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What causes osteoporosis?
No single cause for osteoporosis has been identified. However, certain
factors - called risk factors - do seem to play a role in the development of the disease. Major risk factors
include:
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being 65 or older,
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having a family history of osteoporotic fracture (especially if your
mother had a hip fracture),
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having a vertebral compression fracture, or a fracture with minimal
trauma after age 40,
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long-term (more than 3 months) use of glucocorticoid therapy such as
prednisone,
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medical conditions (such as celiac or Crohn's disease) that inhibit
absorption of nutrients,
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primary hyperparathyroidism,
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tendency to fall,
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osteopenia apparent on x-ray,
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hypogonadism, and
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early menopause (before age 45).
Minor risk factors include:
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rheumatoid arthritis,
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hyperthyroidism,
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prolonged use of anticonvulsants,
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body weight less than 57 kg (125 lbs),
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present weight more than 10% below weight at age 25,
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low calcium intake,
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excess caffeine (consistently more than 4 cups a day of
coffee, cola, some energy drinks)
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excess alcohol (consistently more than 2 drinks a day),
and
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smoking.
Women are especially at risk because of the important role that estrogen
plays in keeping their bones healthy. At menopause, there is a gradual decline in ovarian function and a
consequent loss of estrogen production. As estrogen levels decline, loss of bone tissue begins. Rapid bone
loss at a rate of two to five percent a year can occur for the first five to 10 years after
menopause.
Osteoporosis Canada recommends that all postmenopausal women and men over
50 be assessed for risk factors for osteoporosis. (For more information on risk factors, click here )
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Do men get osteoporosis?
Although osteoporosis is more common in women, at least one in eight men
over 50 also has the disease. In fact, in Canada 20-30% of osteoporotic fractures occur in men. As with the
decline of estrogen levels in women, lower testosterone levels in men can lead to an increase in bone loss.
The decline is more gradual in men and is not universal. A Canadian osteoporosis study (CaMOS) has found that
25% of Canadian men have vertebral fractures, similar to rates found in women. For more information on men
and osteoporosis, click here .
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What is the difference between osteoporosis and
osteoarthritis?
Despite the fact that osteoporosis and osteoarthritis are completely
different conditions, they are frequently confused because the names are similar. Osteoporosis is a bone
disease. Osteoarthritis is a disease of the joints and surrounding tissue. Rheumatoid arthritis, an
inflammatory disease of the lining of the joints, is another common form of arthritis.
Osteoarthritis is a degenerative joint disease, which leads to the
thinning or destruction of the cartilage, causing painful irritation of the joints and adjacent bone tissue.
Bony growths may occur because of the abnormal rubbing together of bones.
Osteoarthritis:
- Most often affects the hips, knees, fingers, feet or spine
- Can be painful
- Can be attributed to factors such as heredity, obesity and overuse or
injury of joints
Individuals who suffer from both arthritis and osteoporosis should plan a
program to manage both diseases. Specifically, they must pay attention to the advice they receive about
exercising. Individuals in this situation should seek the advice of a healthcare professional.
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My doctor tells me that I am at
risk for fracture. What are the risks?
The 2002 clinical practice guidelines for the diagnosis and management of
osteoporosis in Canada identify four key risk factors for fracture related to osteoporosis:
1. low bone mineral density
2. prior fragility fracture (fracture with little trauma)
3. age - the risk of fracture increases with age
4. family history of osteoporotic fracture
Bone mineral density (BMD) is the most readily quantifiable predictor of
fracture risk for those who have not yet suffered a fragility fracture. The 2002 clinical practice guidelines
recommend that anyone over age 65 should have a BMD test and anyone age 50 or older with one major or two or
more minor risk factors should have a BMD test.
Other risks for fracture are a tendency to fall and long-term
glucocorticoid use.
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Why is calcium nutrition so
important?
Calcium is important for building strong bones in childhood, maintaining
bone density in adulthood and reducing the risk of fracture as we age. In fact, every cell in our body needs
calcium to function properly. Because calcium is so important, our body carefully regulates blood levels of
calcium to ensure that calcium levels stay within the normal range. When blood levels of calcium are lower
than the range allows, calcium is removed from bone to raise these levels back to normal range. Conversely,
when blood calcium levels are above the range, as after a calcium-rich meal, calcium is deposited in the
bone. Therefore, bones act as a "calcium bank" with deposits and withdrawals being made according to a
strictly regimented system.
It is important to make sure you are getting the recommended amount of
calcium every day - from food sources, if possible. Because Vitamin D is crucial to calcium absorption, it is
also important to get the required amounts of Vitamin D. Osteoporosis Canada recommends the following intake
of calcium and Vitamin D every day to maintain strong bones:
| Age |
Calcium Requirement
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Vitamin D Requirement
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| 4-8 |
800 mg
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200 IUs
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| 9-18 |
1300 mg
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200 IUs
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| 19-50 |
1000 mg
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400 IUs
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| 50+ |
1500 mg
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800 IUs
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Pregnant or
lactating women 18+ |
1000 mg
|
400 IUs
|
(For more information on calcium, click here )
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My doctor tells me that I should decrease my
caffeine intake. Why?
Caffeine can contribute to calcium loss through the kidneys. Up to four
caffeine drinks per day are not considered to be detrimental providing there is adequate calcium intake.
Beyond this amount, decaffeinated beverages are recommended, or add extra calcium to counteract the effect of
caffeine. Caffeine is contained in coffee, tea, chocolate some soft drinks like cola beverages and some
energy drinks. Tea has an insignificant impact on caffeine intake.
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How do I choose a calcium
supplement?
