Responding to the Reader
Osteoporosis
What can we do to prevent it?
Story by Laura Ly/Illustration by Darcy Muenchrath
About this feature
Alberta Innovates - Health Solutions frequently receives letters requesting information about Heritage research or about various medical conditions. "Responding to the reader" is a Research News feature intended to provide up-to-date information related to readers' questions, with the help of experts in the Alberta research community. Alberta Innovates - Health Solutions cannot provide medical advice, however; please consult your family physician about your specific health concerns.
Osteoporosis, a disease characterized by bone deterioration, is known as the "Silent Thief" because bone loss occurs without symptoms. Luckily, factors such as nutrition and exercise can help prevent bone loss before osteoporosis occurs. Dr. David Hanley, director of the Calgary Centre of the Canadian Multicentre Osteoporosis Study, and Dr. Steven Boyd, a researcher in the Bone Imaging Laboratory at the University of Calgary, provide some insights on how to prevent bone loss as we age.
Although osteoporosis is most commonly diagnosed in the elderly—in post-menopausal women, for example—it can occur at any age. "Your bones deteriorate with age; that is a normal process. It's when bones deteriorate too much that you have osteoporosis," explains Dr. Boyd. People with osteoporosis are at increased risk of bone fractures, especially in the wrists, spine, and hips.
Calcium, which is one of the building blocks of bones, is essential to the development and maintenance of your skeleton. A high calcium intake is critical for adolescent children while their bones are growing. Adults' bones stop growing, but calcium is still necessary for maintaining the existing bone mass.
"Blood calcium is necessary for many functions, such as nerve transmission, muscle function, and blood coagulation. We have a hormone system that regulates blood calcium, and bones are used as our calcium bank. If your diet is calcium-deficient, your body will sacrifice the calcium in your bones to maintain the blood calcium," explains Dr. Hanley. Regular withdrawals from the body's calcium bank can lead to osteoporosis.
Osteoporosis Canada suggests that adults between the ages of 19 and 50 receive at least 1000 milligrams of calcium a day. Adults over the age of 50 should receive 1500 milligrams. Dairy products are an easy way to get calcium. "A typical Canadian diet without dairy products would give you about 400 milligrams of calcium a day. A cup of milk, a cup of yogurt, or a standard serving of hard cheese would give you 300 milligrams alone, so it doesn't take very much to reach an optimum level of daily calcium," says Dr. Hanley. Other sources of calcium include calcium supplements, canned fish with bones, and almonds. Excess calcium is excreted through the urine and feces.
Vitamin D, which helps facilitate calcium absorption, is also an important part of a diet to prevent osteoporosis. Only a few foods—such as milk, fish, liver, and egg yolk—are sources of this vitamin, but the body naturally produces vitamin D when exposed to the sun's ultraviolet rays. The Canada Food Guide recommends vitamin D supplements for people who live in locations that receive little sun, especially during the winter months.
Exercise is also important for osteoporosis prevention. "Calcium is the building block of bones, but exercise is what stimulates bone-building," says Dr. Boyd. In particular, weight-bearing exercise—exercise that works your bones against gravity—is most effective at building and strengthening bone. "Your bones need a mechanical stimulus in order to be maintained. Weight-bearing exercises load the bones and provide that stimulus to prevent bone loss from occurring." Activities such as walking and running are examples of weight-bearing exercise; exercises that are not weight bearing include swimming. Studies show that people who do intensive weight-bearing exercise, like boxers or tennis players, have a higher bone-mineral content than people who swim. "However," he adds, "any kind of activity will help your bones."
Different types of exercise stimulate different bones in the body. "For example, walking is weight-bearing exercise for your lower legs. You're stimulating your forearms while playing tennis. The benefits are specific to where the weight-bearing occurs," explains Dr. Boyd.
In addition, moderating or avoiding cigarettes, alcohol, and caffeine—substances that accelerate bone loss—will also help prevent osteoporosis. These strategies for prevention have been shown to slow the rate of bone deterioration and diminish the effects of osteoporosis after onset. Regardless of age and the stage of bone loss, it is never too late to reap the benefits of exercise and nutrition—your bones will be stronger for it.