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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.
The National Institute
on Aging (NIA), part of the National Institutes of Health, conducts research
to find out how hormone supplements affect people. In the case of most
hormone supplements, it is not yet known how much is too much or too little,
and for some, whether hormone supplements should be taken at all. This
fact sheet provides information about what is known so far and about what
researchers are doing to find out more.
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
testos-terone 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 percent 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 meas-urement?
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.
Studies Under Way
The NIA sponsors many
research projects that will reveal more about the risks and benefits of
hormone supplements. One goal is to dis-cover how DHEA, melatonin, and
other supplements affect people over time.
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.
See also the "Media
Campaign Cautions Consumers About 'Anti-aging Hormone Supplements'"
press release.
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