Meet Your Estrogens Hormone Harmony

Meet Your Estrogens Hormone Harmony

While many of us have traditionally thought of estrogen as a single hormone, it is
actually a family of hormones comprising several distinct molecules that the body
secretes naturally, the most well known of which are estrone (E1), estradiol (E2),
and estriol (E3). Along with progesterone, testosterone, 5-dehydroepiandrosterone
(or 5-DHEA, commonly known as DHEA), and corticosteroids, estrogens are in the
steroid group of hormones that are all made from the same basic building block:
cholesterol.

Of the three plentiful forms of estrogen just mentioned, estradiol is the most
potent. Primarily a growth hormone, estradiol shapes tissue growth in the vagina,
breasts, endometrium, fallopian tubes, ovaries, bones, and, of course, the
developing fetus. Before menopause, most of your estradiol is produced by the
ovaries, with lesser amounts produced by the adrenal glands, the liver, and the
breasts. Fat cells also secrete estradiol; hence heavier women tend to carry it in
greater concentrations.

Estrone, a weaker estrogen derived from estradiol in the liver, serves as a
backup form of estrogen. Although we stop manufacturing most estradiol after
menopause, the adrenal glands continue to produce estrone after menopause and for
the rest of our lives.

The third key estrogen compound, estriol, plays its pivotal role during
pregnancy, when levels of this “weak” estrogen start to soar. Although scientists
have considered estriol to be too weak to be relevant except during pregnancy, it
now appears that this “weakness” might actually be its strength.

One study (Siiteri et al. 2002) that suggested this was conducted in Berkeley,
California, where researchers examined frozen blood samples of fifteen thousand
women who had been pregnant forty years earlier. They found that of all the study
subjects, those with the highest levels of estriol relative to other estrogens during
pregnancy had the lowest occurrence of breast cancer. Specifically, women with the
highest level of estriol during pregnancy had a 58 percent lower risk of developing
breast cancer than the women with the lowest estriol levels. It’s noteworthy that
during pregnancy, estriol levels climb enormously, by one thousand times or more.

Even after childbirth, estriol levels usually remain higher than they were before
pregnancy.

To summarize, it’s clear from the data that all estrogens are not the same. And it
gets even more interesting than that.