There are many ways you can help protect your bones from osteoporosis. In childhood, new bone is added faster than old bone is removed so your bones become larger and denser as you grow.
Adolescence is the most important bone-building period. Once you become a teenager and reach your full height, your bones become more dense.
The thicker your bones are to start with, the less ly they are to eventually become weak and prone to fracture.
Getting plenty of calcium, vitamin D and physical activity are crucial to your bone health. You are never too young or too old to start.
As a child and teenager, calcium, vitamin D and exercise help you build strong bones. As an adult, they help keep your bones strong and prevent osteoporosis.
If you have osteoporosis, they can help slow the rate of bone loss and even increase your bone density.
Women can help protect themselves from osteoporosis by following Canada’s Food Guide to ensure an adequate intake of key nutrients. It is particularly important to get enough calcium and vitamin D.
Calcium and vitamin D
Almost every cell in your body needs calcium. Your heart, nerves, muscles, blood, colon and bones need calcium on a daily basis.
Your bones depend on calcium for strength. About 99 per cent of your body's calcium is stored in your bones. The rest circulates in your blood and takes part in important functions.
If there is not enough calcium circulating in your blood, the body takes the calcium it needs from your bones. The bones act a bank, where you deposit calcium daily and withdraw it as needed.
When calcium is taken from your bones, your bones weaken and become more fragile.
Vitamin D is also vital to the health of your bones:
- it increases your body’s ability to absorb calcium by 30 to 80 per cent, thereby making your bones stronger
- it helps strengthen your muscles
- it has been shown to reduce older adults’ risk of falling by more than 20 per cent
- some initial research has also identified a link between vitamin D deficiency and musculoskeletal pain
Calcium and vitamin D recommendations
Osteoporosis Canada recommends that adults between the ages of 19 and 50, including pregnant or lactating women, get 1,000 mg of calcium and 400 to 1,000 international units (IUs) of vitamin D3 daily. Adults over the age of 50 should get 1,200 mg of calcium and 800 to 2,000 IUs of vitamin D daily.
Food sources of calcium
The best way to get the calcium we need is from food.
Each serving below provides 300 mg of calcium:
|Milk – skim, 1%, 2% or whole milk||1 cup/250 mL|
|Cheese – firm cheeses, such as brick, cheddar, colby, edam, gouda or mozzarella (regular or low-fat)||1½ oz/45 g|
|Cheese – ricotta||½ cup/125 mL|
|Home-made macaroni and cheese||2 cups/500 mL|
|Salmon, canned with bones||½ of a 7.5 oz can|
|Sardines, canned with bones||7 medium fish|
|Frozen yogurt||1 cup/250 mL|
|Blackstrap molasses||2 tablespoons/1 fluid oz|
|Tofu – regular, set with calcium sulfate||1 cup/250 mL|
|Tofu – firm, set with calcium sulfate||½ cup/125 mL|
|Rice beverage, calcium-fortified||1½ cups/375 mL|
|Soy beverage, calcium fortified||1½ cups/375 mL|
|Soybeans, cooked||2 cups/500 mL|
|Bok choi, cooked||1 cup/250 mL|
|Kale, cooked||1½ cups/375 mL|
|Mustard greens, cooked||1½ cups/375 mL|
|Turnip greens, cooked||¾ cups/188 mL|
|Broccoli, cooked||4 cups/1 L|
|Almonds||¾ cup/188 mL|
|Orange juice, calcium-fortified||1 cup/250 mL|
The best source of calcium is milk and calcium-rich foods. Consider supplements if it is impossible to get enough calcium from your diet. Your doctor or a registered dietitian can recommend the amount and type of calcium supplements you need to take.
Sources of vitamin D
Vitamin D occurs naturally in very few foods: cod liver oil, fatty fish, such as salmon, tuna, mackerel or sardines, and egg yolks. Vitamin D is also added to milk and some rice and soy beverages. For adults over 50 years of age, it is almost impossible to get the recommended daily intake of vitamin D through food sources alone.
