers showed that transdermal estradiol increased breast cell proliferation by 230%, while transdermal progesterone decreased cell proliferation by over 400%.

Many medical professionals believe that once the uterus has been removed, there is no need to supplement with progesterone. Clinical experience and a review of the scientific literature, however, make it is clear that unopposed estrogen therapy can lead to many undesirable health conditions. When women are young, they have optimal levels of all the steroid hormones, not just estrogen. Replacing only estrogen after a complete hysterectomy is a sure-fire way to increase existing estrogen dominance. Whether a woman has a uterus or not, research suggests that estrogen replacement therapy should not be given without natural progesterone.

Typically thought of as a female hormone, progesterone can also be an invaluable tool in hormone modulation in men. Benign prostatic hyperplasia seems to be related to long-term exposure of the prostate gland to the strong androgen dihydrotestosterone and possibly to estrogens. In fact, the late Dr. John R. Lee, considered a pioneer in natural progesterone therapy, believed that excessive exposure to estrogen was a primary cause of prostate enlargement and prostate cancer. In addition to counterbalancing the negative aspects of estrogen, progesterone may also inhibit 5-alpha-reductase, the enzyme that converts testosterone to dihydrotestosterone.

If you have any concerns of your own, don’t hesitate to call us at Texas Star Pharmacy. We have a wonderful staff and a certified clinical nutritionist at your service. We always love to hear from you.

To make an appointment with Texas Star Pharmacy’s specialized staff, please call 972-519-8475