Boning Up on Osteoporosis
Consider an insidious condition that drains away bone--the hardest, most durable
substance in the body. It happens slowly, over years, so that often neither
doctor nor patient is aware of weakening bones until one snaps unexpectedly.
Unfortunately, this isn't science fiction. It's why osteoporosis is called the
And it steals more than bone. It's the primary cause of hip fracture, which
can lead to permanent disability, loss of independence, and sometimes even death.
Collapsing spinal vertebrae can produce stooped posture and a "dowager's hump."
Lives collapse too. The chronic pain and anxiety that accompany a frail frame
make people curtail meaningful activities because, in extreme cases, the simplest
things can cause broken bones: Stepping off a curb. A sneeze. Bending to pick
up something. A hug. "Don't touch Mom, she might break" is the sad joke in many
Osteoporosis leads to 1.5 million fractures, or breaks, per year, mostly in
the hip, spine and wrist, with the cost of treatment estimated at $17 billion
and rising, according to the National Institutes of Health (NIH). It threatens
34 million Americans, mostly older women, but older men get it too. One in 2
women and 1 in 4 men older than 50 will suffer a vertebral fracture, according
to the NIH. These numbers are predicted to rise as the population ages.
Osteoporosis, which means "porous bones," is a condition of excessive skeletal
fragility resulting in bones that break easily. A combination of genetic, dietary,
hormonal, age-related, and lifestyle factors all contribute to this condition.
The osteoporosis seen in postmenopausal women is the most common and best-studied,
but there are other causes that may be treated differently.
Changing attitudes and improving technology are brightening the outlook for
people with osteoporosis. Nowadays, many women live 30 years or more--perhaps
a quarter to a third of their lives--after menopause. Improving the quality
of those years has become an important health care goal. Although some bone
loss is expected as people age, osteoporosis is no longer viewed as an inevitable
consequence of aging. Diagnosis and treatment need no longer wait until bones
There is no cure or proven preventive treatment for osteoporosis, but the onset
can be delayed and the severity diminished. Most important, early intervention
can prevent devastating fractures. The Food and Drug Administration has revised
labeling on foods and supplements to provide valuable information about the
level of nutrients that help build and maintain strong bones. The FDA has also
approved a wide variety of products to help diagnose and treat osteoporosis,
including several in the last few years.
Osteoporosis has been described as a geriatric disease with an adolescent onset,
highlighting the importance of beginning to take steps--in exercise and diet--early
in life to reduce its disabling impact in later years.
Bone consists of a matrix of fibers of the tough protein collagen, hardened
with calcium, phosphorus and other minerals. Two types of architecture give
bones strength. Surrounding every bone is a tough, dense rind of cortical bone.
Inside is spongy-looking trabecular bone. Its interconnecting structure provides
much of the strength of healthy bone, but it is especially vulnerable to osteoporosis.
"We tend to think of the skeleton as an inert erector set that holds us up
and doesn't do much else. That's not true," says Karl L. Insogna, M.D., director
of the Bone Center at Yale School of Medicine in New Haven, Conn. Every bit
as dynamic as other tissues, bone responds to the pull of muscles and gravity,
repairs itself, and constantly renews itself.
Besides protecting internal organs and allowing us to move about, bone is also
involved in the body's handling of minerals. Of the 2 to 4 pounds of calcium
in the body, nearly 99 percent is in the teeth and skeleton. The remainder plays
a critical role in blood clotting, nerve transmission, muscle contraction (including
heartbeat), and other functions. The body keeps the blood level of calcium within
a narrow range. When needed, bones release calcium.
A complex interplay of many hormones balances the activity of the two types
of cells--osteoclasts and osteoblasts--responsible for the continuous turnover
process called remodeling. Osteoclasts break down bone, and osteoblasts build
it. In youth, bone building prevails. Bone mass peaks by about age 30, then
bone breakdown outpaces formation, and density declines, since the volume of
bone remains about the same.
The skeleton is like a retirement account for minerals, but in our skeletal
"account" we can deposit bone faster than we withdraw it only during our first
three decades. After that, withdrawals are greater than deposits, and all we
can do is try to minimize the net loss. Osteoporotic fractures are the sign
of the bankruptcy that occurs when too little bone is formed during youth, or
too much is lost later, or both.
"You've got to get as much bone as you can and not lose it," Insogna says.
"The most important risk factor for osteoporosis is a low bone mass."
