During adolescence, sufficient amounts of calcium help strengthen and consolidate bones, so that individuals attain optimum bone mass, in accordance with their predetermined genetic program. A two-year study conducted by V. Matkovic on the effects of calcium supplements on children showed that by doubling the calcium intake of adolescents to 1600 milligrams per day bone mass can be significantly increased.
Similar results were obtained by C.C. Johnston on monozygotic (identical) twins aged 6 to 14. One twin in each pair received 1600 milligrams of calcium, as opposed to about 900 milligrams without supplements for the other twin. After three years the bone mass of twins who received the supplement was 8.5% higher than those who had not been given supplements. This study proves the determining role calcium plays in building bone mass, and at the same time eliminates the genetic factor.
Inversely, if calcium intake is insufficient during adolescence, growth proceeds normally but bones become much more fragile. If the deficit is not at least partially corrected before the age of 30 to 35, the risk of developing osteoporosis becomes much greater.
Another study (Kelly) confirmed the direct relation between bone density and calcium intake in adult male twins. And a number of other studies on pre-menopausal women have demonstrated the positive effects of calcium supplements on bone mass. According to one such study (Baran) ingesting large amounts of calcium (1500 milligrams per day instead of the usual 900 milligrams) prevents vertebral bone loss in women between the ages of 30 and 42.
Most people get most of their calcium from dairy products, which provide between 60% and 80% of the calcium obtained from food sources. Dairy products have the advantage of containing large amounts of calcium in a form that is especially easy to assimilate (the average coefficient of absorption is between 25% and 40 %, depending on the testing methods). In addition, the variety of dairy products available on the market helps people meet their daily requirements with ease, even if they are on a diet.
To obtain 1200 milligrams of calcium you would need to:
– drink 1 quart (litre) of milk per day;
– drink a pint of milk and eat 2 servings of yogurt and 1 portion (1 ounce or 30 grams) of cheese;
– drink ½ pint of milk and eat 2 servings of yogurt and 2 portions (2 ounces or 60 grams) of cheese;
– eat 3 servings of yogurt plus 1 dairy snack and 2 portions of cheese.
Many people, especially younger women, go on weight-loss diets. It is possible to maintain adequate calcium intake even while you’re dieting if you eat a sufficient amount of dairy products. In many diets low-fat dairy products, which are rich in protein, low in fat and contain little or no sugar, are recommended. The large array of available products (skim milk, low-fat cheese and yogurt, etc.) helps add diversity to what might otherwise be a rather boring diet. Fortunately, low- fat dairy products retain all their nutritional value, except for some modification of liposoluble vitamins (Vitamins A and D).
However, it has been shown that weight-loss diets can have a negative impact on bone mass.
A vegetarian diet, especially one which excludes all animal products, including milk, cheese and eggs can easily result in a calcium deficiency. Even though some vegetarian foods contain fairly large amounts of calcium, they are generally not able to meet an average adult’s daily requirements.
For example, to obtain 300 milligrams of calcium a vegetarian would have to eat 2.2 pounds (1 kilogram) of oranges, 2 pounds (850 grams) of cabbage, 10 ounces (300 grams) of broccoli, 5 ounces (150 grams) of soybean flour or 5 to 10 ounces (150 to 300 grams) of tofu. Add to that the fact that calcium from vegetal sources is more difficult for the body to assimilate, because of the presence of fibres and oxalic and phytic acids. A vegetarian diet that includes dairy products and milk is much less unbalanced, although there is still a danger of absorbing too much fibre.
It is possible to reduce your risk of developing osteoporosis at almost any age, by taking a few simple precautionary measures. Maintaining a balanced diet that is rich in calcium, and engaging in regular physical activity from adolescence through your adult life constitute the best prevention against the disease.
Drink milk during meals and snacks, and include at least one dairy product (cheese, yogurt, cream, milk-based preparations, etc.) with each meal.
– Vary the kinds of dairy products you use as much as possible.
– Add milk or other dairy products to cooked or prepared dishes whenever possible: a slice of cheese in sandwiches, milk or cream in tea or coffee, etc.
– Drink hot or cold dairy beverages: chocolate milk, mint or strawberry-flavoured milk, and add a little milk to soups, scrambled eggs, etc.
– When you eat junk food (not too often we hope!) drink milk shakes and get your burgers topped with cheese.
– You can cook delicious meals that require melted cheese: vegetables or fish ‘au gratin,’ souffles, pasta, bechamel sauce, and so on.
– Add grated cheese to salads, omelets or soup.
– Get children into the habit of eating a slice of toast with cheese for a snack instead of chocolate, jam, peanut butter, etc.
– Individually packaged dairy products make it easy to carry a couple of dairy snacks wherever you go.
Also remember that prudent but regular exposure to direct sunlight, and at least a moderate amount of physical exercise, are both essential for providing bones with the minerals they need.