Progesterone is used to treat PMS, migraine, irregular menstrual bleeding, mood swings and insomnia, fibroids, fibrocystic breasts and hair loss among other things. Bioidentical progesterone has the same chemical structure and effects of the progesterone made in our bodies, whereas synthetic progestin has a different chemical structure and may have some similar effects as well as different effects. A good comparison is a natural fat versus a trans fat. Both are fats but one is altered to prevent food from spoiling. It took many years to determine that the chemically altered form has some deleterious effects that outweighed the benefits of a more stable food product.
Likewise, natural progesterone and synthetic progestin have some similar as well as different effects. . While bioidentical progesterone and synthetic progestin have indistinguishable effects on uterine endometrial tissue, there is significant evidence that they have different effects on breast tissue. Many studies have shown an increased risk of breast cancer with the use of synthetic progestin and although there were no large scale double blind control studies of the use of bioidentical progesterone, some large scale observational trials in humans and double blind placebo controlled trials in primates show significant differences in the effects of progesterone and progestin on breast cancer and breast tissue. Cells grow (proliferate) and then die off (apoptosis), when they continue unbridled growth, there is potential for overgrowth of tissue – fibrocystic breasts, endometrial (uterine) thickening among other things or if left unchecked, cancer. Studies show that in breast tissue, bioidentical progesterone stops unbridled growth while synthetic progestin does not. Observational trials showed an increased incidence of breast cancerwith the use of synthetic progestin and a reduction in breast cancer risk with the use of bioidentical progesterone.
The bioidentical hormone debate will continue until we have better long term studies that are unbiased by commercial interests, and the gold standard of a double blind, large scale controlled trials which are used to make treatment guidelines. However we can look at the existing studies and weight the risks and benefits of replacement in women who are suffering from severe symptoms associated with progesterone deficiency. Seek the guidance and support of health care professionals who are knowledgeable in the use of bioidentical hormone treatment and uncover other risk factors that may influence your decisions.