"The upper limit of bone mass that you can acquire is genetically determined,"
says Mona S. Calvo, Ph.D., a calcium expert in the FDA's Center for Food Safety
and Applied Nutrition. "But even though you may be programmed for high bone
mass, other factors can influence how much bone you end up with," she says.
For instance, men tend to build greater bone mass, which is partly why more
women face osteoporosis.
But there's another reason. With the decline of the female hormone estrogen
at menopause, usually around age 50, bone breakdown markedly increases. For
several years, women lose bone two to four times faster than they did before
menopause. The rate usually slows down again, but some women may continue to
lose bone rapidly. By age 65, some women have lost half their skeletal mass.
Because the changes at menopause increase a woman's risk, many physicians feel
it's a good time to measure a woman's bone mineral density, especially if she
has other risk factors for osteoporosis.
"The best way to gauge a woman's risk for osteoporotic fracture is to measure
her bone mass," says Insogna.
Routine X-rays can't detect osteoporosis until it's quite advanced, but other
radiological methods can. The FDA has approved several kinds of devices that
use various methods to estimate bone density. Most require far less radiation
than a chest X-ray. Doctors consider a patient's medical history and risk factors
in deciding who should have a bone density test. The method used is often determined
by the equipment available locally. Readings are compared to an internationally
accepted standard based on young Caucasian women. Different parts of the skeleton
may be measured, and low density at any site is worrisome.
Bone density tests are useful for confirming a diagnosis of osteoporosis if
a person has already had a suspicious fracture, or for detecting low bone density
so that preventive steps can be taken.
"There's a profound relationship between bone mass and risk of fracture," says
Robert Recker, M.D., director of the Osteoporosis Research Center at Creighton
University in Omaha, Neb.
Readings repeated at intervals of a year or more can determine the rate of
bone loss and help monitor treatment effectiveness. However, estimates are not
necessarily comparable between machine types because they use different measurement
methods, cautions Joseph Arnaudo, in the FDA's Center for Devices and Radiological
Health. "You always want to go back to the same machine, if you can," he says.
A newer technique for evaluating bone strength is ultrasound, and the FDA has
approved several instruments for this purpose. "These machines use the same
principles that are employed when using ultrasound to look at fetuses during
pregnancy," says Leo Lutwak, M.D., Ph.D., of the FDA's Division of Reproductive,
Abdominal, and Radiological Devices. "Although this measurement examines different
properties of bone than do X-ray-based bone densitometers, the results are also
useful for prediction of fracture." The devices for ultrasound measurement are
cheaper and easier to use. This makes them available in more locations and allows
evaluation for osteoporosis in many more subjects. "Because they don't use X-rays,
they are safer and may be used for repeated examinations, even in pregnant women
and children, so they provide a means for better public health practice," Lutwak
Another new test provides an indicator of bone breakdown. In 1995, the FDA
approved a simple, noninvasive biochemical test that detects in a urine sample
a specific component of bone breakdown, called NTx. Clinical labs can get results
in about 2 hours. The NTx test, marketed as Osteomark, can help physicians monitor
treatment and identify fast losers of bone for more aggressive treatment, but
the test doesn't measure bone metabolism specifically, so it may not be used
to diagnose osteoporosis.
Expanding Treatment Options
Physicians and patients now have more treatment options. Under FDA guidelines,
drugs to treat osteoporosis must be shown to preserve or increase bone mass
and maintain bone quality in order to reduce the risk of fractures.
An important treatment option became available to women in November 2002. Forteo
(teriparatide) is the first treatment that stimulates new bone growth to increase
bone mass. Forteo is a portion of human parathyroid hormone, which works in
the body to regulate the metabolism of calcium and phosphate in bones. The treatment
is given in daily injections and is approved for postmenopausal women who are
at high risk for bone fractures.
The approval of this treatment comes with a strong caution from the FDA: In
the pre-approval studies of Forteo using rats, there was an increase in the
incidence of osteosarcoma, a rare but serious cancer of the bone. Because it's
possible that women treated with Forteo could have increased risk for developing
this cancer, doctors are advised to discuss this risk with their patients and
be sure that it's the best treatment. Women who are prescribed Forteo receive
an FDA-approved medication guide that explains the benefits and risks and gives
other advice about how to use the treatment properly.
