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Pills,
Patches, and Shots:
Can Hormones Prevent Aging?
We could not survive without hormones. They are among the most
common and vital chemical messengers in the body. From head
to toe, each moment of life, they signal cells to perform tasks
that range from the ordinary to the extraordinary. Among their
many roles, hormones help regulate body temperature, blood pressure,
and blood sugar levels. In childhood, they help us “grow
up.” In the teen years, they are the driving force behind
puberty. But what influence, if any, the natural decline in
some hormones has on the aging process in middle and late life
is unclear. Although a few proponents are convinced that hormone
supplements can favorably alter the aging process and have advocated
their widespread use, the scientific evidence supporting this
premise is, for the most part, sketchy.
For more than a decade, the National Institute on Aging (NIA),
a component of the federal government’s National Institutes
of Health, has supported and conducted studies of replenishing
hormones and similar substances to find out if they may help
reduce frailty and improve function in older people. These studies
have focused on hormones known to decline as we grow older:
- Dehydroepiandrosterone (DHEA)
- Growth Hormone
- Melatonin
- Testosterone
- Menopausal hormones, such as estrogen
The results from these NIA-sponsored studies and other research
projects likely will improve our understanding of the pros and
cons of hormone supplementation. Until the results of these
studies are compiled, analyzed, and a consensus among scientists
is reached, recommendations to use supplemental hormones and
hormone-like molecules to influence the aging process and health
problems associated with aging should be viewed with skepticism.
It is not yet known, for instance, how much is too much or too
little, and when or whether hormone supplements should be taken
at all. This fact sheet provides information about what is known
so far and what researchers are doing to find out more.
What Is A Hormone?
Hormones are powerful chemicals that help keep our bodies working
normally.
The term hormone is derived from the Greek word, hormo, which
means to set in motion. And that’s precisely what hormones
do in the body. They stimulate, regulate, and control the function
of various tissues and organs. Made by specialized groups of
cells within structures called glands, hormones are involved
in almost every biological process including sexual reproduction,
growth, metabolism, and immune function. These glands, including
the pituitary, thyroid, adrenals, ovaries and testes, release
various hormones into the body as needed.
Levels of some hormones like parathyroid hormone, which helps
regulate calcium levels in the blood and bone, actually increase
as a normal part of aging and may be involved in bone loss leading
to osteoporosis. But the levels of a number of other hormones,
such as testosterone in men and estrogen in women, tend to decrease
over time. In other cases, the body may fail to make enough
of a hormone due to diseases and disorders that can develop
at any age. When this occurs, hormone supplements—pills,
shots, topical (rub-on) gels, and medicated skin patches—may
be prescribed.
Unproven claims that taking hormone supplements can make people
feel young again or that they can slow or prevent aging have
been “hot” news items for several years. The reality
is that no one has yet shown that supplements of these hormones
prevent frailty or 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. In any case, people who have diagnosed hormone
deficiencies should take them only under a doctor’s supervision.
Remember: More is not necessarily better. The right balance
of hormones helps us stay healthy, but the wrong amount might
be damaging.
Heed The Warnings
The NIA recognizes that some hormone-like products are available
over the counter and can be used without consulting a physician.
The Institute discourages individuals from self-medicating with
these products for a number of reasons. First, these products
are marketed as “dietary supplements”, and therefore
are not regulated by the Food and Drug Administration in the
same way as drugs. This is an important distinction because
the requirements for marketing a dietary supplement are very
different from those that apply to hormones marketed as drugs.
Unlike drug manufacturers, a firm selling dietary supplements
doesn’t need FDA approval of its products and doesn’t
need to prove that its products are safe and effective before
marketing. Also, there is no specific guarantee that the substance
in the container is authentic or that the indicated dosage is
accurate. Because of these differing standards, hormone-like
substances that are sold as dietary supplements may not be as
thoroughly studied as drug products, and, therefore, the potential
consequences of their use are not well understood or known.
In addition, these over-the-counter products may interfere with
other medications you are taking.
Therefore, the NIA does not recommend taking any supplement,
including DHEA and melatonin that is touted as an “anti-aging”
remedy because no supplement has been proven to serve this purpose.
The influence of these supplements on a person’s health
is unknown, particularly when taken over a long period of time.
Talk to your doctor if you are interested in any form of hormone
supplementation. In fact, you might want to show this fact sheet
to your doctor to help explain your concerns.
How Hormones Work
Most hormones exist in very low concentrations in the bloodstream.
