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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
- 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.
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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
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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
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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.
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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
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.
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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
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.
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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.
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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),
- 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)
- 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.
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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.
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