Of the body's calcium, 99% is stored in your skeleton where it is critical in bone formation. The remaining 1% if found in various body membranes, soft tissues and body fluids. Besides its role in bone-formation, calcium is also involved in blood clotting, nerve transmission, muscle contraction and enzyme activity.

Osteoporosis is the term generally used to describe drastic loss of calcium from bones which is often seen in post-menopausal women. The condition leads to lower bone density and to brittle bones. The term osteopenia better describes the condition found in some athletes. With this, there is a reduced bone mass which may be a result of inadequate bone formation during growth or loss of bone mass due to low oestrogen levels.

Who Is At Risk ?

Some women, particularly endurance athletes, ballet dancers or gymnasts, may experience delayed menarche or other menstrual irregularities (called sports amenorrhoea). These athletes usually have a low percentage of body fat, exercise rigorously and have low oestrogen levels. Having low oestrogen levels will accelerate bone loss and, as a result, lead to a decrease in bone density.

Other risk categories include athletes with eating disorders, veteran athletes and post-menopausal women.

How Do I Know IF I Have Osteopenia ?

Often than being susceptible to bone fractures, the only way to find out whether or not you have osteopenia is by having a bone ultrasound.

How Can I Protect Myself ?

Today we know that the combination of weight-bearing exercises (such as walking or jogging) and sufficient calcium in your diet, as well as adequate oestrogen levels help to protect you from osteopenia. If you belong to any of the above groups, you will need 1,000-1,500 mg of calcium daily. This means drinking plenty of low-fat milk, and eating plenty of low-fat cheese, yoghurt and other dairy products.

Best Sources of Calcium

The richest, and most easily absorbed source of dietary calcium are dairy products. Canned fish with bones, fortified soy beverages, nuts, seeds and leafy green vegetables are also good calcium sources. For the greatest overall benefit, keep these two points in mind:

- Diets too high in salt, protein, caffeine, phosphorus or fiber will inhibit your body's ability to absorb calcium from your food.

- Full-cream dairy products are also high in fats. Make sure you use skimmed, low-fat or reduced-fat dairy products.

If you eat a well-balanced diet, you should receive enough calcium.