Estradiol versus Estriol versus Estrone; Which Estrogen Is Best?

When it comes to estrogen replacement during perimenopause, menopause, and beyond, the research consistently points to estradiol as the optimal choice. This is due to its significant potency and effectiveness in managing the symptoms associated with these life stages, and it's capacity to protect our heart, bones, skin, vagina, brains and so much more.

Estradiol is the most powerful form of estrogen naturally produced by your body during your reproductive years. While your ovaries are the primary producers, smaller amounts are also created in other areas, including your adrenal glands, fat tissue, liver, breasts, brain, (and even in the testicles for men) (1).

Estriol is typically present in very low levels in non-pregnant women, but its presence significantly increases during pregnancy when the placenta becomes a major producer. It's also a natural byproduct formed from estradiol and estrone within the body. While a natural hormone, it doesn't possess the same strength as estradiol. The North American Menopause Society (NAMS) notes that, "Although estriol is a weak estrogen, it can have a stimulatory effect on the breasts and endometrium." (2). This is why when prescribed Biest (estriol and estradiol in a cream), it is best to have a higher estradiol ratio, for instance; 20% estriol and 80% estradiol.

Estrone is an estrogen that becomes the predominant form circulating in your body after menopause. Interestingly, it can be derived from estradiol and can also convert back into it. Your body also produces estrone by converting androstenedione, a hormone from your adrenal glands, through a specific enzymatic process. The effectiveness of estrone as an estrogen largely comes into play when it transforms into estradiol. This hormone can be found in your reproductive organs and also in your body's fat reserves (1).

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