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This article was generously contributed by Dr. Gretchen Reis as part of ForeverBetty's commitment to providing trusted, evidence-informed education from experienced menopause and hormone health professionals. The views expressed are those of the author and are intended for educational purposes only. They should not replace personalized medical advice from your healthcare p

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What are Bioidentical Hormones?

What are bioidentical hormones? This is a very good question that is actually asked by patients and doctors. Many people do not know exactly what constitutes “bioidentical” and why that is important. Bioidentical hormone replacement therapy (BHRT) has become quite popular simply because it is a safer way to replace your hormones.

First of all, “bioidentical” simply means that the hormone in that pill or cream is exactly the same molecular structure as the hormone naturally present in our bodies. Hormones that are not bioidentical typically have a few atoms attached or a different configuration of the molecule, so it behaves differently in the human body.

There may be similar effects, such as horse estrogens helping reduce hot flashes like bioidentical estrogen. However, there can be stark differences. Bioidentical progesterone has evidence that it reduces breast cancer cell proliferation, but some non-bioidentical progestins may increase breast cancer cell growth.

To make it more confusing, some bioidentical hormones are available (with a prescription) at typical commercial pharmacies, but some have to be custom compounded. So you don’t always have to go to a compounding pharmacy to get bioidentical hormones.

Essentially, you first have to know whether the hormone you are talking about is bioidentical or not.

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Estrogen

In regards to estrogen, there actually are several types of bioidentical hormones available commercially.

Estradiol is bioidentical, so estradiol patches, vaginal cream and pills are 100% bioidentical. In fact, BHRT physicians use estradiol patches and vaginal cream often. They also often use compounded estrogen topical cream (typically called “Biest”, or estradiol and estriol).

The one type of bioidentical estrogen that should be avoided if possible is oral estradiol pills. Estrogen orally increases triglycerides, increases blood clotting risk and causes a sluggish gallbladder. Other forms of estrogen do not do this, only pills. So pill form estrogen is not preferred.

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Progesterone

“Progesterone” refers to the real, bioidentical hormone.

Compounded progesterone is always bioidentical. Commercially, “Prometrium” is a bioidentical progesterone capsule. It is safe and effective, but only comes in 2 doses and contains peanut oil, which isn’t recommended for patients with someone in their family allergic to peanuts, and it is an immediate release formulation.

Compounded progesterone can be made in any dose and is also usually made as a slow release pill, which many BHRT physicians prefer.

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Progestins

“Progestin” is a term often misunderstood.

It is a category of hormones that includes bioidentical progesterone and non-bioidentical progesterone-like hormones. Most BHRT physicians refer to either “progesterone” or “progestin” to differentiate the two.

Progestins that are non-bioidentical are significantly different molecules that often do not cause the same effects in the body.

For example, progestins tend to cause:

• Anxiety
• Blood clots
• Muscle cramps

Whereas progesterone:

• Has a calming effect
• Does not clot the blood
• Relaxes muscles

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Testosterone

Testosterone, often prescribed to men as an injection, is also often misunderstood.

It most commonly is “testosterone cypionate”, because the testosterone molecule has to be connected to another molecule to be stable. Options include cypionate, propionate and enanthate.

Technically, in the vial, this is not bioidentical. But as soon as it is injected, the body’s enzymes cut off the cypionate part, leaving bioidentical testosterone. So it is considered bioidentical.

For women, testosterone is often used as a compounded cream, which is bioidentical.

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Thyroid Hormones

Thyroid hormones are even more confusing.

Commercial thyroid medications typically are either levothyroxine (“Synthroid”) or porcine thyroid (“Armour”, “Nature-throid”).

Levothyroxine is 100% bioidentical.

Porcine thyroid is not.

Think about it: the manufacturer grinds up pig thyroid gland and puts it in a capsule. It contains T4, T3, other proteins and minerals and other components of a pig thyroid. So it is clearly not bioidentical to humans.

But surprisingly, for some people, porcine thyroid actually works a lot better than the bioidentical levothyroxine.

That is because it has both T4 and T3, and T3 is the more powerful form of thyroid hormone for cellular energy production.

Levothyroxine (bioidentical) has only T4, so your body has to turn it into T3, and some people don’t do that very well.

So the bottom line with thyroid is that it is NOT about bioidentical vs non-bioidentical. It doesn’t matter like it does with sex hormones.

Talk to your provider about what thyroid hormone is best for you.

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Why Does It Matter?

Why does it matter whether you take bioidentical estrogen or progesterone?

Because non-bioidentical hormones have shown health risks in research studies.

The Women's Health Initiative (2002) was a famous study. It showed an increased risk of breast cancer, heart disease, and stroke.

But it is very important to realize that this study used non-bioidentical estrogen (in fact, it used “Premarin”, which is about a dozen types of estrogen from horses) and a progestin.

There have been many experts analyzing these results since then, and has become increasingly clear that the increased risks came from the progestin, and not the estrogen.

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The Bottom Line

The most important concept with hormone therapy is that we want to increase the levels of our OWN NATURAL hormones to optimal levels.

Taking a hormone that is not exactly the same as what your body is making will not work.

When the Kansas City Chiefs have a bunch of players on the sidelines with injuries, do you think they bring in some players from the Cleveland Browns?

Not at all. (Sorry, Browns fans!)

They put in more of their own players, who are part of the team, know the playbook and work well together.

Natural hormones cause natural positive effects.

That's what bioidentical hormone replacement therapy is all about.

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