The Female Sex Hormones: Extrogen and Progesterone, Chapter Six

How Estrogen Fights Aging

Proponents of estrogen cite both scientific studies and the experiences of numerous women to show that this female hormone can ease or eliminate menopausal woes. Estrogen supplements, which are available as skin patches, topical creams, and long-lasting injections, appear to relieve hot flashes, night sweats, and other discomforts, as well as vaginal dryness and atrophy. Some women find that this hormone helps keep their skin thicker, moister, and more youthful-looking.

Collagen, which is stimulated by estrogen, is the main protein in the dermis. A loss of collagen results in increased wrinkling, bruising, and thinning of the skin. Administering estrogen not only prevents collagen loss but also increases collagen synthesis, which can relieve symptoms of diminished urinary control sometimes experienced by menopausal women. Estrogen moistens the vaginal mucous membranes, which increases lubrication, and also helps maintain flexibility of the connective tissues.

Estrogen and progesterone supplements have also been proven to reduce the bone loss associated with osteoporosis. Women's bones slowly begin to lose minerals and become less dense even before menopause. After menopause, however, the pace accelerates rapidly for five to ten years. Estrogen inhibits bone re-absorption and progesterone stimulates bone formation. Unless a woman is taking these hormones, she has about a one-in-four chance of developing serious osteoporosis.

Osteoporosis increases the risk of bone fractures and all their ensuing complications. One study found that older women who took estrogen were subject to only half the number of bone fractures as those women who avoided the hormone supplement.

A recent analysis by the Postmenopausal Estrogen and Progestin Intervention Trial revealed that estrogen alone and in various combinations with progesterone is equally effective in increasing bone mass in postmenopausal women. Data found that fewer than 3 percent of women on estrogen therapy continued to lose a clinically relevant and measurable fraction of bone density at the spine.

By age seventy, almost 50 percent of women have had at least one osteoporotic fracture, at an estimated cost of $17 billion annually in the United States. A menopause symposium sponsored by the Oregon Health Sciences University School of Medicine concluded that estrogen is the therapy of choice for prevention and treatment of osteoporosis. Although supplemental calcium, diet, and exercise are also beneficial, they don't seem to be as effective as estrogen.

The most important benefit of estrogen replacement therapy is the reported reduction in coronary artery disease - the leading cause of death in post-menopausal women. Some 500,000 women die from coronary artery disease per year - that's twice as many women as those who die each year from cancer. Apparently, the high premenopausal levels of estrogen tend to protect women from heart disease, partly by keeping levels of HDL cholesterol high and LDL cholesterol low.

Without estrogen replacement, a woman's risk of heart attack becomes equal to a man's within fifteen years after menopause. Simply being postmenopausal puts a woman at a higher risk for heart disease, and having just one additional risk factor - smoking, high blood pressure, HDL cholesterol below 35 mg/dl, diabetes, or a family history of heart disease - puts her at an even higher risk. With estrogen, however, the blood vessels dilate slightly, cholesterol balance is maintained, and the risk of heart disease vastly decreases. This can be seen in a report from a ten-year study of some 48,470 nurses from the Nurses Health

Study (National Health and Nutrition Examination Survey, or NHANES) - one of the largest studies to date - which found that estrogen use reduced the risk of major coronary disease and fatal cardiovascular disease by half.

Dr. Lawrence Brass of Yale University School of Medicine predicts that ERT may soon emerge as one of the most effective therapies for stroke prevention, cutting the risk of stroke in postmenopausal women in half. He believes that because estrogen prevents heart disease by 50 to 70 percent, it may also "plausibly" prevent stroke.

In a Leisure World prospective cohort study, estrogen therapy was associated with a 46 percent overall reduction in the risk of death from stroke, with a 70 percent reduction in recent users. This protection was present in women both with and without hypertension and in both smokers and nonsmokers. In addition, a population-based cohort study in Uppsala, Sweden, documented a 30 percent reduced incidence of stroke in postmenopausal users of estrogen, as well as in women given an estrogen-progestin combination.

However, a large cohort from the Nurses' Health Study produced results in striking contrast, failing to show a protective effect of estrogen against stroke. However, critics have pointed to the fact that the women in the study were too young, where there was little protective effect against stroke.

Although estrogen is primarily a female hormone, men also produce it. In fact, estrogen levels in men can be higher than in postmenopausal women.

