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The Importance of Calcium

By Shaun Wadham, Level One Triathlon Coach, Registered Fitness Leader

Taking in calcium via a balanced diet is like saving for the future. If you get on top of it early, your later years will be a lot easier. Put it on the back burner though and you may not have enough calcium savings to meet your body’s spending demands.

The major role of calcium in the body is to develop and continually repair skeletal bone. A certain level must also be present in the blood for the nerves and muscles to function properly. If calcium is not present in the blood the body will withdraw some of the calcium from the bones. If insufficient calcium is absorbed via your diet it is easy for the loss of calcium from the bones to be greater than the intake. The result is a slow but
steady loss of bone calcium. After a number of years the bones become less dense, lose some of their strength and the condition known as osteoporosis occurs. Stress fractures in athletes have also been linked with a low intake of calcium.

Special Problems for Women

Loss of calcium occurs with age in both men and women but women suffer about twice the calcium loss of men. Around menopause, changes in female hormones accelerate the loss of calcium from the bones. The denser the bones are to start with, the less is the likely hood of enough calcium being lost to cause osteoporosis. It is therefore important for women to have built up sufficient calcium in the skeleton over the previous 20-30 years prior to menopause.

Women who are extremely thin or exercise excessively risk having their body fat drop so low that they stop menstruating. This leads to hormonal changes, which in turn leads to the withdrawal of calcium from their bones, which normally doesn’t occur until menopause. This may lead to the early onset of osteoporosis.

Daily Requirements and Calcium Content of Food

Recommended calcium intake for adult males and females is 800mg daily with greater daily calcium requirements of between 1000mg-1300mg during periods of growth, pregnancy and breast-feeding.

Following is a table containing a selection of foods and their calcium content.

Food Calcium
Milk (including skim) 1 cup (250ml) 290
Shape milk (calcium added) 400
Low fat yogurt-200gm tub 350
Cheese-reduced fat-20gm slice 160
Ice cream (2 scoops)-100gm 140
Soy milk (not calcium fortified)-250ml 55
Soy milk (calcium fortified)-250ml 290
Tofu (firm) 130
Salmon (with bones)-100gm 300
Sardines (oil drained)-100gm 350
Almonds (handful)-60gm 150
Orange-1 medium 50
Spinach (cooked)-1 cup-145gm 150
Bread (1 slice)-30gm 20

Factors Affecting Calcium Absorption

Vitamin D and phosphorus, which are easily obtained via a balanced diet, are essential for calcium absorption. Weight bearing exercise is also vital for calcium to be absorbed into the bones.

Excessive protein in the diet leads to a reduction in calcium absorption. A well balanced diet should contain enough protein but not excessive quantities.

A high salt intake, as well as caffeine, nicotine and alcohol consumption also reduces calcium absorption.