Reports and Research on Natural Progesterone

Bioidentical hormones have been in use worldwide for over 50 years, and here is some of the documented research on their effectiveness.


It is often mistakenly said that there is no scientific or research reference material on the use of natural progesterone.  This is simply not true, as there exists plenty of information and data in peer-reviewed medical journals but these are simply often not quoted or known about widely enough.

Although Doctors are aware of the facts on natural optimal hormone replacement, it can be helpful to see brought together some of the many reports published in peer reviewed journals which are widely accepted by authorities to be legitimate and well researched.

Here you will find listed some of the relevant data from those peer-reviewed medical journals.

Breast Cancer Res Treat 2007;101:125-134 – “Estradiol and progesterone demonstrated no increased risk of breast cancer. Synthetic estrogen (Premarin® ) and synthetic progestins (medroxyprogesterone and noresterone) all dramatically increased the risk of breast cancer. This was a ten year study of over 100,000 women, the largest and longest study to date comparing natural hormones to synthetic hormones”.

Fertility Sterility 2005 Dec;84(6):1589-601 – “The WHI trial had major design flaws that led to adverse conclusions about the positive effects of hormone therapy. The study included mostly older women that already had cardiovascular disease. The study utilized only medroxyprogesterone (Provera® which we know negates any beneficial effect of estrogen, rather than the bio identical hormone, progesterone”. Multiple other studies with estrogen started early in menopause demonstrate beneficial effects.”

American Family Physicians 2000;62: 1339-46. – “Due to the side effects of synthetic progestin’s, natural progesterone is preferred. Progesterone has proven bio-availability and no side effects making it the preferred hormone for menopause.

Obstetrics Gynecology 1989;73:606 – “Natural estrogen and natural progesterone offer substantial clinical benefit over the synthetic hormones and should be the agents of choice for menopause.”

Maturitas 2003 Dec;46(1):555-58 – “Progesterone reduces proliferation of breast cancer cells and induces cellular apoptosis (kills breast cancer cells)

Japan Journal of Cancer Research 1985 June;76:699-04. American Family Physicians: 2000;62(8):1839. – “Mammary tumor stimulation was reduced both by progesterone and Tamoxifen, more so by progesterone by Tamoxifen which is the drug of choice to treat cancer.”

Mayo Clinic, Women’s Health Source: August, 1999, pg 3. – “The multitude of side effects associated with the synthetic analogues called progestins has stimulated an interest in natural progesterone. Natural progesterone is obtained primarily from plant sources. Natural progesterone has improved bioavailability and fewer side effects when compared with synthetic progestins. Natural progesterone has not been shown to affect mood or cholesterol levels. The synthetic progestins differ from the natural progesterone since they cause fluid retention, abnormal increase in cholesterol, headaches, mood disturbance, depression, and are frequently a cause of discontinuation of hormone therapy”.

Journal of Women’s Health Gender-based Medicine: 2000;9(4):381-7. – “The side effects of the synthetics include bloating, nausea, and depression were eliminated by using natural progesterone. In fact, unexpected improvement in the feeling of well-being was observed when natural progesterone was used.”

Endocrine Reviews: 28(4): 387 – 439 – “Progesterone has metabolic and hepatocellular effects (decreased insulin sensitivity, increased levels and activity of IGF-1, decreased levels of SHBG), which contrast the opposite effects induced by oral estrogen. Within the nervous system, the neuroprotective and promyelinating effects of progesterone are promising, not only for preventing but also for reversing age-dependent changes and dysfunctions. There is strong evidence that the ageing nervous system remains sensitive to the beneficial effects of progesterone, this may also extend to peripheral tissues including the breast, blood vessels and bones.”

Helpful information: 

If you are not certain which hormone you may be deficient in, or have too much of, the following article can be helpful: