There are four main types of osteoporosis: juvenile, idiopathic, postmenopausal and senile. This entry deals with the cause and prevention of postmenopausal only.

Postmenopausal Osteoporosis is a condition that mainly affects older women and is characterized by a decrease in bone mass.

The Cause

There are two main types of cells in bones, called osteoclasts and osteoblasts, and these destroy and rebuild the bones in microscopic quantities. The osteoclasts dissolve cavities in the bones, and the osteoblasts repair the cavity, filling it with new bone. In postmenopausal osteoporosis, more osteoclasts than usual are working, each creating a bigger cavity than before. The osteoblasts still appear for repairs, but this is no longer sufficient to completely fill the cavities. As the bone mass falls, the bones become honeycombed inside, and are much more likely to break after a fall.

If there is not enough calcium in the blood it is withdrawn from the bones, only being replaced when the level in the blood is stable. Any excess is treated as waste. The more calcium is withdrawn from the bones, the weaker they become. The weaker they become, the less space there is to store calcium. A vicious circle has begun.

In women, the hormone oestrogen also contributes to bone growth. During the menopause, the amount produced begins to fall until eventually almost none is produced as the menopause ends¹. Other factors can affect the speed of bone loss, but the loss of oestrogen is the main cause.

Prevention

The best women can do for their bones to protect them from the loss of oestrogen is to make sure that they reach peak bone mass, thus giving them the strongest chance to survive.

For under 25s

• Take plenty of exercise and the equivalent of half a litre of milk a day.

• Eat a balanced diet, including protein, fresh fruit and vegetables, dairy products and roughage.

• Go out in the sunlight with bare arms and legs as much as possible. Twenty minutes per day gains the appropriate amount of vitamin D in the summer.

• Don't smoke and drink as little alcohol as you can.

25 to 35

• Keep your calcium intake up to 1,000mg per day².

• Don't smoke or drink.

• Make sure you do weight-bearing exercise at least three times a week for 30 minutes. Walking is ideal, swinging your arms as you go.

• Keep going out in the sunlight, 20 minutes per day on bare arms and legs.

• Try to stay the the best weight for your height.

From 35 until the Menopause

• Keep your calcium intake up to 1,000mg per day.

• Don't smoke. This doubles your chance of getting osteoporosis.

• Make sure to do weight-bearing exercise at least three times a week for 30 minutes. Walking is ideal, swinging your arms as you go. Jogging can now do damage to bones and muscles, so give up.

• Keep going out in the sunlight, 20 minutes per day on bare arms and legs.

• Try to stay the best weight for your height. Some oestrogen is stored in fat; being underweight lowers your level.

• Don't eat too much meat. The skeleton no longer needs so much protein for growth. Too much, and calcium will not be stored.

• From the age of 40, go to the doctor if you suffer from back pain and ask to be checked for fractured vertebrae.

• Also be measured once a year. Losing height is an early sign of osteoporosis.

From the Menopause until 60-65

• Ask your doctor about Hormone Replacement Therapy.

• Keep your calcium intake up to 1,000mg per day if you are on HRT. 1,500mg if not.

• Watch for signs of loose teeth or gum disease. Visit the dentist twice a year.

• Change to decaffeinated coffee, as caffeine leeches calcium from your bones.

• Have a glass of milk before bed. Calcium is lost overnight after the menopause.

• Be very careful when lifting. Keep your back straight, and don't lift objects from too far away. Don't lift anything with your spine twisted, and concentrate on what you are doing.

• Be measured twice a year.

After 60/65

• Keep your calcium intake up to 1,200mg per day.

• If you are high-risk for ostoeporosis, avoid vigorous activity such as running up and down stairs.

• Take a Vitamin D supplement.

• Keep up exercise. Brisk walking is still the best type you can do.

• Try to eat well. Being undernourished puts you at more risk of falling and being thin gives your bones less of a cushion to absorb the shock.

• Be measured twice a year.