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Hormones are powerful chemicals that help keep our bodies working normally. They are made naturally, by the body, and can affect us in far-reaching ways. Levels of some hormones decrease as a normal part of aging. In other cases, the body may fail to make enough of a hormone for other reasons. In either case, the body's hormone levels can be increased by taking hormone supplements—pills, shots, or medicated skin patches.

Certain hormone supplements have received a lot of attention lately, including DHEA (dehydro-epiandrosterone), human growth hormone (hGH), melatonin, and testosterone. Unproven claims that taking these supplements can make people feel young again or that they can prevent aging have been appearing in the news. However, when it comes to hormones, more is not necessarily better.

The fact is that no one has yet shown that supplements of these hormones add years to people's lives. And while some supplements provide health benefits for people with genuine deficiencies of certain hormones, they also can cause harmful side effects. The right balance of hormones helps us stay healthy, but the wrong amount might be dangerous.

Another concern is that some hormone supplements are not regulated as drugs by the Food and Drug Administration; they are sold as nutritional supplements, instead. For this reason, the rules controlling how they are produced and sold are not as strict as the rules for drugs. For example, producers of DHEA and melatonin are not required to include important health information on the labels of their bottles. Researchers also have found that the dose listed on the label of some bottles of melatonin may be different from the dose inside the bottle.

Talk to Your Doctor
The NIA does not recommend taking supplements of DHEA, growth hormone, or melatonin, because not enough is known about them. People who have a genuine deficiency of testosterone or human growth hormone (see below) should take them only under a doctor's supervision. The NIA does not recommend taking any supplement as an anti-aging remedy, because no supplement has been proven to serve this purpose. Talk to your doctor to make sure that over-the-counter supplements will not interfere with other medications you are taking and that they will not affect any medical conditions you may have. You might want to show this fact sheet to your doctor, to help explain your concerns.

How Hormones Work
Groups of special cells—glands—make chemicals called hormones and release them into the bloodstream. Hormones taken as supplements also end up in the bloodstream. In either case, the blood then carries hormones to different parts of the body. There, hormones influence the way organs and tissues work.

Hormone supplements may not have exactly the same effects on us that our own naturally produced hormones have, because the body may process them differently. Another difference is that high doses of supplements, whether pills, skin patches, or shots, may result in higher amounts of hormones in the blood than are healthy. When that happens, any negative effects that even the body's own hormones can cause may increase. Tiny amounts of these powerful chemicals, whether made by the body or taken as supplements, can have widespread effects.

DHEA
DHEA is made by the adrenal glands, which sit on top of each kidney. Although it is not known whether DHEA itself causes hormonal effects, the body breaks DHEA down into two hormones that are known to affect us in many ways: estrogen and testosterone (see below). Supplements of DHEA can be bought without a prescription, and also may be found under the name "dehydroepiandrosterone." After people reach the age of about 30, their bodies start to make less DHEA, and the amount of DHEA found in the bloodstream continues to drop as people grow older. Supplements are sold as an anti-aging remedy claimed, by some, to improve energy, strength, and immunity. DHEA is also said to increase muscle and decrease fat.
Right now, there is no reliable evidence that DHEA supplements do any of these things. However, there are early signs that DHEA supplements may lead to liver damage, even when taken briefly.
Some people's bodies make large amounts of estrogen and testosterone from DHEA, while others make smaller amounts. There is no way to predict who will make more and who will make less. Researchers are concerned that DHEA supplements may cause high levels of estrogen or testosterone in some people. The body's own testosterone plays a role in prostate cancer, and high levels of naturally produced estrogen are suspected of increasing breast cancer risk. It is not yet known for certain if supplements of estrogen and testosterone, or supplements of DHEA, also increase the risk of developing these types of cancer. In women, high testosterone levels increase the risk of heart disease and cause growth of facial hair.
Overall, the studies that have been done so far do not provide a clear picture of the risks and benefits of DHEA. For example, some studies show that DHEA helps build muscle, but other studies do not. Researchers are working to find more definite answers about DHEA's effects on aging, muscles, and the immune system. In the meantime, people who are thinking about taking supplements of this hormone should understand that its effects are not fully known. Some of these unknown effects might turn out to be harmful.

