Progesterone is produced in the ovaries before menopause, after which some progesterone is produced in the adrenal glands. Traditional hormone replacement therapy involves the use of synthetic progesterone, which is called progestin. Use of this artificial version of progesterone is associated with numerous adverse effects, including increased appetite and weight gain, depression and decreased energy levels, hair loss and acne, insomnia and impaired blood lipid levels.
In contrast, use of bio-identical progesterone, which is identical in its chemical structure to naturally occurring progesterone, has numerous health benefits. The effects of bio-identical progesterone are virtually the opposite to those of progestin and include an increased metabolic rate, natural antidepressant and calming effects, increased energy levels, increased scalp hair growth, improved sleep and improved blood lipid levels.
Bio-identical progesterone has also been shown to improve the beneficial effects of estrogen, including those on the circulatory system. While progestin can cause coronary spasm and increase the risk of heart disease, bio-identical progesterone has not been linked with these side effects. Further, bio-identical progesterone has been associated with a reduction in cancer risk in numerous organs, unlike progestin, which protects only against uterine cancer.
It is thought that these differences arise from the fact that progestin binds to progesterone receptors, but does not have the same physiological effects as naturally occurring progesterone. Further, by binding to progesterone receptors, progestin inhibits the binding of any natural progesterone, thus resulting in a state akin to progesterone deficiency. Bioidentical progesterone replacement therapy is therefore a better, and safer, treatment option.