Estrogen is not one hormone, but rather the name of a group of hormones. There are three principle forms of estrogen found in the human body estrone, estradiol and estriol, also known as E1, E2 and E3 respectively.

There is also a group of compounds called phytoestrogens, which are not hormones but occupy estrogen receptors in the body and offer protection against xeno-estrogens in the body.

Estradiol (E2) is the primary estrogen produced by the ovaries. Estrone (E1) is formed from estradiol. It is a weak estrogen and is the most abundant estrogen found in the body after menopause. Estriol (E3) is produced in large amounts during pregnancy and is a breakdown product of estradiol. Estriol is also a weak estrogen and may have anti-cancer effects and is the primary form of estrogen used to treat hot flashes, night sweats and vaginal dryness.

Before menopause estradiol is the predominant estrogen. After menopause estradiol levels drop more than estrone so that now estrone is the predominant estrogen.

The fact is, you cannot live without estrogen. Estrogen is not merely a "sex" hormone, as there are presently three hundred known functions for estrogen in the body and we are only beginning to understand all its interactions. Every cell in your body has receptors--what you might think of as little landing docks--that receive the complex hormonal messages circulating through your blood. There are estrogen receptors in all your vital organs--such as your brain, your heart, and your liver--and all through your body. Estrogen spurs the production of an important enzyme in the brain that helps the connections between brain cells to flourish. It is estrogen that helps maintain verbal learning and enhances a woman's capacity for new learning.(3) Indeed, estrogen supports you from birth until death.

Most of the time, estrogen has lovely effects: it ripens a woman’s sexuality and strengthens her bones, blood vessels, and memory. But it also has a dark side: playing a role in the development of breast and uterine cancer. As scientists unknot the intricacies of that role, they are using the knowledge to develop better anti-cancer drugs.

The Way Estrogen Works
Once released by the ovaries, estrogen travels through the bloodstream to certain body parts, including the breasts and uterus that contain a kind of welcoming committee called estrogen receptors. These protein molecules live inside specific tissue cells and essentially act as cellular on-off switches.

Scientists believe that estrogen’s stimulation of breast and uterine receptors may kick off a process that can lead to cancer development in those tissues. In fact, one concern about long-term, estrogen-based hormone replacement therapy (HRT) is the potential harm from constant stimulation of these receptor “switches.”

In the absence of estrogen, estrogen receptors just sit quietly within our tissues. But when estrogen is around, it binds to the receptors inside the cells, altering their shape. The new entity of estrogen-plus-receptor binds to sections of DNA – our genes’ steering wheel – in the cell nucleus. And that’s where the trouble seems to begin. In some people, the binding activates genes along the DNA strand, guiding the manufacture of new proteins that can lead to cell damage and ultimately, cancer.

How Cancer Cells Grow
It turns out that a large percentage of breast cancer patients also have estrogen receptors in their cancer cells. These cancer cells tend to grow and multiply when stimulated by estrogen – in other words, they are “switched on.”

When surgeons remove breast cancer, laboratory technologists test the cancer cells to see if they contain these hormonal switches – and around 75% of them do. The presence of a significant number of cells with hormone receptors indicates that estrogen is likely driving the cancer.

Thanks to science, however, treatments that address estrogen-fed breast cancers can block the interaction between estrogen and the receptor, removing a key stimulator for cancer growth.

What's Your Breast Cancer Risk?
The biggest risk factor for developing breast cancer is simply being a woman, though a small percentage of men develop it, too. Fortunately, with better screening processes for early detection, breast cancer doesn't have to be fatal.

Looking Younger Than Ever
What has become evident in the United States is that women act and look younger for their age than in previous generations--forty today is what thirty was twenty years ago. Actresses can now actually be sexy onscreen past forty--Susan Sarandon, Jessica Lange, and Meryl Streep, to name just a few--which was not true a generation ago. Marilyn Monroe was considered over the hill at thirty-six. And now fifty for a woman is what forty was twenty years ago.

What's the secret?
One thing we know is that these contemporary actresses are taking very good care of themselves. In fact, American women in general are taking advantage of a physical youthfulness that has been biologically possible for a long time. And they don't want to sink into the "Age fifty plus spends her life in the doctor's office" syndrome.

We're on the side of looking good at any age. We believe there is such a thing as healthy vanity. Wanting to look and feel beautiful is a woman's right. Some women have defensively embraced the idea of an old age with wrinkles and without sex. That's certainly an option. But any expectation you may have that after fifty you will turn into an old woman sitting on a park bench talking about her ailments is the function of an acculturated image. It doesn't have to be that way.

But the first step in taking full charge of your "second spring" is getting on good terms with your hormones--that is, understanding how they work in your body, and what you need to do to keep them balanced--and most important, learning how the plant-based diets and herbal medicines have supported human life for millions of years and are crucial to the well-being of women.