We never really think of our bones as being a living tissue – they're there, out of sight, doing their job, and it's not until we break one that we might begin to worry.
Osteoporosis literally means "porous bones" and is often thought of as a disease of older women but it can affect men and younger women.
Up to 80% of our bone health is influenced by heredity but lifestyle factors play a part. Increasingly, experts believe sedentary lifestyles and fad diets, as well as more smoking and drinking puts younger women at a greater risk of osteoporosis later in life because they interrupt the crucial bone-building pattern. This can mean more chance of hundreds of thousands of spinal bones, hip and wrist fractures that happen every year because of osteoporosis.
Bone tissue is constantly changing as old bone is destroyed and is replaced by new cells. It is made up of a hard outer shell made of tough elastic fibers and an inner honeycomb structure. In healthy bone the honeycomb is dense, with few spaces in the mesh but in osteoporotic bone there are more holes, which makes it weaker and more prone to breaking.
Calcium, phosphorous and amino acids are absorbed from the blood stream and built into bone under the influence of sex hormones – oestrogen and testosterone.
For most people bone mass peaks in their thirties and from the age of about 45 it typically declines slowly as slightly more bone is lost than is made. In women, menopause sees a reduction of oestrogen, which is why there is a sharp loss of bone mass in women over fifty and an increase in osteoporosis and bone fractures.
The advice from the National Osteoporosis Society (www.nos.org) for preserving bone health is that men and women of all ages should aim to:
Get enough Vitamin D. It's essential for the absorption of calcium and this comes from sunlight and some vegetables – see the Web site for more details. Talk to your physician about a supplement if you think you need one.
Regular exercise is essential for bone strength. Weight bearing exercise like walking, dancing and aerobics will also reduce high blood pressure, and positively affect mental health. This will also improve your balance and posture which will protect you from falls.
Stop smoking. Work with your healthcare provider to find the right program for you.
Keep alcohol consumption within safe limits. This means less than 3 drinks a day. Have a good calcium intake. The recommended daily intake is 800mg calcium – half a pint (250ml) cow's milk or a 150g yogurt gives you 300mg. Low fat options have the same amount of calcium as full fat. Non-dairy sources of calcium include nuts and pulses, dark green leafy vegetables such as broccoli and spinach, mackerel, salmon and tofu.
Take supplements. Discuss taking a supplement with your physician if you are concerned or have a family history of osteoporosis.
Osteoporosis detection is done by a DXA (dual energy x-ray absorbtiometry) scan. Done in the hospital, this measures the bone density and the results can predict the likelihood of future fractures. It's painless, takes about 15-30 minutes and the patient stays fully dressed.
Treatment for osteoporosis is primarily by drugs that slow the rate of bone decay so that there is a net increase in bone strength over time. Drugs such as bisphosphonates do this. They have mainly digestive side effects – diarrhoea, constipation, indigestion etc.
For women who can't take bisphosphonates, strontium helps to increase bone formation as well as decreasing its breakdown but has been linked to an increased risk of blood clots.
Evista can prevent and treat osteoporosis in post-menopausal women by stimulating bone growth in the same way that natural oestrogen does.
There are other causes of osteoporosis as well as heredity and lifestyle. People who have taken steroid medications for a lengthy period, who've had certain hormonal imbalances such as an over active thyroid or parathyroid gland or a prolonged immobilisation should all discuss their risk of osteoporosis with their GP or see www.nos.org for more information.
October 20th is World Osteoporosis Day, which aims to raise awareness of the disease and encourage people of all ages to invest in taking care of their bones for life.