Growth Hormone
Human growth hormone (hGH) supplements also are claimed, by some, to reduce the signs of aging - that is, to increase muscle and decrease fat, and to give people a feeling of well-being and energy.

Even though there is no proof that hGH can prevent aging, some people spend a great deal of money on supplements. Shots of the hormone can cost more than $15,000 a year. They are available only by prescription and should be given by a doctor.

Human growth hormone is made by the pituitary gland, just under the brain, and is important for normal development and maintenance of our tissues and organs. It is especially important for normal growth in children. Human growth hormone levels often decrease as people age.

Studies have shown that supplements are helpful to certain people. Sometimes, children are unusually short because their bodies do not make hGH. When they take supplements, their growth improves. Young adults who have no pituitary gland (because of surgery for a pituitary tumor, for example) cannot make the hormone, and they become obese. When they are given supplements, they lose weight.

Researchers are doing studies to find out if hGH can help make older people stronger by building up their muscles and whether it can reduce body fat. They are watching their patients very carefully, because side effects can be serious in older adults. Side effects of hGH treatment can include diabetes and pooling of fluid in the skin and other tissues, which may lead to high blood pressure and heart failure. Joint pain and carpal tunnel syndrome also may occur.

People in search of the "fountain of youth" may have a hard time finding a doctor who will give them shots of hGH. Some people put themselves in danger by trying to get it any way they can. For example, some people went to a clinic in Mexico to get supplements. The clinic was shut down later because side effects were not being carefully monitored by doctors.

Melatonin
The hormone melatonin is made by the pineal gland, in the brain, and decreases with age in some people.

Supplements of melatonin can be bought without a prescription. Some people claim that melatonin is an anti-aging remedy, a sleep remedy, and an antioxidant (antioxidants protect against "free radicals," naturally occurring molecules that cause damage to the body). Early test-tube studies suggest that melatonin may be effective against free radicals, in large doses. However, cells produce antioxidants naturally, and in test-tube experiments, cells reduce the amount they make when they are exposed to additional antioxidants.

Claims that melatonin can slow or reverse aging are very far from proven. Studies of melatonin have been much too limited to support these claims, and have focused on animals, not people.

Research on sleep shows that melatonin does play a role in the sleeping and waking cycle people go through daily, and that supplements can improve sleep in some cases. If melatonin is taken at the wrong time, though, it can disrupt the sleep/wake cycle. The effects of supplements differ from person to person, and more research is needed to find out under what conditions melatonin helps, not disturbs, sleep.

Side effects of melatonin may include confusion, drowsiness, and headache the next morning. Animal studies suggest that melatonin may cause blood vessels to constrict, a condition that could be dangerous for people with high blood pressure or other cardiovascular problems.

The dose of melatonin usually sold in stores—3 milligrams—can result in amounts in the blood up to 40 times higher than normal. It is important to remember that melatonin may be found to have far-reaching effects that are still unknown even at the body's own normal levels, to say nothing of the levels that can be caused by megadoses taken for long periods of time.
Researchers are working to find out more about melatonin's effects.

Testosterone
Testosterone is thought of as a male hormone, but it is found in both men and women. Because men have more testosterone, their voices are deeper, they have more facial hair, and their muscles are larger. Testosterone also plays a role in sex drive and erection.

Testosterone levels may drop as men age, and changes that take place in older men often are wrongly blamed on lower testosterone. For example, the loss of erection some older men experience often is due to unhealthy arteries, not low testosterone levels.
Supplements of testosterone are available, only by prescription, for men whose bodies do not make enough of the hormone. Examples of men who do not make enough testosterone are those whose pituitary glands have been destroyed by infections or tumors, or whose testes have been damaged (the testes are the glands that make testosterone in men, and the pituitary gland helps regulate it).

Supplements provide many benefits for men with a genuine deficiency of testosterone. Men's muscles and bones become smaller and weaker without the hormone, and their sex drive and ability to have erections decrease. Supplements help prevent such problems by restoring normal levels.
But too much testosterone is harmful. Stories about athletes who damaged their health by taking steroids—testosterone supplements—to build up muscle and strength have made headlines. Now, stories about how testosterone can make older men feel young again, and can restore their muscles and their sex drive, have become popular.

