The term "bioidentical hormones" refers to hormone supplements that have the same structure as our own hormones. Usually used in the context of female menopausal hormone therapy, these compounds are derived from soy and Mexican wild yam.

Rationale

Studies have found that the traditional synthetic hormones used in menopausal hormone therapy increase many health risks. The search for safer alternatives led to bioidentical versions.

Lack of Controlled Studies

The American Association of Clinical Endocrinologists has cited the lack of large controlled studies as a reason not to recommend bioidentical hormones. Pharmaceutical companies lack the financial incentive to conduct studies because they cannot patent the ingredients, according to Dr. R.S. Isaac Gardner on his website PsychoNeuroEndocrinology.com.

Possibly Non-Uniform Dosage

The FDA says there is no way to know if a compounding pharmacist is providing the correct dosage or mixing it properly to ensure a uniform amount of hormone in each dose.

Little FDA Oversight

Over-the-counter products might not be inspected by the FDA, so they can contain inferior or ill-measured ingredients.

Considerations

The FDA states it is possible that bioidentical hormones can cause the same problems as synthetic hormones, but no studies have been done to show this. Soy and yam were used for centuries for gynecological symptoms with no recorded ill effects.

Source:

Psychoneuroendocrinology.com: A Discussion about Bioidentical Hormones

FDA.gov: Bio-Identicals, Sorting Myths from Facts