Menopause, Estrogen, hormones, hormone replacement therapy, HRT, progesterone, menstrual cycles, sex, sexual development, reproductive system

Estrogen

Estrogen is a hormone manufactured naturally by a woman's body. It is essential for normal female sexual development and for the healthy functioning of the reproductive system. It plays a pivotal role in the early maturation of the vagina, uterus, fallopian tubes, and other female organs, as well as secondary sex characteristics such as the enlargement of breasts and hips. In concert with progesterone, another female hormone, estrogen issues the instructions that sustain each menstrual cycle and prepare the uterus for pregnancy.

Estrogen is Not a Single Hormone

Unlike the popular myth, estrogen is not a single hormone. The term "estrogen" is really short-hand for a group of several different but related hormones that perform the functions we normally attribute to "estrogen." Technically, it's more accurate to speak of "estrogens." In adult human women, three different natural estrogens predominate:

• Estrone (approximately 10-20% of circulating estrogens)

• Estradiol (approximately 10-20% of circulating estrogens)

• Estriol (approximately 60-80% of circulating estrogens)

Under normal circumstances, hormone levels vary according to the stage of the menstrual cycle, but the amount of each hormone usually fluctuates within the proportions above.

We can compare this estrogen "blend" with Premarin, a popular conjugated equine estrogen used in HRT. It contains primarily just one "human" estrogen, estrone (75-80%), plus equilin (6-15%), a form of estrogen found exclusively in horses (plus smaller amounts of estradiol, which is also found in humans) and two other horse estrogens.

The majority (over 90 percent) of the estrogen present in a pre- menopausal woman's body is made in the ovaries. A smaller additional quantity of estrogen is produced by the adrenal glands and peripheral tissues such as fat, liver, and kidneys by converting androgens to estrogens. Estrogen hormones are also formed in the placenta during pregnancy.

At menopause the ovaries stop producing estrogen. However, the other sources continue to produce estrogen. But the total quantity available to the body is much smaller as the major contributor to the estrogen production, viz., ovaries, are not producing anymore. The important point to remember is that due to these other sources, the body does not just stop producing estrogen at menopause. Also, because of the estrogen converted by androgens in fat cells, over- weight women may suffer less from menopause-related problems, such as hot flashes and osteoporosis, which are related to estrogen depletion. Yet they can be more at risk for diseases that have been linked to estrogen output, such as endometrial and breast cancer. Researchers have shown that because overweight woman have less of the protein SHBG (sex hormone-binding globulin) which serves as a carrier for estrogen, less estrogen is bound to SHBG. Therefore more estrogen remains more active or potent within their systems.

Women have dozens of types of circulating estrogens. Three of them are important. They are: estradiol, estrone, and estriol.

Estradiol

Estradiol is produced by the ovaries. It is the primary circulating estrogen before menopause. It is also the strongest estrogen and is responsible to the monthly ovulation and normal menstrual cycles.

Estrone

Estrone is produced by the fatty tissues. It is less potent than estradiol, but takes more importance after the menopause, when estradiol is reduced. is produced by the fatty tissues. It is less potent than estradiol, but takes more importance after the menopause, when estradiol is reduced.

Estriol

Estriol is an estrogen that is prominent mostly during pregnancy. It is made from a combination of components from the placenta, fetus, and mother. is an estrogen that is prominent mostly during pregnancy. It is made from a combination of components from the placenta, fetus, and mother.

Estriol Is Not a Weak and Unimportant Estrogen

Estriol has been largely overlooked by most American physicians and pharmaceutical researchers, who have long considered it to be an inactive, or at best, a weak and unimportant metabolite of estrone and estradiol. This, unfortunately is another myth that is completely wrong!

It appears that the primary cancer danger from synthetic HRT does not come from "unopposed" estrogen, but from "unopposed" estradiol, estrone, and equilin. A number of scientific studies have demonstrated that estriol's unique, and perhaps most important role may be to oppose the growth of cancer, including cancer promoted by estradiol and estrone, themselves.

• The results of animal studies have suggested that when natural estradiol and estrone are "opposed" with estriol in normal (physiologic) proportions, the risk of cancer due to hormone replacement virtually vanishes.

• When taken by itself, even in relatively high doses, estriol does not increase endometrial proliferation.

Doctors in Europe have been prescribing estriol as a safe and effective alternative to 100% estradiol or Premarin for years. They have found it especially helpful for women with disabling postmenopausal symptoms, such as vaginal thinning, painful sexual intercourse, recurrent urinary tract infections, and urinary incontinence.

The actual levels of estrone may rise after menopause. But the total estrone in postmenopausal women is insufficient in quantity and activity to override the functional loss of estradiol. The loss of total estrogen activity is evidenced by resulting symptoms and changes, such as hot flashes and bone loss.

There are many sources of estrogen.

Estrogen naturally made by the body.

Family Tree - Where Do Hormones Come From?

