By William Reville
It is very important to have strong bones. Unfortunately from about age 30 onwards everyone starts to lose substance from their bones and this can eventually develop into osteoporosis, when the bones become fragile and more likely to break. The disease is common in elderly people. Women are four times more likely than men to develop the condition and about 30 per cent of women over 50 develop osteoporosis. There is no cure but the disease can be treated and can also be prevented by taking simple steps.
If osteoporosis is not prevented or treated it can progress painlessly until a bone breaks, typically in the hip, spine or wrist with hip fractures usually requiring major surgery. On average, 24 per cent of hip fracture patients aged 50 and over die in the year following the fracture.
Factors that increase the likelihood of developing osteoporosis include being a female, having a thin frame, advanced age, family history, being post-menopausal, abnormal absence of menstrual periods, anorexia nervosa or bulimia, low-calcium diet, certain medications such as anti-convulsants or corticosteroids, inactive lifestyle, low male testosterone levels, excessive ******* intake, smoking and being Caucasian or Asian.
Our bones act like scaffolding, providing structural support for muscles, protecting vital organs and storing the calcium which is essential for bone density and strength. Bone is a complex tissue and undergoes constant turnover involving the build-up and breakdown of tissue. Bones are constantly changing, they heal after injury and are affected by diet and exercise.
Until the age of about 30 you build bone faster than you break it down, but during the later ageing process your bones break down faster than new bone is formed.
The critical years for building bone are from pre-adolescence to about age 30. The more bone you have "in the bank" at that stage the less likely you are to develop osteoporosis later. Women are more likely than men to develop osteoporosis because, on average, their bones are smaller and less dense than mens' bones. Also, bone loss accelerates after the menopause when the ovaries stop producing the female sex hormone that protects against bone loss.
To determine if you have osteoporosis, or may be at risk of developing the condition, your family doctor will ask questions about your lifestyle and medical history, e.g. has anyone in your family suffered from osteoporosis or fractured bones. Based on this assessment you may be referred for a bone mass measurement. This painless, non-invasive and safe test is the only way to tell for sure if you have osteoporosis.
The good news is that osteoporosis is largely preventable by taking four steps. No single step alone prevents the disease. The steps are: (a) eat a balanced diet rich in calcium and vitamin D; (b) do weight-bearing exercises; (c) adopt a healthy lifestyle with no smoking or excessive use of *******; (d) test bone density and take special medications when appropriate.
Inadequate calcium intake contributes to the development of osteoporosis, and many girls and women consume less calcium than recommended to maintain healthy bones. Depending on age, an appropriate calcium intake is between 1,000 and 1,300 mg a day. You can increase dietary calcium by eating calcium-rich foods such as milk, cheese, broccoli, etc.
Vitamin D is necessary for the body to absorb calcium from food in the intestine. Apart from building bone, your body needs calcium for other purposes such as allowing the heart, muscles and nerves to function properly. If you are not absorbing enough calcium from food your body takes the calcium it needs from your bones. Vitamin D comes from two sources: it is made in the skin when exposed to sunlight, and it is obtained from the diet. As we age the ability to make vitamin D in the skin decreases. It is recommended that we take 400 to 800 international units of vitamin D daily. Major food sources of vitamin D are fortified dairy products, egg yolks, saltwater fish and liver.
Unlike mechanical machines that wear out with use, our bodies get stronger the more (within reason) they are used. Bones become stronger and denser when demands are made on them and conversely, lack of exercise particularly as you get old may contribute to lower bone density.
Two types of exercise are important for building bone density - weight-bearing and resistance exercises.
In weight-bearing exercise your muscles and bones work against gravity, e.g. jogging, walking, climbing stairs and football.
Resistance exercises are weight-lifting exercises. Many daily activities and most sports involve both types of exercise.
Hormone replacement therapy (HRT) has proved useful for the prevention and management of osteoporosis in post-menopausal women. Some women experience side-effects and the HRT approach should be carefully discussed with a medical specialist.
William Reville is a Senior Lecturer in Bio-chemistry and Director of Microscopy at UCC.