The Medical Letter recently evaluated “bioidentical” hormones and concluded

There is no acceptable evidence that “bioidentical” hormones are safe or effective. Patients should be discouraged from taking them.

“Bioidenticals” include progesterone, estrogens (estriol, estradiol, and estrone), and testosterone. They have mainly been promoted as a safer, more natural alternative to menopausal hormone replacement therapy (HRT), but they are also claimed to increase energy, well-being, and quality of life, and to have an anti-aging effect. Suzanne Somers recommends them for all age groups and both sexes. There is no evidence to support any of those claims.

The whole “bioidentical” thing is a pseudoscientific concept: it is a marketing term rather than a scientifically meaningful one. Bioidenticals are promoted by celebrities like Suzanne Somers, a few maverick medical doctors like Kent Holtorf, proponents of “natural” medicine, patients who were frightened by the Women’s Health Initiative study of hormone replacement therapy, and critics of Big Pharma. The mainstream scientific community is in consensus: a number of medical organizations, from the American Cancer Society to the Mayo Clinic, have issued statements similar to that of The Medical Letter.

The terminology is confusing. Bioidenticals are plant extracts modified to have the same molecular structure as endogenous hormones. But there are FDA-approved Big Pharma hormones that are just as “bioidentical”: they are also plant extracts modified to have the same molecular structure as hormones produced by the ovary. Only one bioidentical hormone, estriol, has no corresponding FDA-approved version. It is only present in large amounts during pregnancy: its safety and efficacy as a supplement have not been tested. Proponents of “bioidenticals” make much of the difference between “artificial” Big Pharma progestins and “natural” progesterone, but that same progesterone molecule is also sold as a prescription drug. (Progestins were originally developed because progesterone is poorly absorbed, but now Big Pharma has developed a micronized version of progesterone that is absorbed adequately.)

One of the biggest concerns is that “bioidenticals” are prepared in compounding pharmacies that are not regulated. The FDA has long been concerned about these pharmacies. In a 2006 survey, the potency ranged from 67.5% to 268.4% of the amount specified on the label, and there were variations within the same samples. Contaminants have also been found, including bacteria. Package inserts describing risks are required for FDA approved products but not for compounding pharmacy products.

From 1990 to 2005, FDA learned of at least 240 serious illnesses and deaths associated with improperly compounded products. Because pharmacists are not required to report adverse events to FDA, there may be additional deaths and injuries of which the agency is unaware.

Another big concern is that dosage is usually guided by salivary hormone levels, which are unreliable. Suzanne Somers even advocates that the patient adjust her own dosage from day to day just depending on how she feels.

Advocates claim that bioidenticals are safer than pharmaceuticals, but since they are essentially the same compounds, there is every reason to think they would have the same side effects. At least 3 cases of endometrial cancer have been reported in women taking bioidentical hormone replacement therapy.

Critics complain that Big Pharma is profit-motivated. Interestingly, bioidenticals are more expensive than the Big Pharma versions of the same hormones and they are not covered by insurance.

Proponents speak of individualizing dosage to “balance” the hormones, but I can’t understand how they could ever hope to do that. The body produces several different hormones and the amount of each varies according to the stage of the menstrual cycle. With each constantly going up or down, how could you define balance or hope to mimic the natural state?

“Bioidentical” hormones may satisfy some of the psychological needs of people like Suzanne Somers, but they don’t satisfy the requirements of science-based medicine or even of common sense.