All other drugs approved for osteoporosis treatment act by slowing the turnover
of bone, rather than stimulating new bone formation. Increases in bone mass
are most pronounced in the first year or two after treatment with the drugs
begins, then taper off. Any gain is helpful, even if it doesn't continue, because
increases in bone mass help reduce fracture risk.
In the mid-1990s, the FDA approved the first nonhormonal treatment for osteoporosis.
Alendronate, marketed as Fosamax, falls within a class of drugs called bisphosphonates.
In clinical trials, Fosamax increased the bone mass as much as 8 percent and
reduced fractures as much as 30 percent to 40 percent, depending on skeletal
To avoid damage to the esophagus, Fosamax should be taken according to the
instructions. These instructions include taking the drug in the morning upon
awaking and at least half an hour before eating. The drug should be taken with
a glass of water, and the person should remain upright for half an hour after
taking it. Fosamax should not be taken by people who cannot stand or sit upright
or who have disorders that prevent esophageal emptying into the stomach.
Other drugs recently approved for the prevention and treatment of osteoporosis
are Actonel (risedronate), a bisphosphonate similar to Fosamax, and Evista (raloxifene),
a drug in a class known as selective estrogen receptor modulators, or SERMs.
Both drugs have been shown to reduce the risk for fracture of the spine.
Calcitonin is a hormone that plays a role in calcium and bone metabolism. When
used regularly, it can slow the loss of bone. Available for many years as an
injection, calcitonin treatment became much easier when FDA approved a nasal
Fluoride, known for fighting dental cavities, stimulates bone building, but
studies in osteoporosis patients have found that the structure of the new bone
was abnormal and weaker than normal bone.
While estrogen may be a good option for some women, new guidelines developed
in 2003 by the FDA advise doctors to consider alternative treatments. These
changes were prompted by studies indicating that women who take estrogen or
estrogen with progestin products after menopause are at higher risk for other
conditions, including cardiovascular disease and breast cancer. Because of this,
estrogen-containing products should only be considered for women at significant
risk of osteoporosis.
Drugs Not Enough
Calcium and vitamin D supplements are an integral part of all treatments for
osteoporosis. At the same time, people who take supplements should keep in mind
that it is possible to consume excess amounts of these and other nutrients.
Attention to diet and exercise are important not only for treatment, but also
"If you go to the doctor and get a prescription, and that's all you do, you're
probably not going to be helped very much," Recker says.
Calcium intake is critical, and those who need it most--younger women and girls--may
not get enough. (See "Calcium (Ac)Counts.") But calcium
alone can't build bones. Vitamin D is needed to help the body absorb calcium.
Most people appear to get enough vitamin D because the skin produces it in sunlight.
And many foods, such as milk products and breakfast cereals, are fortified with
vitamin D. But older adults and people with little exposure to sunlight may
need a vitamin D supplement.
A lifelong habit of weight-bearing exercise, such as walking or biking, also
helps build and maintain strong bone. The greatest benefit for older people
is that physical fitness reduces the risk of fracture, because better balance,
muscle strength, and agility make falls less likely. Exercise also provides
many other life-enhancing psychological and cardiovascular benefits. Increased
activity can aid nutrition, too, because it boosts appetite, which is often
reduced in older people. The biggest reason older people don't get enough calcium,
Recker says, is that they simply don't eat much.
"The truth is, you don't have to do very much to get most of the benefits of
exercise," Recker says. He suggests 30 minutes of brisk walking five days a
week. Add a little weightlifting, and that's even better. It's always smart
to ask your doctor before starting a new exercise program, especially if you
already have osteoporosis or other health problems.
The search for bone-building drugs continues. Some naturally occurring bone-specific
growth factors have been identified and their use as drugs is being investigated.
"The way I visualize the ideal future is that we'll be able to give Drug X that
builds up bone to where it's stronger and the risk of fracture is no longer
present, then Drug Y maintains it by preventing breakdown," says Paula Stern,
Ph.D., a pharmacologist at Northwestern University Medical School in Chicago.
The study of risk factors also continues. "We consider that to be the research
that has the greatest public health significance," says Sherry Sherman, Ph.D.,
of the National Institute on Aging.
Reducing Your Risk
Many factors can affect your chances of developing osteoporosis. The good
news is that you control some of them. Even though you can't change your genes,
you can still lower your risk with attention to certain lifestyle changes that
will help build and maintain bone mass. The younger you start, and the longer
you keep it up, the better.
Here's what you can do for yourself:
- Be sure you get enough calcium and vitamin D.
