Say “progesterone” and most people—especially women—immediately recognize it as a female hormone because it is so closely associated with pregnancy and menstruation. And they are partly right, as one of progesterone’s most important functions is to cause the endometrium to secrete proteins during the second half of the menstrual cycle to prepare the uterus to accept an implanted fertilized egg. Progesterone is also associated with premenstrual syndrome (PMS), as low levels of this hormone are believed to be responsible for symptoms such as mood swings, water retention, breast tenderness, and headache, among other complaints.

In fact, many of the complaints men and women have about aging—weight gain, insomnia, anxiety, depression, and migraine in women; weight gain, loss of sex drive, and prostate enlargement in men—are associated with an imbalance between estrogen and progesterone that is common in both men and women.

Functions of Progesterone

Maintaining the uterine lining and preventing excess tissue buildup (which can result in endometriosis) Inhibiting overgrowth of breast tissue Increasing metabolism and promoting weight loss Balancing blood sugar (glucose) levels Acting as a natural diuretic Normalizing blood clotting

Stimulating the production of new bone, which is important in preventing osteoporosis Enhancing the action of thyroid hormones Alleviating depression, reducing anxiety, and balancing mood Promoting normal sleep patterns Preventing cyclical migraines Restoring proper cell oxygen levels Improving libido

Decline in Progesterone/Estrogen Dominance

Women’s progesterone levels typically begin to decline when they are in their early to mid thirties, and production declines much more rapidly than does estrogen production. This drop in progesterone levels causes the body to become estrogen dominant; that is, the natural ratio of estrogen to progesterone is out of balance. This typically means one of the following:

• estrogen levels are extremely high;
• estrogen levels are normal and progesterone is low, or
• estrogen is low and progesterone is extremely low.

Estrogen dominance causes various metabolic disturbances, the most common of which is weight gain because the body is unable to effectively burn stored fat for energy. Also, estrogen dominance compromises the body’s ability to metabolize all types of calories or to distribute body weight evenly. Another indication of estrogen dominance is water retention and fat deposits on the hips, thighs, and abdomen.

While estrogen dominance is usually thought of as a “female” problem, excess estrogen in men can be detrimental as well. Along with the increased risk for cardiovascular and inflammatory diseases, elevated estrogen in men is associated with breast enlargement (gynecomastia), weight gain, prostate enlargement, and a decline in sexual function.

Using Natural Progesterone

The form of bioidentical progesterone that we recommend is micronized progesterone USP. Micronized progesterone is available as a gel, which is the form we prefer, and in capsule and tablet form. Micronization of progesterone is a process that creates minute crystals of the hormone, which are more readily and steadily absorbed through the skin or from the gastrointestinal tract. The USP stands for United States Pharmacopoeia, a national standard of purity for ingredients used in cosmetics and drugs. A micronized progesterone product that has USP on the label is your guarantee that the progesterone has been converted to a bioidentical form. Some progesterone gels contain wild yam extract only but have no USP progesterone. We have found these products to not be as effective because the body cannot convert yam extracts into progesterone.

Micronized progesterone gel should have an oil/water base, which increase the ability of the hormone to penetrate beyond the skin barrier and diffuse into your bloodstream. We recommend a micronized gel that delivers 50 mg/mL, which is available through compounding pharmacies. When we prescribe progesterone gel for women, we emphasize that it should be applied in a cycle that mimics a healthy woman’s normal menstrual cycle; that is, it should be applied in the morning. For some women and men, applying 25 percent of the daily dose at night more closely mimics their natural cycle, and this is something we help patients determine based on their feedback from the Program.