Supplements are advisable for individuals who are not getting enough
calcium from food sources and are unable to make changes in their diet. There are many types of calcium
supplements on the market, with the most popular being calcium carbonate.
Look for a product where the label states the amount of elemental calcium
per tablet, eg., 1000 mg of calcium carbonate contains 400 mg of elemental calcium.
Look for products with a Drug Identification Number (DIN),
Natural Product Number (NPN) or General Product (GP) number. This indicates that the product meets
the Canadian standards for lead content, quality and disintegration. The American equivalent is the United
States Pharmacopoeia (USP) number.
Calcium carbonate is more slowly absorbed than other types of
supplements. To be absorbed, it needs to be completely disintegrated. To determine how quickly a tablet
disintegrates, place it in vinegar and, after 30 minutes, most of it should be disintegrated. When taking a
chewable supplement, the chewing action disintegrates the tablet. To maximize the absorption of the calcium,
keep these tips in mind:
1. Take calcium carbonate with food or immediately after eating.
2. Take calcium with plenty of water.
3. Take no more than 500 mg of elemental calcium at one time.
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I have read that some sources of calcium are better
than others because of something called bioavailability. Can you explain this for
me?
Bioavailability refers to whether the calcium that is found in the food
is available to the body. A major factor is how well it can be absorbed. For example, there are some
vegetables that contain calcium, but they also contain oxalates that bind with the calcium and therefore make
it unavailable for absorption. Such vegetables are spinach, rhubarb and beet greens. Although these are
nutritious foods, they cannot be considered good sources of calcium. Almonds are often cited as a good source
of calcium, but the skins contain oxalates, so the calcium in the whole nut is not very available to the
body.
Three factors are important in determining how much calcium we obtain
from foods. We need to have enough vitamin D to promote absorption. The second factor is how much calcium is
in the serving of food, and the third, whether the calcium is bioavailable. Dairy products such as milk,
yogurt and cheese are less well absorbed (30%) than calcium-rich vegetables (50%), but have a much higher
calcium content per serving. A cup of milk has about 300 mgs of calcium, whereas a cup of cooked broccoli has
about 65 mgs. The calcium from fortified soy beverage is similar in amount but is absorbed at the rate of 70
90% of milk. If you take both calcium content and bioavailability into account, dairy products remain a
good source.
High-fibre foods such as cereals and legumes contain phytates that hinder
absorption by binding with calcium. As long as you are consuming sufficient calcium, this should not be a
problem.
Another aspect of bioavailability has to do with retaining the calcium
you have ingested and absorbed. There can be food components that interfere with how well one can hold on
to the calcium. Excess salt (sodium chloride) and caffeine both cause more calcium to be lost in urine, thus
reducing the overall bioavailability. Adding milk to coffee and cutting back on salt are two ways to prevent
this.
Bioavailability is also a concern if you are relying on calcium
supplementation to get the recommended daily intake. Calcium carbonate and calcium citrate are the most
widely available calcium supplements. Calcium carbonate is not as easily absorbed (on an empty stomach) as
calcium citrate. One can improve absorption of the carbonate form by taking it with a meal. However, both are
effective and the deciding factor in choosing between these two forms is one of personal
preference.
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Why is physical activity so important in managing
osteoporosis?
Physical activity helps to reduce the risk of falls and fractures and to
prevent further bone loss. Physical activity to prevent osteoporosis includes both weight-bearing and
strength-training exercise. Weight-bearing is any exercise where the entire weight of the body is supported
by the legs, such as walking, line dancing, low-impact aerobics or racquet sports. Exercise programs for
people at risk for or with osteoporosis should be aimed at increasing strength, coordination, balance and
flexibility.
For those who are beginning physical activity, seeking advice from a
physiotherapist or fitness instructor can be useful. If you are planning to attend an exercise class, make
sure you ask whether the instructor has training in leading exercise for people with osteoporosis, and knows
what is safe. For people who have recently fractured, a physiotherapist can help by developing and
supervising a rehabilitation exercise plan. (For more information and general guidelines for physical
activity, click here )
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What should I know before I start my exercise
program?
Check with your physician before starting an osteoporosis exercise
program.
Don't do exercises that cause pain.
Stretch before and after exercise.
Choose a facility, leader or trainer who knows the exercise restrictions associated with osteoporosis.
Choose an activity or program that is enjoyable.
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Is the ultrasound test that measures bone density
in the heel bone an acceptable screening tool for osteoporosis?
With osteoporosis still a major and growing health concern for Canadians,
new methods of assessment are always an important area of interest. Recent technology has developed an
alternative technique- quantitative ultrasound (QUS) that measures bone mineral density (BMD) in the heel
and other bones. Several companies in Canada are offering this service privately, outside the
provincial medicare system, for payment by the patient or a sponsor, such as a pharmacy. Osteoporosis
Canada recognizes QUS as a useful tool, especially in areas where dual x-ray absorptiometry (DXA) in not
available: it is inexpensive, portable, easy to use and does not involve ionizing radiation (e.g.
x-rays). But questions remain about how widespread a role it should play in assessing BMD.
The scientific community has raised concerns about the technological
diversity, standards and instrument precision regarding these devices. Quality assurance is another
issue: as yet, no formal training or accreditation process for commercial operators exists. Further,
heel ultrasound detects fewer cases of osteoporosis than DXA and experts arent sure how to deal with the
discrepancy between results from the two tests. Many people who undergo ultrasound testing require
additional DXA test later, leading to more expense and inconvenience. At this time, DXA remains the
diagnostic gold standard for identifying individuals with osteoporosis. Moreover, QUS is not
sufficiently sensitive to changes in bone structure to be used to monitor ongoing therapy for the
disease.
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