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Progesterone FAQ

Estrogen Is Not The Only Hormone: The Important Role Of Progesterone

Following are some Frequently Asked Questions regarding progesterone, one of the two primary female hormones (the other being estrogen).

  1. What is progesterone?
  2. What is progesterone's relationship to estrogen?
  3. What are some of the functions of endogenous progesterone in the human female?
  4. What is "estrogen dominance" and what is its relationship to progesterone?
  5. What are some external factors which may contribute to estrogen dominance or hormone imbalance?
  6. How long will I produce progesterone in my lifetime?
  7. What can I do to replace my declining progesterone level?
  8. If I've had a hysterectomy and my doctor has prescribed estrogen, do I need to take progesterone to maintain hormone balance?
  9. If progesterone is such an important hormone, why doesn't my doctor know about it or prescribe it?

While reading Project AWARE's FAQ, it is important for the reader to keep in mind that what doctors know and accept about progesterone varies widely. This is due in part to the fact that there have been no long-term, double-blind, placebo studies—the gold standard doctors trust—on endogenous progesterone. A shortage of studies doesn't mean our current knowledge of progesterone is incorrect, just that science doesn't yet have all the answers.

Most of what we know about progesterone today, therefore, comes from various small studies, research on the effects of progesterone supplementation, the clinical observations of several pioneer physicians (such as Dr. John R. Lee, Dr. Katharina Dalton, Dr. Joel Hargrove, and Dr. John Warner), and the anecdotal wisdom of women who experience the effects of this hormone every month.

Some of the data and references provided below are based on points made by the iconoclastic John R. Lee, MD. We at Project AWARE believe in the importance of skepticism and questions in a medical environment which too seldom challenges the medical-pharmaceutical complex and provides all the following information so that women can make informed decisions.


Progesterone is one of the 2 main hormones (the other being estrogen) produced each month by the ovaries of menstruating women (and is produced in smaller amounts by the adrenals). It is the major female reproductive hormone during the latter 2 weeks of the menstrual cycle, made by the corpus luteum of the ovary. It is normal for the levels of progesterone to rise and fall during the monthly cycle. Progesterone production starts just before ovulation each month and increases rapidly after ovulation. It is what enables the fertilized egg to survive.


During the first 2 weeks of a normal menstrual cycle, estrogen is the dominant hormone. In response to ovulation around day 14 of the cycle, estrogen levels drop and progesterone levels rise and assume dominance for the final two weeks of the month. When progesterone levels drop the next menstrual cycle begins in about 48 hours.

• Helps use fat for energy
• Facilitates thyroid hormone action
• Natural antidepressant
• Natural diuretic
• Normalizes blood sugar levels
• Restores proper cell oxygen levels
• Helps restore libido
• Normalizes zinc & copper levels
  • Normalizes blood clotting
• Protects against breast fibrocysts
• Provides some protection against breast cancer
• Necessary for survival of embryo
• Stimulates osteoblasts (bone building)
• Precursor for cortiscosterone production (cortisone)
• Necessary for production of nerve myelin

Estrogen dominance (a term first proposed by Dr. John R. Lee) is a situation in which there is too much estrogen in relation to progesterone. When a woman fails to ovulate, progesterone cannot reach the optimum 20 - 25 mg. during the final two weeks of a woman's monthly cycle. This allows estrogen to go unopposed the entire month and upsets the normal progesterone/estrogen balance. During his 30 years clinical practice, Dr. Lee discovered that estrogen dominance was responsible for a number of unpleasant side effects in his patients, among them: bloating, water retention, breast tenderness, and depression.


--> Synthetic Estrogens In Our Food.
Animals in industrialized countries, especially the U.S., are routinely fed synthetic estrogens and eat grain and grasses that are laden with pesticides. These synthetic compounds are concentrated in the fat of the meat and dairy products sold commercially.

--> Xenoestrogens In Our Environment
Substances with a hormone-like effect on the body, mostly petrochemically based. These chemical compounds, the majority of which mimic the action of estrogen, can be found in such everyday items as soaps, perfumes, medicine, and plastics.

--> Synthetic progestins sold by prescription. Research has shown that synthetic progestins can block the production of our own progesterone by occupying [blocking] progesterone receptors, preventing the natural progesterone molecule from performing its tasks.


The simple truth is, when a woman fails to ovulate, her ovaries do not produce progesterone for that month. Research has found that women can begin to skip ovulations as early as mid-late 30's, with the missed ovulations becoming more frequent as perimenopause approaches. While a woman's estrogen may eventually drop at menopause 40-60%, a woman's progesterone level can drop proportionately lower as ovulation ceases, upsetting the natural balance (though some is still being produced by the adrenals), as evidenced below in the reference range chart for progesterone levels in females:

Follicular phase: 0.1-1.5 ng/ml (1st half of the monthly cycle)
Luteal phase: 2.5-28.1 ng/ml; (mid cycle)
Mid-luteal phase: 5.7-28.1 ng/ml;
Postmenopausal: undetectable-0.2 ng/ml;
Oral contraceptives: 0.1-0.3 ng/ml;
Pregnant: first trimester 9.0-47.0 ng/ml;
second trimester 6.8-146.0 ng/ml;
third trimester 55.0-255.0 ng/ml.


One way is to take a natural progesterone supplement. Natural progesterone can be obtained:
1. in lower strengths (1.5%-2%) over the counter** at health food stores,
2. in higher concentrations and in various forms available by prescription only, generally taken along with an estrogen supplement. See our listing of Typical HRT products.

** It is important when choosing over-the-counter natural progesterone to know that not all progesterone creams are created equal. According to Dr. John Lee, for appropriate dosing, a natural progesterone cream must contain at least 500mg USP natural progesterone (not yam cream) per one ounce of cream base.


There are mixed feelings on this issue among medical professionals. The primary reason women on HRT are prescribed progesterone is to protect from uterine cancer. Many doctors believe that, if there is no uterus, there is no need to supplement progesterone. However, research continues to indicate that progesterone has multiple roles within our bodies such as, among other things, bone-building, helping protect against breast cancer, and helping in the production of nerve myelin. Progesterone is a crucial HRT component to discuss with your healthcare provider, whether or not you have a uterus.


This is the question most frequently asked of Dr. Lee during his more than 30 years of active clinical practice.

To quote from Dr. Lee:
"The medical-industrial complex refers to the close knit association of organized medicine with the pharmaceutical manufacturers and governmental medical regulatory agencies....The system taken together is neither necessarily corrupt nor evil, but, like any human agency, is subject to the frailties and faults of humankind. Medical research is dependent on the $billions of grants from the National Institutes of Health (NIH) and the private pharmaceutical industry. The two are closely interlocked......

Any given pharmaceutical company, like any private enterprise, must make a profit to stay alive. Profit comes from the sales of patent medicines. The system is not interested in natural (non-patentable) medicines, regardless of their potential health benefits. Thus the flow of research funding does not extend to products which cannot be patented.

Few people know that the definition of malpractice hinges on whether or not the practice is common among one's medical peers and has little (usually nothing) to do with whether the practice is beneficial or not. A doctor willing to study, to learn the ins and outs of an alternative medical therapy, and to put what he has learned into practice in helping patients is potentially exposing himself to serious charges of malpractice.....

But what does all of this have to do with natural progesterone? The answer is quite simple, really. Ample medical research regarding progesterone was carried on in the 1940's through the 1960's, and amply reported in mainline, recognized medical literature. Since the early 1970's, however, medical research has become much more expensive and the grants subsidizing progesterone research, (or any unpatentable medicine or treatment technique), have dried up and been blown away by the contemporary trade winds of synthetic drugs, particularly the progestins. The potential market for patentable progestins is vast -- contraceptive pills, irregular menses, osteoporosis.... -- literally every woman through the age of puberty on is a target for a sale. Do you think the prevailing powers wish to see this lucrative market left to an over-the-counter natural product not in the hands of physician prescribers and not controlled by the pharmaceutical industry?

Thus, when he (the physician) hears of the use of natural progesterone, he wonders why none of his associates know about it. If it is not commonly known, 'it must in some way be false and/or unapproved.' Having given lectures on the role and medical uses of natural progesterone, I have observed numerous instances wherein perfectly fine physicians will inquire about obtaining the product for use by their wives or mother-in-law but not for their patients. What can account for such behavior by professionals? I suspect that it is fear of alienation from the flock that is paramount in their minds....

If progestins were the equivalent of natural progesterone in effect and safety, the argument would be moot. But progestins are not the equivalent of natural progesterone and never will be.......

Patients are aware that they can not leave their health care solely in the hands of the doctor. They must assume responsibility for their own health..........."

Dr. John R. Lee, California, USA



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Campbell, B.C., and P.T. Ellison. 1992. Menstrual variation in salivary testosterone among regularly cycling women. Horm Res 37:132-36.

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Adrenal Fatigue
Cortisol and Weight
DHEA or Testosterone for Women
Estrogen and Memory Loss
HRT for Breast Cancer Survivors and Women at High Risk for Cancer
Human Identical Hormones
Premarin, Facts and Opinions
Progesterone FAQ
Synthetic Progestins and Natural Progesterone, Differences
Natural Progesterone, What Role in Women's Healthcare
Tamoxifen for Prevention of Breast Cancer
Testosterone and Its Benefits to Women
Testosterone's Impact on Postmenopausal Women...
Thyroid Hormone, Symptoms, and...
Typical HRT Products
Where to get Natural Hormones
Herbal Allies, An Introduction
Alternative Remedies for Menopausal Symptoms






































Adrenal Fatigue
Cortisol and Weight
DHEA or Testosterone for Women
Estrogen and Memory Loss
HRT for Breast Cancer Survivors and Women at High Risk for Cancer
Human Identical Hormones
Premarin, Facts and Opinions
Progesterone FAQ
Synthetic Progestins and Natural Progesterone, Differences
Natural Progesterone, What Role in Women's Healthcare
Tamoxifen for Prevention of Breast Cancer
Testosterone and Its Benefits to Women
Testosterone's Impact on Postmenopausal Women...
Thyroid Hormone, Symptoms, and...
Typical HRT Products
Where to get Natural Hormones
Herbal Allies, An Introduction
Alternative Remedies for Menopausal Symptoms







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Updated 09/29/2010