Sunshine helps your body to produce vitamin D. Ten to 15 minutes exposure on your hands and face without sunscreen every day is recommended. In the fall and winter months, the sun becomes weak in Canada and does not allow us to get as much of the vitamin. For this reason, your doctor may recommend vitamin D supplements.
Be aware that it is possible to get too much vitamin D. How much is too much is the subject of debate: Health Canada advises against taking more than 2,000 IUs a day whereas others say anything under 10,000 IUs is safe.
Women achieve their maximum bone mass in their teenage years. The more bone mass you accumulate before that age, the more ly you are to have healthy, strong bones later in life.
Yet Canada’s Report Card on Physical Activity for Children and Youth for 2008 shows that less than half of children in Canada get the amount of exercise they need each day for healthy growth and development.
And girls tend do less physical activity than boys: only 36 percent of girls are meeting physical activity guidelines.
Examples of weight-bearing activities include:
- climbing stairs
- Tai Chi
- aerobics and step classes
- racquet sports, tennis
- skipping rope
- lifting weights
Low-impact activities, such as cycling, swimming and using an elliptical machine, are great forms of exercise but they are not weight-bearing.
Muscle strengthening activity
Activities that strengthen your muscles also make your bones denser, and improve your posture and balance. Muscle strengthening exercises can be done at home or in a gym by
- using strap-on velcro ankle and wrist weights
- lifting free weights
- using weight machines
- doing exercises that strengthen your core
- doing exercises that use your own body weight to exercise your muscles (such as push-ups, curl-ups, lunges and squats)
Consult an exercise specialist to determine which exercises are most appropriate for you.
To promote the health of our bones and prevent osteoporosis, we can also quit smoking, and limit the amount of caffeine and alcohol we consume.
Smoking can cause women to reach menopause as much as five years earlier, which has a direct effect on bone loss. Smoking can also reduce your body’s ability to absorb calcium. Regardless of your age, quitting smoking is good for your bone health.
Caffeine is a diuretic. This means you go to the bathroom more when you drink coffee, tea or carbonated drinks that contain caffeine. As a result, you lose more calcium in your urine.
Drinking moderate amounts of caffeine is safe, but try to avoid having more than three cups of coffee a day.
We don't fully understand the relationship between alcohol and bones, but we do know that alcohol can have a toxic effect on the liver, and may interfere with calcium absorption. Alcohol is also a diuretic so it increases the amount of calcium lost in the urine. Try to drink no more than one or two alcoholic beverages a day.
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Vitamin D: How much is too much of a good thing? High doses of vitamin D may result in a decrease in bone density
When bare skin is exposed to sunlight, it makes Vitamin D, which is needed by our bodies to absorb calcium and ensure strong, healthy bones.
With bathing suit skin exposure, it only takes about 10-15 minutes of sun exposure during the summer to generate all the vitamin D your body needs for the day.
Unfortunately, for Canadians, exposure to sunlight is diminished during the long winter months. This results in many turning to supplements to get the required vitamin D.
For normal, healthy adults, Health Canada recommends a total daily intake of 600 international units (IU) up to age 70, and 800 IU after age 70.
Other sources, Osteoporosis Canada, suggest adults at risk of osteoporosis, a condition characterized by bone loss, should take 400 — 2,000 IU of Vitamin D.
However, some people may be taking up to 20 times the recommended daily dose to prevent or treat a variety of medical conditions that might be related to having not enough vitamin D. So, what is the correct dose? And, how much is too much?
“Although vitamin D may be involved in regulating many of the body's systems, it is the skeleton that is most clearly affected by vitamin D deficiency,” says Dr. David Hanley, MD, an endocrinologist in the Cumming School of Medicine (CSM), and one of the principal investigators of the study.
“Current Health Canada recommendations were set to prevent the bone diseases caused by vitamin D deficiency for the vast majority of healthy Canadians. But it has been more difficult to clearly establish the optimal dose of vitamin D.
