Are you getting enough calcium in your diet? Don't be so sure.

Calcium is essential to prevent osteoporosis, a bone disease that affects more than 1.4 million Canadians. Yet according to a recent study published in the Journal of Public Policy and Marketing from researchers at the University of Wisconsin-Milwaukee, food labels that list calcium as a percentage of daily intake often confuse consumers and can lead to under-consumption of the mineral.

Fractures resulting from osteoporosis often occur in the wrist, hip and spine - injuries that can be difficult to heal and very painful, leading to a loss of mobility and independence in older adults.

People can end up consuming less calcium than they need because they aren't able to translate the daily percentage into the amount of calcium a product actually contains, the study says.

Compounding the issue is the fact that the body can only absorb a certain amount of calcium at a time, so eating foods with large amounts of the mineral doesn't necessarily mean your body is able to use it all.

Risk factors

Osteoporosis develops over many years and is characterized by loss of bone mass, resulting in fragile bones that are prone to fractures. It is often known as the "silent thief," because bones can weaken over time without any visible symptoms or warning — until a fracture occurs.

And the problem isn't just that the bones break. The fractures usually occur in the wrist, hip and spine — injuries that can be difficult to heal and very painful, leading to a loss of mobility and independence in older adults.

According to Osteoporosis Canada, one in four women will develop osteoporosis, while one in eight men will get the disease.

Risk factors include:

• A family history of osteoporosis
• Smoking
• Consumption of excess amounts of alcohol
• Consumption of excess amounts or caffeine (more than 4 servings of coffee, cola, or energy drinks per day)
• Age (65 years or older)
• A low calcium intake
• A sedentary lifestyle
• Disorders that make it difficult to absorb calcium and vitamin D
• Early menopause (before the age of 45)

While these factors can provide a general idea of your risk of developing the disease, the most accurate way to assess your risk is through a diagnostic bone mineral density test. The test is a quick and painless procedure that uses x-rays to scan the spine and hip(s) to determine the density of your bones, and can therefore determine your risk of developing osteoporosis.

Osteoporosis and calcium

Calcium is critical for proper bone growth and development, and an adequate intake of the mineral throughout your life may lower your risk of developing osteoporosis. Women have been the object of osteoporosis campaigns for many years, but researchers point out that men are also at risk.

The most accurate way to assess your risk of osteoporosis is through a diagnostic bone mineral density test, a quick and painless procedure that uses x-rays to scan the spine and hip(s) to determine the density of your bones.

During childhood and adolescence our bones act like sponges, absorbing as much calcium as they can get from regular dietary material and supplements to form a dense, strong skeleton.

At about the age of 20, bone mass peaks. From that point on, as part of the natural aging process, bones begin to lose calcium and they break down faster than they can be regenerated. But generally speaking, bones that are rich in calcium will take longer to degenerate than bones that are lacking calcium, so it's important to build bone mass early in life.

Yet according to Statistics Canada, more than 30 per cent of children and 65 per cent of adults do not consume the recommended daily servings of milk products – the main source of calcium in the diet.

How much calcium do you need?

Calcium intake and osteoporosis go hand-in-hand. While ensuring your diet includes adequate calcium may not be able to prevent osteoporosis altogether, it may be the single most important thing you can do to lower your risk.

Health Canada suggests that adults under the age of 50 get 1,000 milligrams of calcium per day. It recommends adults over the age of 50 get 1,200 mg of calcium each day.

And while your dietary patterns early in life are important, it is never too late to add calcium-rich foods. The following chart gives an idea of how foods stack up in terms of calcium content.

Nutritional information obtained from Canadian Nutrient File, 2007

Food	Amount of calcium
Cheese (cheddar) (50 g)	452 mg
Yogurt (1%) (3/4 cup)	320mg
Calcium fortified soy beverage (1 cup)	319 mg
1% Milk (1 cup)	307 mg
Tofu, firm (3/4 cup)	234 mg
Canned salmon, with bones (1/2 cup)	208 mg
Calcium fortified orange juice (1/2 cup)	185mg
Almonds (1/4 cup)	89 mg
Broccoli, raw (1/2 cup)	22 mg

When reading nutrition labels, calcium is often listed as a percentage of daily value (%DV). This number is based on the current recommendation of 1000 milligrams per day. Foods that contain 15 per cent or more of the daily value of calcium are considered a good source, while foods that contain 25 per cent or more of the daily value of calcium are considered an excellent source.

People who do not receive enough calcium through their diet can take a supplement.

When choosing a calcium supplement, note the amount of elemental calcium it contains; your body can only absorb 500 mg at a time. Calcium supplements should always be taken with food, and plenty of water.

A word on vitamin D

Vitamin D also plays a critical role in the prevention of osteoporosis, since it is responsible for the proper absorption of calcium.

Vitamin D is also known as the "sunshine vitamin" because it is manufactured in the skin during sun exposure. As a result, people in northern latitudes such as Canada and people who avoid the sun are at risk of a deficiency.

Based on recent study findings that linked vitamin D to a decreased risk of certain cancers, the Canadian Cancer Society now recommends Canadian adults receive 1,000 international units (IU) of the vitamin per day, through a supplement during the fall and winter. Those with elevated risk of certain cancers are encouraged to consume that much year-round.

Vitamin D can also be obtained from milk, fortified milk alternatives, fish, liver and egg yolk.

Drug treatments

There are a number of treatments available to people living with osteoporosis that aim to reduce the incidence of fractures.

Some of these treatments include drugs that bind to the surface of the bone to reduce the rate of bone loss, while others work to increase the rate of bone formation. Other treatments, including hormone replacement therapy, supplement hormones that are lost during the natural aging process and aim to prevent the bone loss that is associated with aging.

Regardless of the type of drug treatment that is chosen, it is important to continue eating a diet rich in calcium and vitamin D to promote the growth of bones that are as strong as possible.

Reduce your risk

Reducing your intake of caffeine and exposure to tobacco can also help reduce the risk of osteoporosis. Regular exercise and weight-bearing activities are also recommended as a way to maintain strong bones.

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