- Engage in regular physical activity, such as walking.
- Don't smoke.
- If you drink alcohol, do so in moderation.
A sedentary lifestyle, smoking, excessive drinking, and low calcium intake
all increase risk.
Other factors are beyond your control. Being aware of them can provide extra
motivation and can help you and your doctor to make health care decisions. These
risk factors are:
- being female
Women are at five times greater risk than men.
- thin, small-boned frame
- broken bones or stooped posture in older family members, especially women,
which suggest a family history of osteoporosis
- early estrogen deficiency in women who experience menopause before age 45,
either naturally or resulting from surgical removal of the ovaries
- estrogen deficiency due to abnormal absence of menstruation (as may accompany
- ethnic heritage
White and Asian women are at highest risk; African-American and Hispanic women
are at lower, but significant, risk.
- advanced age
- prolonged use of some medications
These medications include some antiseizure medications, glucocorticoids (certain
anti-inflammatory medications, such as prednisone, used to treat asthma, arthritis
and some cancers), certain cancer treatments, some treatments for endometriosis,
excessive use of aluminum-containing antacids, and excessive thyroid hormone.
It is important to discuss the use of these drugs with your physician, and
not to stop or alter your medication dose on your own.
- growth hormone deficiency in children and youth.
Risk factors may not tell the whole story. You may have none of these factors
and still have osteoporosis. Or you may have many of them and not develop the
condition. It's best to discuss your specific situation with your doctor.
Your skeletal calcium bank has to last through old age. Frequent deposits to
this retirement account should begin in youth and be maintained throughout life
to help minimize withdrawals. Recommendations for daily calcium intakes were
established a few years ago by the Institute of Medicine.
Nutritionists recommend meeting your calcium needs with foods naturally rich
in calcium. Adequate calcium intake in childhood and young adulthood is critical
to achieving peak adult bone mass, yet many adolescent girls replace milk with
nutrient-poor beverages like soda pop. "Bone health requires a lot of nutrients
and you're likely to get most of them in dairy products," says Connie Weaver,
Ph.D., who heads the department of foods and nutrition at Purdue University.
"They're a huge package rather than just a single nutrient." With so many low-fat
and nonfat dairy products available, it's easy to make dairy foods part of a
healthy diet. People who have trouble digesting milk can look for products treated
to reduce lactose. A serving of milk or yogurt contains about 350 milligrams
of calcium. Fortified products have even more.
"People who don't consume dairy foods can meet their calcium needs with foods
that are fortified with calcium, such as orange juice, or with calcium supplements,"
says Mona S. Calvo, Ph.D., a calcium expert in the FDA's Center for Food Safety
and Applied Nutrition. Other good sources of calcium are dark-green leafy vegetables
like kale and turnip greens, tofu (if made with calcium), canned fish (eaten
with bones), and fortified cereal products.
The food label can help you identify foods that are a good source of calcium
and other nutrients important for bone health, such as vitamin D. You can use
the Nutrition Facts found on the label to see if a food is a good source of
these nutrients--that is, if it has at least 10 percent of the Daily Value (DV)
per serving. Also, if a food has at least 10 percent of the DV, the label may
bear a claim that it is a good source of a nutrient. If it has 20 percent or
more, the label can say that it is "high" in or an "excellent source." Some
foods that are excellent sources of calcium may also bear a health claim about
the role of diet and other factors in reducing the risk of osteoporosis.
But keep in mind that foods with smaller amounts (such as between 5 percent
and 10 percent of the DV) can still make significant contributions to your daily
calcium intake. This may be especially true if you often eat more than one serving
of the food in a day, or if your actual serving size is typically larger than
the one on the label.
Finally, remember that label values are based on a single Daily Value established
by the FDA for food labeling purposes--1000 milligrams in the case of calcium.
They do not take into account that some age groups have lower or higher recommendations
What about too much calcium? A few years ago, the Institute of Medicine established
a level of 2,500 milligrams as an upper intake level for calcium for most people.
While intakes considerably above this level may be safe for many, others may
be particularly susceptible to calcium's potentially harmful effects at these
levels. Those with higher sensitivities, such as people at risk of kidney stones,
should discuss calcium with their doctors.
Calcium is critical, but even a high intake won't fully protect you against
bone loss caused by estrogen deficiency, physical inactivity, alcohol abuse,
smoking, or medical disorders and treatments.
How Much Calcium Do You Need?
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