When we designed this study, there remained a question whether there's more benefit in taking a higher dose.”
A three-year study by researchers at the Cumming School of Medicine's McCaig Institute for Bone and Joint Health published in the Journal of the American Medical Association (JAMA), showed there is no benefit in taking high doses of vitamin D.
The study followed 300 volunteers between the ages of 55 and 70 in a double-blind, randomized clinical trial to test the hypothesis that with increasing doses of vitamin D, there would be a dose-related increase in bone density and bone strength.
A third of the study participants received 400 IU of vitamin D per day, a third received 4,000 IU per day, and a third received 10,000 IU per day.
Volunteers had both their bone density and bone strength measured using a new, high-resolution computed tomography (CT) scan of bone at the wrist and ankle, called an XtremeCT, used only for research.
The XtremeCT, located in the McCaig Institute's new Centre for Mobility and Joint Health, is the first of its kind in the world, and allows researchers to look at bone microarchitecture in detail never seen before. Standard dual-X-ray absorptiometry (DXA) bone density was also obtained. Participants received scans at the start of the study and at 6, 12, 24 and 36 months.
To assess vitamin D and calcium levels, researchers also collected fasting blood samples at the beginning of the study and at 3, 6, 12, 18, 24, 30 and 36 months as well as urine collections annually.
Bone mineral density (BMD) is determined by measuring the amount of calcium and other minerals in a defined segment of bone. The lower the bone density, the greater the risk for bone fracture.
Adults slowly lose BMD as they age, and the DXA results showed a modest decrease in BMD over the duration of the study, with no differences detected between the three groups. However, the more sensitive measurement of BMD with high resolution XtremeCT showed significant differences in bone loss among the three dose levels.
Total BMD decreased over the three-year period by 1.4 per cent in the 400 IU group, 2.6 in the 4,000 IU group and 3.6 in the 10,000 IU group.
The conclusion was that, contrary to what was predicted, vitamin D supplementation at doses higher than those recommended by Health Canada or Osteoporosis Canada were not associated with an increase in bone density or bone strength.
Instead, the XtremeCT detected a dose-related decrease in bone density, with the largest decrease occurring in the 10,000 IU per day group. More research is required to determine if high doses may actually compromise bone health.
“We weren't surprised that using DXA we found no difference among the treatment arms, whereas with XtremeCT, the latest in bone imaging technology, we were able to find dose-dependent changes over the three years.
However, we were surprised to find that instead of bone gain with higher doses, the group with the highest dose lost bone the fastest,” says Steve Boyd, a professor in the CSM and one of the principal investigators of the study.
“That amount of bone loss with 10,000 IU daily is not enough to risk a fracture over a three-year period, but our findings suggest that for healthy adults, vitamin D doses at levels recommended by Osteoporosis Canada (400-2000 IU daily) are adequate for bone health.”
A secondary outcome of the study indicated a potential safety concern with taking high levels of vitamin D.
Although there were incidents in all three arms of the study, the investigators found that participants assigned to receive higher doses of daily vitamin D supplementation (4000 IU and 10,000 IU) over the three years were more ly to develop hypercalciuria (elevated levels of calcium in the urine), compared to those receiving a lower daily dose. Hypercalciuria is not uncommon in the general population, but is associated with increased risk of kidney stones and may contribute to impaired kidney function.
Hyperalciuria occurred in 87 participants. Incidence varied significantly between the 400 IU (17%) 4000 IU (22%) and 10,000 IU (31%) study groups. If hypercalciuria was detected in study participants, calcium intake was reduced. After repeat testing, the hypercalciuria usually resolved.
“What we can see in this study is that large doses of vitamin D don't come with a benefit to the skeleton,” says Dr. Emma Billington, MD, one of the authors of the study. “For healthy adults, 400 IU daily is a reasonable dose. Doses of 4,000 IU or higher are not recommended for the majority of individuals.”
Materials provided by University of Calgary. Note: Content may be edited for style and length.