Natural progesterone, which has many beneficial functions that are described in a new book* by John R. Lee, MD,

On the other hand the various synthetic progestins are not precursors of the adrenal hormones or the sex hormones and cannot be easily broken down by the liver. Dr. Lee mentions many side effects from synthetic progestins, including that they may

In this review of Dr. Lee's book the effects of natural progesterone in combating female infertility, osteoporosis, and cancer will be outlined. .

In the menstrual cycle at the crucial time—right after ovulation— low levels of progesterone in relation to estrogen can result in female infertility. Progesterone is the natural hormone "that makes possible the survival of the fertilized egg." It is produced by a special tissue (corpus luteum) formed by the follicle from which the matured ovum emerges. Progesterone is essential for the proper development of the uterine lining so that it can receive and nourish a fertilized ovum. "As the placenta develops, it assumes and progressively increases the production of progesterone for the duration of the gestation period, i.e., until birth of the baby. During the third trimester, progesterone is produced at the rate of more than 300 milligrams per day, an astounding level of hormone production which, for other hormones, is usually measured in micrograms per day. . . . Progesterone (unlike estrogen and testosterone) is devoid of secondary sex characteristics. Thus, its effects in promoting the development of the fetus are independent of the baby's gender. The fetus is allowed to develop according to its own DNA code and not be affected by the hormones of the mother."

"Bones are living tissue and, unlike teeth, they can grow as the body grows, mend when broken, and continually renew themselves throughout life. Bone can be thought of as mineralized cartilage. . . . Bone forming cells (osteocytes) differentiate into osteoclast and osteoblast varieties. Osteoclast cells continually travel through bone tissue looking for older bone previously mineralized and in need of renewal. Osteoclasts resorb (dissolve away) such bone leaving tiny unfilled spaced (lacunae) behind. Osteoblasts then move into these spaces and produce new bone. This astounding process of continual resorption (by osteoclasts) and new bone formation (by osteoblasts), called remodeling, is the mechanism for the remarkable repair abilities and the continuing strength of our bones.

At any stage in life, one's bone status is a product of the balance between these two functions of bone resorption and new bone formation. . . .

  • Estrogen retards osteoclast-mediated bone resorption
  • Natural progesterone stimulates osteoblast-mediated new bone formation
  • Some progestins [synthetic forms of progesterone, which can be patented, used profitably in birth control pills, and which have many deleterious side effects] may also stimulate new bone formation to a lessor degree."

Many factors are involved in osteoporosis. Exercises, particularly weight-bearing ones, and appropriate nutrition are absolutely essential for avoiding osteoporosis.

Mineralized bone (hydroxyapatite) is a crystalline structure and, as such, will respond to physical stress just as other crystalline structures do. In particular, any force tending to distort the crystalline arrangement generates an electric voltage, called the piezoelectric effect, producing a small electric current (discovered by Pierre Curie in 1883). This also happens in mineralized bone and may explain the wondrous ability of osteoclast and osteoblast action in constructing and reinforcing bone trabeculae along lines best suited for maximum strength and physical efficiency. When viewed microscopically, trabeculae remind one of the vaulted chambers and flying buttresses of the best Gothic churches.

Dr. Lee deals with many factors in the treatment of postmenopausal osteoporosis and summarizes as follows:

Since calcium is the predominant mineral in bone building, it is helpful to follow the chain of events that facilitate its bone use from ingestion to incorporation into bone.

facilitating factors

Ingested calcium
gastric hydrochloric acid (HCl) and vitamin D

Absorbed calcium
exercise, progesterone (stimulates osteoblasts), estrogen (restrains osteoclasts), magnesium, micronutrients. Avoid excess protein, diuretics, antibiotics, fluoride, and metabolic acidosis.

Bone incorporation

Natural progesterone is effectively absorbed through the skin. Dr. Lee. has had excellent success increasing the bone density of osteoporotic patients who used progesterone cream, not constantly but as prescribed, along with a diet emphasizing leafy green and other vegetables ("Over 5000 plants contain progesterone-like substances.") plus supplements, and appropriate exercise.

Interestingly, "a comparison of patients younger than 70 years of age with those over 70 showed no difference in the bone response to progesterone. Further, patients who are now well up in their 80's continue to enjoy strong bones without evident bone loss while continuing their use of natural progesterone. Age is not the cause of osteoporosis; poor nutrition, lack of exercise, and progesterone deficiency are the major factors."

Breast cancer and uterine cancer are promoted by some and controlled by other gonadal hormones, namely, the estrogens and progesterone. The three principal estrogens produced by our bodies are estradiol, estrone, and estriol. The latter is particularly high during pregnancy. In the Journal of the American Medical Association in 1966, "it was reported that women with breast cancer excreted 30 to 60 per cent less estriol than non-cancer controls; and that remission of cancer in patients receiving endocrine therapy occurred only in those whose estriol quotient rose." On the other hand, estradiol and estrone are known promoters of uterine cancer. Specifically, "among the three major natural estrogens, estradiol is the most stimulating to breast tissue, estrone is second, and estriol by far the least."

What about progesterone? Breast cancer and uterine cancer tend to occur when estrogen levels are high relative to progesterone. Dr. Lee calls this "estrogen dominance."

In the case of breast cancer, consider the following observations:

The cancer protective benefit of progesterone is clearly indicated by the prospective study in which premenopausal women with low progesterone levels were found to have 5.4 times the risk of developing premenopausal breast cancer and a 10-fold increase in deaths from all malignant neoplasms compared to those with normal progesterone levels. . . .

Thus, the evidence is strong that unopposed estradiol and estrone are carcinogenic for breasts, and both progesterone and estriol, the two major hormones throughout pregnancy, are protective against breast cancer.

Dr. Lee asks why the natural and beneficial hormones progesterone and estriol are not prescribed for women rather than the deleterious synthetic estrogens and progestins. He answers by pointing out that the synthetic forms, which are never found in any living creature, can be patented and sold profitably and that many doctors, who get advertisements for the synthetic products from the pharmaceutical companies, are not aware that the natural hormones, progesterone and estriol are also available.

[Editor's note: I thoroughly enjoyed reading Dr. Lee's book. It is delightfully written and most informative.]

*Natural Progesterone: The Multiple Roles of a Remarkable Hormone , BLL Publishing, P.O. Box 2068, Sebastopol, CA 95473; 99 pages, paperback, $11.95.

Article from NOHA NEWS, Vol. XIX, No. 4, Fall 1994, pages 6-8.