Claims Refuted

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Menopause
Natural Progesterone
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Alleged Claims Refuted
Progesterone, natural or otherwise, is FDA approved for the following conditions:
  1. amenorrhea
  2. contraception
  3. dysfunctional uterine bleeding
  4. estrogen replacement therapy
  5. infertility

Positive clinical results in the following conditions have also occurred:

  1. premenstrual syndrome (PMS)

  2. corpus luteum insufficiency
To exert the numerous purported effects, natural progesterone must first be absorbed.  In a randomized, double-blind, placebo controlled, crossover study Cooper and colleagues assessed the absorption, metabolism, and urinary excretion of progesterone in post-menopausal subjects. After application of natural progesterone only a small rise, not sufficient to protect the endometrium in HRT or conserve bone, in serum concentrations are seen (Cooper et al.)
In an effort to substantiate Dr. Lee’s work with progesterone and osteoporosis Leonetti and colleagues conducted a year long randomized, double-masked, placebo controlled trial of 90 post-menopausal women.  At one year they found no protective effect of transdermal natural progesterone on bone density. (Leonetti et al.)
  
The American College of Obstetricians and Gynecologists - issued guidelines on the use of alternative treatments such for pre-menstrual syndrome and concluded natural progesterone, primrose oil, and vitamin B6 have either been shown to be ineffective or to be only of limited benefit in treating specific symptoms.

 

As previously noted, absorption of progesterone from a cream formulation may be very low, according to preliminary data.  Additional studies of post-menopausal women who applied topical progesterone for two weeks failed to significantly increase serum progesterone levels.  Levels of 2ng/mL were attained and no dose-response relationship was observed.  

Another study, which utilized a gel based formulation, did find improved absorption and measured peak levels at roughly 8ng/mL. Even these improved peak levels are insufficient to protect the endometrium from estrogenic stimulation during HRT (DTB).  
A randomized, double-blinded, and placebo controlled study failed to show the protective effects of natural progesterone on the endometrium. Endometrial biopsies demonstrated that subjects in the natural progesterone arm of the study showed more proliferative changes than the dydrogesterone treated group. Further, a secretory transformation (a protective effect) was seen more commonly in the dydrogesterone group (DTB).

 

Does Natural Progesterone Work?

What others have to say:
Steven Goldstein, MD
Author of Could It Be Perimenopause.

"To merely say that all perimenopausal symptoms are secondary to estrogen dominance is a gross over simplification.....I have seen patients inadvertently treated this way whose symptoms became worse. I believe it is the fluctuations in unopposed estrogen and thus estrogen withdrawal that often results in many of the symptoms both bleeding and psychosocial."

"The use of birth control pills therefore is totally different. A main thrust of the pill is the fact that it suppresses ovarian function and substitutes a small amount of estrogen and progesterone all month long therefore giving the patient back a steady state equilibrium."

Ruth Jacobowitz, author of 150 Most-Asked Questions About Hormone Replacement Therapy.

"From all the research I have done for my books and lectures and all that I continue to do, I have to say I doubt it. The loss of estrogen at menopause seems to be the culprit and the cause of the so-call nuisance symptoms of menopause---those hot flashes, night sweats, vaginal atrophy, etc.--as well as the long-term serious health problems--such as osteoporosis." 

"Besides so much research, replicated around the world, is demonstrating that estrogen may protect women against heart disease, colon/rectal cancer, Alzheimer's disease, osteoarthritis, dental disease, as well as macular degeneration -- that leads to blindness."