The problem is that most of these men already have enough testosterone, and supplements cause them to have more than is normal. The result can be an enlarged prostate gland; harmful cholesterol levels, which may lead to heart disease; psychological problems; infertility; and acne. It is not yet known for certain if testosterone supplements increase the risk of prostate cancer.

Estrogen
Because many women take estrogen supplements for symptoms of menopause, estrogen is included in this fact sheet. Many large, reliable studies have been done on this hormone, and show why it is important to discover both the helpful and harmful effects of a supplement. It is clear that estrogen replacement is helpful to some women after menopause. Women with certain risk factors, however, might decide, along with their doctors, that estrogen supplements are not right for them.

Women have much less estrogen after menopause because the ovaries make dramatically reduced amounts of this reproductive hormone in later life. Studies suggest that reduced estrogen levels are associated with a higher risk of heart disease and osteoporosis—a condition that weakens bones, allowing them to break more easily. These are just two examples of the many areas of the body that can suffer without adequate estrogen.

Research has shown that estrogen supplements prescribed by a doctor can help some women avoid osteoporosis and lower their risk factors for heart disease, the number-one killer of women in the United States. Osteoporosis can lead to severe bone fracture. Patients who are hospitalized for a broken hip have a death rate 12% to 20% higher than others in their age group, due to complications. Estrogen helps prevent osteoporosis.

A recent study suggests that estrogen supplements also may delay the onset of Alzheimer's disease, but more research must be done to confirm this early finding.

On the other hand, some studies have raised concerns about a link between estrogen and cancer of the uterus and a possible link between estrogen and breast cancer. It appears that estrogen given to women after menopause also increases the risk of blood clots. Heart attacks, strokes, and other circulation problems may result from blood clots.

Although much is known about estrogen, scientists are learning more. For example, a recent study suggests that older women whose bones are found to be at lower risk of osteoporosis may be at higher risk of breast cancer (doctors can predict a woman's likelihood of developing osteoporosis by measuring bone mineral density). Researchers think this increased breast cancer risk may occur in some women whose bodies have produced high amounts of natural estrogen over their lifetime. More research is needed to tell whether estrogen supplements alone increase the risk of breast cancer.
Researchers have studied estrogen for many years. As a result, doctors are better informed about which women are likely to benefit from supplements and about the right doses to prescribe so that the risk of side effects is reduced. Adding progestin, another female hormone, to estrogen supplements lowers risk of uterine cancer.

The decision whether or not to take estrogen is a personal one. Each woman, along with her doctor, should ask herself: Is there heart disease in my family? Or breast cancer? What are the results of my bone mineral density measurement? Have I had blood clots before, or has my doctor told me that I am prone to blood clots?

There is no right or wrong answer to these questions. Each woman must weigh her answers, based on her health history, with her doctor.

Trophic factors are substances that help control the growth and repair of our tissues and organs throughout our lives. Some trophic factors are considered hormones. Researchers are studying them to find out if decreasing levels of these factors are responsible, at least in part, for the diseases and disabilities seen in aging. Now in its fourth year, a group of 5-year studies of trophic factors is under way. Testosterone, estrogen, and growth hormone are included in the study.

It is important to remember that these studies may not give immediate or final answers, especially in the case of DHEA, melatonin, and human growth hormone, since research on these supplements is fairly new. For example, some of the studies may simply give researchers more information about what kinds of questions they should ask in their next studies. Research is a step-by-step process, and larger studies may be needed to give more definite answers.

Until more is known about DHEA, melatonin, and hGH, consumers should view them with a good deal of caution—and doubt. Despite what advertisements or stories in the media may claim, hormone supplements have not been proven to prevent aging. Some harmful side effects already have been discovered, and further research may uncover others.

More is known about estrogen and testosterone, and people who are concerned about genuine deficiencies of these hormones should consult with their doctors about supplements. Meanwhile, people who choose to take any hormone supplement without a doctor's supervision do so at their own risk.