What Is Bioidentical or Body-Identical Hormone Therapy?

Bioidentical or body-identical hormones are estradiol and progesterone, which are molecularly identical to human hormones. Most (not all) modern menopause hormone therapy is bioidentical. Keep reading for a list of brands.

The difference between “bioidentical” and “body-identical” is that body-identical is the preferred conventional term, while bioidentical is the term traditionally applied to customised hormone formulas dispensed by a compounding pharmacist when compounding was the only way to obtain such hormones.

Today, bioidentical products are available from any doctor and pharmacy and are widely
regarded as safer than non-bioidentical hormone therapy.

Bioidentical hormone therapy is safer

Bioidentical hormones have fewer side effects than contraceptive drugs or older types of hormone therapy, such as conjugated horse estrogens (Premarin®), which were popular in the 1990s.

Did you know? Premarin is an old-style estrogen drug that contains about 30 different hormones, including androgens, many of which are not body-identical. The two main active ingredients are estrone sulphate and equilin sulphate, the second found only in horses. Together, the whole compound is referred to as conjugated equine estrogens and is extracted from pregnant mares’ urine.

Modern estrogen therapy is usually bioidentical estradiol and transdermal (absorbed through the
skin), which allows it to directly enter the bloodstream and not form dangerous blood-clotting factors in the liver. The safest type of estrogen is, therefore, an estradiol patch (Estradot® or
Climara®), gel (Sandrena® or Estrogel®), or vaginal estrogen.

Bioidentical progesterone does not cause mood side effects like progestins. Nor does progesterone carry the heart disease or breast cancer risk of progestins. In fact, according to Professor Prior, progesterone may even help to reduce the risk of breast cancer. 

Bioidentical progesterone is available as oral micronized progesterone capsules (brands Prometrium® and Utrogestan®). All other brands of “progesterone” are actually progestins (not progesterone), and that includes the tablets Primolut® and Provera® and the patch Estalis®. 

Which hormone therapy products are bioidentical?

List of bioidentical versus non-bioidentical hormone therapy

Estrogen versus progesterone therapy for menopause and perimenopause

Transdermal bioidentical estradiol can relieve the hot flashes and mood disturbance of the menopause transition. It’s safest when combined with bioidentical progesterone.

Under current guidelines, the only officially recognised use of oral micronised progesterone is as the progesterone part of hormone therapy – in other words, estrogen plus progesterone, and, even then, only if you have a uterus. As I discuss in Hormone Repair Manual, progesterone can also be used on its own (without estrogen) for perimenopausal symptoms such as night sweats, heart palpitations, sleep issues, migraines, mood problems, and heavy periods. Even without a uterus, progesterone is beneficial for mood and breasts.

👉🏽 Tip: Perimenopause, or “second puberty”, is the two to ten years before periods actually stop. Symptoms include heavy periods, insomnia, anxiety, and night sweats, and are initially the result of losing progesterone, not estrogen. (Later in perimenopause, symptoms can arise from losing estrogen.)

Although estrogen therapy can be helpful, progesterone-alone has a few advantages:

• It’s better for sleep and migraines.
• It’s safer for breasts.
• It’s easier to stop because it’s not addictive like estrogen.

👉 Tip: There’s no progesterone in any type of hormonal birth control.

Progesterone can also make periods lighter and is a good alternative to progestin drugs such as the pill. Bioidentical progesterone capsules can even be used together with the hormone IUD.

For more information about the benefits of progesterone, read:

• Evidence on the use of progesterone in menopausal hormone therapy
• Estradiol and progesterone as resilience markers?

And the following articles by endocrinology professor Jerilynn Prior:

• Women’s reproductive system as balanced estradiol and progesterone actions—a revolutionary, paradigm-shifting concept in women’s health
• Hot flashes? Night sweats? Progesterone can help reduce symptoms of menopause