Pills,
Patches, and Shots: Can Hormones Prevent
Aging?
article syndicated from NIA
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:
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
National Institutes of Health
August 2003