In addition to reducing the risk of cardiovascular disease and osteoporosis, postmenopausal hormone replacement therapy may allow more women to retain their teeth as they age. By preventing osteoporosis, estrogen may add the benefit of preventing tooth loss and the need for dentures in older women. A new study of 3,921 women found that those on hormone replacement were 19 percent less likely to have some tooth loss and 36 percent less likely to have no teeth than women who had never taken hormones. Researchers also suggest that because tooth loss provides a measure of skeletal bone health, it may be the first clinical sign of osteoporosis.

Estrogen also seems to reduce the risk of colon cancer - and the longer a woman takes estrogen, the lower her risk. New research has found that estrogen users had a 29 percent lower risk of dying from colon cancer than non-users; risk for users of ten years or more was 55 percent lower.

The North American Menopause Society suggests that the addition of a low-dose testosterone to oral estrogen therapy may be more effective than estrogen alone in diminishing symptoms of menopause in older women. Hot flashes and vaginal dryness seem to improve, and most significantly, fatigue, insomnia, irritability, and nervousness are relieved.

In order to get the positive benefits of ERT, doctors believe that it should be taken for at least seven years, although a full 95 percent of the women engaged in hormone replacement therapy continue for only three years or less. According to Dr. John Gallagher, an endocrinologist at Creighton University in Omaha, Nebraska, three years is "not long enough to get any positive effects on their bones."

Menopause

An estimated 40 million American women are in or past menopause, with another 20 million due to reach menopause within the next decade. With the increase in life expectancy, many women will be spending one-third or more of their lives in postmenopausal years. Menopause by definition begins after the last spontaneous menstrual period.

Once a woman has gone from six to twelve months without a period, she is considered to have reached menopause. In the United States, the average age for menopause is fifty, although considerable variation certainly exists.

Many people tend to associate menopause with a host of psychological problems, particularly depression, loss of energy, and crying episodes. It isn't clear what amount of these reactions stems from hormonal changes and what may be due to negative images of older women. In any case, many women experience renewed zest and vigor after menopause. Anthropologist Margaret Mead called this period "postmenopausal zest", while author Gail Sheehy commented that postmenopausal women feel "a greater sense of well-being than any other stage of their lives."

Studies show that women who predict that menopause will be miserable do, in fact, suffer more negative emotional and physical symptoms than women who expect it to be easier.

Hot Flashes

Some 85 percent of all women do experience hot flashes, either during peri-menopause or in menopause itself. The physiology of the hot flash is still not understood, but it appears to start in the hypothalamus, "the body's thermostat," in response to a drop in estrogen. During a flash, a woman experiences a severe feeling of heat, especially in the head and neck, often in the entire upper half of the body. Sometimes the face is blotched and ruddy as a result of the dilation of blood vessels on the surface of the skin. In some cases, flashes are accompanied by disruptions in sleep patterns and night sweats.

In the Massachusetts Women's Health Study, the incidence of hot flashes rose from about 10 percent during the perimenopausal stage to about 50 percent just after cessation of menses, and dropped back to about 20 percent four years after menopause.

Flashes usually last for only a few minutes, but may continue for up to an hour. The body will attempt to cool down by beading with perspiration. Hot weather, hot food or drink, stress, and other sources of heat can trigger flashes without warning. Although most women experience them, few - only one in four - find them uncomfortable enough to seek treatment.

Some studies have shown that as little as 15 to 30 IU of vitamin E daily helps ease hot flashes and vaginal dryness, prevents hysterectomy, and in some cases, eliminates the need for estrogen replacement.

Many women who seek estrogen treatment for their hot flashes do find relief. Yet in all cases, whether treated or not, they will eventually stop as soon as the body adjusts to postmenopausal levels of estrogen.

Lower Sex Drive

Another key symptom of menopause is the atrophy of the reproductive tract. Estrogen, produced by the ovaries, keeps the uterus, vagina, and base of the bladder moist and supple. When estrogen levels start to fall, these organs start to shrink, and the vaginal walls thin. Generally, blood flow to the area decreases, as does lubrication. Women may have difficulty controlling their bladders under stress, and they're more likely to suffer from vaginal itching, dryness, and sometimes pain during or after intercourse. As a result, some women become less interested in sex. Other women may experience a loss in libido even without these symptoms.