Osteoporosis is a common disease in Australia, with 1.2 million people estimated to have the disease. However, it is hard to put a figure on this because many people are simply unaware that they have low calcium density in their bones.
Many remain undiagnosed until they start breaking brittle bones. It is suspected that there are a further 6.3 million Australians currently with low bone density on top of the 1.2 million known sufferers. In total, it affects one in four Australians, especially older Australians.
The underlying mechanism in all cases of osteoporosis is an imbalance between bone resorption and bone formation. In normal bone, remodelling occurs constantly. In fact, up to 10 per cent of all bone mass may be undergoing remodelling at any point in time.
Osteoporosis occurs when this remodelling is incomplete. The three main mechanisms by which osteoporosis develops are: an inadequate peak bone mass, where the skeleton has suffered insufficient calcium when young; excessive bone resorption; and inadequate formation of new bone during remodelling.
Several factors impact on this process including diet, exercise and hormonal issues. Calcium metabolism plays the most significant role in bone turnover, and deficiency of calcium and vitamin D leads to impaired bone deposition. That is why a good, healthy diet including dairy products is essential, and that is why I say drink more milk and eat more cheese and yoghurt.
Hormonal factors also strongly determine the rate of bone resorption. In women, a lack of oestrogen, perhaps as a result of menopause, increases bone resorption as well as decreasing the deposition of new bone that normally takes place in weight-bearing bones. In men, the male hormone testosterone helps maintain strong bones, so low testosterone levels can increase the risk of developing osteoporosis and breaking a bone. Men tend to lose testosterone as they age, and certain medications can affect testosterone levels.
Almost a quarter of all people with osteoporosis are men. In both men and women, hormonal replacement can help prevent or treat osteoporosis. The other vital part of the answer is exercise. Load-bearing exercise like weightlifting is essential.
We can take simple steps to help maintain our bone health at any age. As I said, calcium, vitamin D and exercise are all important for maintaining strong bones. Almost 99 per cent of the body’s calcium is found in our bones.
It combines with other minerals to form hard crystals that give our bones strength and structure. Our most common source of vitamin D is sunlight. This is produced when our skin is exposed to ultraviolet B from the sun. It is pretty prevalent in Australia. We need to take osteoporosis seriously.