Each hormone molecule travels through the blood until it reaches
a cell with a receptor that it matches. Then, the hormone molecule
latches onto the receptor and sends a signal into the cell.
These signals may instruct the cell to multiply, to make proteins
or enzymes, or to perform other vital tasks. Some hormones can
even stimulate a cell to release other hormones. However, no
single hormone affects all cells in the same way. One hormone,
for example, may stimulate a cell to perform one task, while
the same hormone can have an entirely different influence over
another cell. The response of some cells to hormonal stimulation
also may change throughout life.
Hormone supplements, particularly if taken without medical
supervision, may adversely affect this complex system. These
supplements, for instance, may not behave exactly the same way
as our own naturally produced hormones have because the body
may process them differently. In addition, natural hormone production
isn’t constant, so circulating blood levels may vary significantly
over a 24-hour period. Hormone supplements can’t replicate
these fluctuations. As a result, high doses of supplements,
whether pills, gels, skin patches, or shots, may result in excessive
and unhealthy amounts of hormones in the blood. Hormone supplements
also may compound any negative effects caused by hormones naturally
produced by the body.
Finally, most of the processes in the body are tightly controlled
and regulated. Too much stimulation can elicit natural responses
to inhibit a hormone’s action. The body’s system
of checks and balances is complicated and the notion that hormone
supplements can improve function may be an oversimplification.
DHEA
Dehydroepiandrosterone or DHEA is made from cholesterol by
the adrenal glands, which sit on top of each kidney. Production
of this substance peaks in the mid-20s, and gradually declines
with age in most people. What this drop means or how it affects
the aging process, if at all, is unclear. In fact, scientists
are somewhat mystified by DHEA and have not fully sorted out
what it does in the body. However, researchers do know that
the body converts DHEA 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
are sold as “anti-aging remedies.” Some proponents
of these products claim that DHEA supplements improve energy,
strength, and immunity. DHEA is also said to increase muscle
and decrease fat. Right now there is no consistent evidence
that DHEA supplements do any of these things in people, and
there is little scientific evidence to support the use of DHEA
as a “rejuvenating” hormone. Although the long-term
(over one year) effects of DHEA supplements have not been studied,
there are early signs that these supplements, even when taken
briefly, may have several detrimental effects on the body including
liver damage.
In addition, some people's bodies make more estrogen and testosterone
from DHEA than others. 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. This is important because testosterone may play
a role in prostate cancer, and higher levels of estrogen are
associated with an increased risk of breast cancer. 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 can
cause acne and 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 in older people 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) is made by the pituitary gland,
a pea-sized structure located at the base of the brain, and
is important for normal development and maintenance of tissues
and organs. It is especially important for normal growth in
children.
Studies have shown that injections of supplemental hGH are
helpful to certain people. Sometimes children are unusually
short because their bodies do not make enough hGH. When they
receive injections of this hormone, 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 hGH, they lose weight.
Like some other hormones, blood levels of hGH often decrease
as people age, but this may not necessarily be bad. At least
one epidemiological study, for instance, suggests that people
who have high levels of hGH are more apt to die at younger ages
than those with lower levels of the hormone. Studies of animals
with genetic disorders that suppress growth hormone production
and secretion also suggest that reduced growth hormone secretion
may prolong survival in some species.
Although there is no conclusive evidence that hGH can prevent
aging, some people spend a great deal of money on supplements.
These supplements are claimed, by some, to increase muscle,
decrease fat, and to boost an individual’s stamina and
sense of well being. Shots—the only proven way of getting
the body to make use of supplemental hGH —can cost more
than $15,000 a year. They are available only by prescription
and should be given by a doctor. In any case, people in search
of the "fountain of youth" may have a hard time finding
a doctor who will give them shots of hGH because so little is
known about the long-term risks and benefits of this controversial
treatment. Some dietary supplements, known as human growth hormone
releasers, are marketed as a low-cost alternative to hGH shots.
But claims that these over-the-counter products retard the aging
process are unsubstantiated.
While some studies have shown that supplemental hGH does increase
muscle mass, it seems to have little impact on muscle strength
or function. Scientists are continuing to study hGH, but they
are watching their study participants very carefully because
side effects can be serious in older adults. These 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. A recent report that
treatment of children with human pituitary growth hormone increases
the risk of subsequent cancer is a cause for concern. Further
studies on this issue are needed. Whether older people treated
with hGH for extended periods have an increased risk of cancer
is unknown.
For now, there is no convincing evidence hGH supplements will
improve the health of those who do not suffer a profound deficiency
of this hormone.
