Bioidentical hormones

Bioidentical hormones are made in the laboratory and are based on compounds found in plants (usually soy beans or wild yams). Unlike supplements containing soy or wild yam extract, a bioidentical hormone product has been processed by a specially trained compounding pharmacist.

After the plant-based hormone is processed, its structure is said to be identical to the estrogen, progesterone, or androgen hormone your body produces. (Well-designed studies have yet to prove this theory.1) A compounding pharmacist can offer you a custom-made formulation in one of many forms, such as a capsule, skin cream or gel, tablet to dissolve under your tongue, suppository, or nose spray. Some commonly prescribed estrogens and progesterones are bioidenticals, such as Estrace (estradiol).

Estrogen-progestin hormone replacement therapy (HRT) can cause symptoms that lead many women to stop taking them, such as bloating, breast tenderness, weight gain, and uterine bleeding. These symptoms are thought to be caused by the synthetic progestin.2

Doctors who prescribe bioidentical hormones report that many women have less or no trouble with the symptoms that they get when using synthetic estrogen-progestin HRT.3 This improvement has been linked to bioidentical progesterone.

Just like synthetic HRT, bioidentical hormone replacement is prescribed to increase or stabilize a woman's hormone levels. This is generally done during perimenopause, when hormone levels change unpredictably, and after menopause, when the hormones drop to low levels.

The most important fact to remember about taking bioidentical HRT is that its risks are not yet well understood. It may have the same breast cancer, stroke, blood clot, heart disease, and dementia risks that synthetic HRT has.4


  1. Watt PJ, et al. (2003). A holistic programmatic approach to natural hormone replacement. Family and Community Health, 26(1): 53–63.
  2. Francisco L (2003). Is bio-identical hormone therapy fact or fairy tale? Nurse Practitioner, 28(7): 39–44.
  3. Walker CR (2001). BHRT: A natural option for perimenopause and beyond. Advance for Nurse Practitioners, 9(5): 39–45.
  4. North American Menopause Society (2004). Treatment of menopause-associated vasomotor symptoms: Position statement of the North American Menopause Society. Menopause, 11(1): 11–33.

Last Updated: May 16, 2008

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