Hormones, even natural ones, are made, not born. Our bodies create the natural hormones we need from nutrients, with the help of enzymes. Estrogens, androgens, progesterone, and other members of the steroid family can all trace their roots back to a single "ancestor" molecule. It's a fatty substance known as cholesterol!

Although we spend lot of time and money to devise strategies on how to lower cholesterol in our bodies, cholesterol is actually a vital substance our bodies require for (among other reasons) producing the full range of steroid hormones. No cholesterol, no estrogen, no testosterone. Although the body produces much of the cholesterol it needs in the liver, it is not uncommon for people who go on extremely low-fat, low-cholesterol diets to find that their hormonal balance is disturbed.

The Steroid Family Tree begins with cholesterol, some of which is converted to the hormone pregnenolone. Pregnenolone, in turn, begets both progesterone and DHEA. Some progesterone and some DHEA are both converted into androstenedione, a major precursor of both estrone and testosterone. Testosterone, the best-known of the "male hormones," can be converted to the "female hormone" estradiol.

Estrone and estradiol have an interesting relationship. Some estrone is also changed into estradiol, and some estradiol is changed back to estrone. Most of the estrone and estradiol the body produces is quickly converted to estriol. But some estriol can be produced from DHEA or androstenedione without involving estrone or estradiol at all!

Synthetic estrogens produced by pharmaceutical companies.

Their molecular structure is closely similar to naturally occurring estrogens. (As we have shown earlier, the proportion of the "estrogen components" are different than what is found in human system. Since they are produced outside the body, they are also sometimes referred to as exogenous estrogen. During hormone replacement therapy (HRT), exogenous estrogens, as well as exogenous progestins and androgens, are put back into the body to replace those lost to menopause.

Genesis of Synthetic Estrogens

Premarin is a very popular synthetic estrogen used in HRT. It is derived from the urine of pregnant mares (horses) and contains seventeen different types of estrogen, most of which are not native to human beings. Premarin is produced under intensely inhumane conditions. In order to collect horse urine on a scale that makes production profitable, as many 75,000 to 80,000 pregnant mares must be confined in tiny stalls not much bigger than the horse under conditions that have raised serious alarm among people concerned with the welfare of these animals. For most of their 11-month pregnancy, the mares live on restricted fluid intake (so as not to dilute the urine), are allowed no exercise, and may not even be allowed to lie down. After they give birth, they are allowed to nurse their foals for only one week so that they can be impregnated again as soon as possible. These living Premarin factories often die during their second or third pregnancy from the stress of confinement.

Xenoestrogens

Xenoestrogens are estrogen-like compounds that originate from sources other than humans and animals. They can attach to human estrogen receptors, thus affecting the estrogen-receptive tissues and organs in the body. Some xenoestrogens that originate from plants may directly affect existing estrogen levels.

Estrogen Has Far Reaching Effect

Researchers once thought that the estrogen made by the body affected only the uterus. However, we now know that estrogen accounts for much more than a woman's strictly female traits. After leaving the ovaries, estrogen travels to special receiving points, found in different type of tissues all over the body. Many of these receptors are found in female anatomy, such as the breast, uterus, labia, and vulva. But you can also find them in bone, skin, the brain, muscles, heart, and blood vessels.

Estrogen can affect the body positively and negatively. Good news is that it lessens the risk of cardiovascular disease and bone loss. It also may provide some of the vigor characteristics of young age. However, excess estrogen or estrogen metabolized by the body in a certain way can lead to problems. Large or prolonged doses of estrogen can cause breast cancer or carcinoma in the cervix.

Even mild estrogenlike compounds present in plants can trigger adverse reactions when an animal gets too much of them. Scientists have found that pigs that eat too much moldy corn or sheep that consume too much clover may develop an abnormal growth of the uterine lining resulting in high miscarriage rates, and other abnormalities associated with an excessive exposure to estrogen-mimicking hormones.

Other xenoestrogens may indirectly increase or decrease "good" and "bad" estrogens in our body. It is suggested that estrogenlike chlorinated compounds found in pesticides may increase the risk of cancer in both men and women by binding to human estrogen receptors.

Researchers at the Strang-Cornell Cancer Research Laboratory in New York found that the way estrogen is metabolized in the body influences the incidence rate of hormonally related cancers, such as breast and endometrial cancer. They suggested that all ovarian-made estrogen is metabolized by one of two principle pathways. One pathway results in a "good" estrogen (2-hydroxy- estrone); the other leads to a bad, cancer-causing estrogen (16-alpha hydroxyestrone). Factors that affect the metabolic pathway include diet, thyroid hormones, and the presence of xenoestrogens such as pesticide residues.

Thus estrogens can provide benefits or risks depending on whether it is normal or abnormal. Irrespective of the source of the estrogens, they can lead to either risks and benefits for users. HRT is only one of the sources of estrogen. A woman's inherited makeup, current health, diet, and surrounding environment may all play a part in her body's reaction to estrogen.

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