Melatonin
This hormone is made by the pineal gland, a structure in the
brain. Contrary to the claims of some, secretion of melatonin
does not necessarily decrease with age. Instead, a number of
factors, including light and many common medications, can affect
melatonin secretion in people of any age.
Melatonin supplements 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 oxygen-related
molecules that cause damage to the body). Early test-tube studies
suggested that, in large doses, melatonin might be effective
against free radicals. 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
our daily sleep/wake cycle, and that supplements, in amounts
ranging from 0.1 to 0.5 milligrams, can improve sleep in some
cases. If melatonin is taken at the wrong time, though, it can
disrupt the sleep/wake cycle. Other side effects may include
confusion, drowsiness, and headache the next morning. Animal
studies suggest that melatonin may cause some blood vessels
to constrict, a condition that could be dangerous for people
with high blood pressure or other cardiovascular problems.
These side effects are important to keep in mind since the
dose of melatonin usually sold in stores - 3 milligrams - can
result in amounts in the blood from 10 to 40 times higher than
normal. What long -term effects such high concentrations of
melatonin may have on the body are still unknown. Until researchers
find out more, caution is advised.
Testosterone
Ask an average man about testosterone, and he might tell you
that this hormone helps transform a boy into a man. Or, he might
tell that you that it has “something” to do with
sex drive. Or, if he has read news stories in recent years,
he might mention “male menopause,” a condition supposedly
caused by diminishing testosterone levels in aging men. In reality,
there is scant evidence that this controversial condition, also
known as “andropause” or “viropause,”
exists.
Testosterone is indeed a vital sex hormone that plays an important
role in puberty. But contrary to what some people believe, testosterone
isn’t exclusively a male hormone. Women produce small
amounts of it in their bodies as well. In men, testosterone
is produced in the testes, the reproductive glands that also
produce sperm. The amount of testosterone produced in the testes
is regulated by the hypothalamus and the pituitary gland.
As men age, their testes often produce somewhat less testosterone
than they did during adolescence and early adulthood, when production
of this hormone peaks. But it is important to keep in mind that
the range of normal testosterone production is large. So while
there are some declines in testosterone production with age,
most older men stay well within normal limits, and the likelihood
that a man will ever experience a major shut down of hormone
production similar to a woman's menopause, is remote.
In fact, many of the changes that take place in older men often
are incorrectly blamed on decreasing testosterone levels. Some
men who have erectile difficulty (impotence), for instance,
may be tempted to blame this problem on lowered testosterone.
However, in the vast majority of cases, erectile difficulties
are due to circulatory problems, not low testosterone.
Still, a small percentage of men may be helped by testosterone
supplements. These supplements are prescribed for men whose
bodies make very little or no testosterone—for example,
men whose pituitary glands have been destroyed by infections
or tumors, or whose testes have been damaged. For these few
men who have extreme testosterone deficiencies, supplements
in the form of patches, injections, or topical gel may offer
substantial benefit. Supplements may help a man with exceptionally
low testosterone levels maintain strong muscles and bones, and
increase sex drive. However, what effects testosterone replacement
may have in healthy older men without these extreme deficiencies
requires more research.
The NIA is investigating the role of testosterone supplementation
in delaying or preventing frailty. Results from preliminary
studies involving small groups of men have been inconclusive,
and it remains unclear to what degree supplementation of this
hormone can sharpen memory or help men maintain stout muscles,
sturdy bones, and robust sexual activity.
Many other questions remain about the use of this hormone in
late life. It is unclear, for example, whether men who are at
the lower end of the normal range of testosterone production
would benefit from supplementation. Some investigators are also
concerned about the long-term harmful effects that supplemental
testosterone might have on the aging body. It is not yet known,
for instance, if testosterone supplements increase the risk
of prostate cancer, the second leading cause of cancer death
among men. In addition to potentially promoting new prostate
cancers, testosterone also may promote the growth of those that
have already developed. Studies also suggest that supplementation
might trigger excessive red blood cell production in some men.
This side effect can thicken blood and increase a man's risk
of stroke.
The bottom line: Although some older men who have tried these
supplements report feeling "more energetic" or "younger,”
testosterone supplementation remains a scientifically unproven
method for preventing or relieving any physical and psychological
changes that men with normal testosterone levels may experience,
as they get older. Until more scientifically rigorous studies
are conducted, the question of whether the benefits of testosterone
replacement outweigh any of its potential negative effects will
remain unanswered.
Menopausal Hormones
Unlike other hormones described in this fact sheet, many large,
reliable, long-term studies of estrogen and its effects on the
body have been conducted. These studies suggested that estrogen
could provide many important benefits. Based on this early research
many women were advised to take supplements of estrogen to relieve
the symptoms of menopause and to reduce their risk of osteoporosis
and heart disease.
But estrogen also is a good example of why it is important to
wait until researchers have discovered both the benefits and
risks of a hormone supplement before it becomes widely used.
While some women are helped by estrogen during and after menopause,
others are placed at higher risk for certain diseases if they
take it. As research yields new information about this hormone,
women and their doctors continue to reevaluate their thinking
about who should take estrogen supplements and who should not.
For many women, the helpful effects of estrogen might outweigh
the possible harmful effects when taken relatively briefly around
the time of menopause. Estrogen supplements decrease hot flashes
and vaginal dryness, and lower the risk for osteoporosis, a
bone-thinning disease that often disables older people. Estrogen
therapy also may improve mood and psychological well-being.
Yet for all of its promise, estrogen supplementation also has
raised a number of serious concerns because some harmful effects
are more likely to occur in certain women. For example, estrogen
is associated with an increased risk of cancer of the uterus
among women who have not had a hysterectomy. To counteract this
risk, a woman with a uterus is advised to take progestin, a
synthetic form of the hormone progesterone, with their estrogen.
Using estrogen alone or with progestin is called menopausal
hormone therapy (MHT). Early studies suggested menopausal hormone
therapy could lower the risk for heart disease (the number-one
killer of women in the U.S.) in postmenopausal women. But subsequent
research now suggests that such therapy might actually elevate
some women’s chances of developing this disease. Menopausal
hormone therapy also increases a woman’s risk of getting
blood clots, which can block circulation in arteries and could
lead to heart attack or stroke.
In 2002, an important study of menopausal hormone therapy by
the Women’s Health Initiative, which is funded by the
National Institutes of Health, was stopped after 5.2 years because
serious health concerns arose. The investigators found that
among every 10,000 women taking a combination of progestin and
estrogen, there would be:
- 8 more cases of breast cancer than in women not using any
hormones, which translates into a 26 percent increased risk,
- 7 more cases of heart disease (a 29 percent increased risk),
- 8 more cases of stroke (a 41 percent increased risk), and
- 8 more women who developed blood clots in their lungs, which
is twice the rate occurring among women not taking any hormones.
But there also would be health benefits:
- 5 fewer cases of hip fracture (a 34 percent reduced risk),
and
- 6 fewer cases of colorectal cancer (a 37 percent reduced
risk).
The study was stopped early because the experts believed that
by that time the health risks were greater than the health benefits.
These risks are still small ones for an individual woman, but
it is an important public health issue. The portion of the study
looking at hysterectomized women using only estrogen without
progestin did not find similar risks, so it will continue.
Some studies suggest that estrogen may protect against Alzheimer's
disease, but this has not yet been proven. In fact, in 2003
a related study, the Women’s Health Initiative Memory
Study, reported that women age 65 and older taking a combination
of estrogen plus progestin were at twice the risk of developing
dementia as women not taking any hormones. This means that every
year there would be 23 additional cases of dementia in 10,000
women 65 and older taking these hormones compared to 10,000
women the same age not taking any hormones (a 105% increased
risk). As with the larger Women’s Health Initiative trial,
the estrogen alone portion of this study is continuing.
So the decision whether to take estrogen is now far more complex
and difficult. Although researchers have studied estrogen for
many years, numerous questions about this hormone—once
thought answered—are reemerging. Before choosing this
treatment, each woman, with the guidance and advice of her doctor,
should weigh the pros and cons of menopausal hormone therapy
and make an informed choice based on a realistic assessment
of her personal risks and benefits.
Keep in mind that even after years of intense study, researchers
continue to discover information about the benefits and risks
of these menopausal hormones. As these new findings emerge,
women and their doctors may have to frequently reassess their
decisions about these supplements.
Many Questions, Few Answers
The NIA sponsors many research projects that will reveal more
about the risks and benefits of hormone supplements. One goal
is to determine whether DHEA, melatonin, and other hormonal
supplements improve the health of older people, have no effect,
or are actually harmful.
It is important to remember that these studies may not give
immediate or final answers, especially in the cases of DHEA,
melatonin, and hGH, 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 definitive 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 should be aware that these supplements appear to
have few clear-cut benefits for healthy individuals, and no
proven influence on the aging process.
National Institute on Aging
U. S. Department of Health and Human Services
Public Health Service
National Institutes of Health
August 2003
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