Calcium: The Bone Builder

Adolescence provides a window of opportunity for avoiding osteoporosis later in life. The disease silently depletes the bones of calcium, typically over the course of decades. Eventually the bones lose their density and weaken; half of all fractures in women over age fifty are due to osteoporosis.

During the teenage years, the growing bones absorb more calcium from the blood than at any other time of life. By early adulthood, our bones stop accepting deposits. Not long after that, the gradual loss of calcium begins. In women, it accelerates following menopause, when the ovaries cease producing estrogen. “Girls who don’t consume enough calcium as adolescents start out at a deficit, with a lower bone mass,” Mary Story explains. In a clinical study sponsored by the National Institute of Child Health and Human Development, one group of teenage girls received daily supplements containing an extra five hundred milligrams of calcium; the other group’s calcium came strictly from food with no supplement. The girls who were given supplements saw their bone density improve by 14 percent. Each 5 percent increase in bone mass reduces the risk of suffering a bone fracture by a remarkable 40 percent.

Milk and milk products provide three-fourths of the calcium in the American diet. Other foods contain calcium too, like broccoli and collard greens. However, these vegetables also contain substances that impair the body’s ability to absorb calcium. “You’d have to eat approximately nine cups of broccoli a day to meet the recommended intake for calcium,” says Story. Boys and girls aged nine to eighteen are advised to consume one thousand three hundred milligrams of calcium per day. That’s equivalent to about four and a half eight-ounce glasses of low-fat milk.

Unfortunately, two-thirds of adolescent girls in the United States fail to meet this requirement, something that Story and other dietitians call a serious public-health problem. According to a survey from the U.S. Department of Agriculture, more and more teenagers are giving up milk in favor of other drinks—mostly soft drinks. Little more than half the teenagers in the poll said they drank milk regularly, as opposed to three-fourths of 1970s youngsters. The National Institutes of Health supports the use of supplements for young people who don’t get sufficient calcium through their diet. For optimal absorption, no more than five hundred milligrams should be taken at one time. Your pediatrician can guide you as to the appropriate dosage and dosing schedule. Because adolescents utilize calcium relatively efficiently, they may be best off ingesting the tablets between meals.

Calcium Sources

• Most foods in the milk group: milk and dishes made with milk, such as puddings and soups.
• Cheeses: mozzarella, cheddar, Swiss, Parmesan, cottage cheese.
• Yogurt.
• Canned fish with soft bones, including sardines, anchovies, salmon.
• Dark-green leafy vegetables, such as kale, mustard greens, turnip greens, bok-choy.
• Tofu, if processed with calcium sulfate.
• Tortillas made from lime-processed corn.
• Calcium-fortified juice, bread, cereal.

Other Ways For Teens To Build Strong Bones

Eat dairy products and other foods fortified with vitamin D. Vitamin D supports bone development by increasing the body’s absorption of calcium from food. Most of us get all the vitamin D we need from everyday exposure to the sun; the rays trigger an internal chemical reaction, producing vitamin D.

For kids who aren’t getting enough calcium, make use of calcium-fortified milk, orange juice, cereals and granola bars. Some of these products contain so much calcium that a single serving takes a youngster halfway to her recommended daily value.

Your teen isn’t a milk drinker? There are other ways to obtain calcium through the diet. “Many adolescents don’t like milk, especially girls,” says dietitian Mary Story. Try tempting your son or daughter with chocolate-flavored skim milk. You can also disguise milk by adding it to soups, puddings, baked products, sauces and stews.

Alternatives to milk include cheese and yogurt. Eight ounces of yogurt and two ounces of cheese contains about the same amount of calcium as eight ounces of milk and therefore each would equal one serving. Half a cup of cottage cheese, however, is lower in the mineral and counts as half a serving.

Go easy on the salt. Besides its association with high blood pressure (hypertension), which is a risk factor in heart disease, kidney disease and stroke, a diet high in salt may deprive the body of calcium by increasing the amount excreted in the urine. Since about 75 percent of the salt we eat has already been added to the various processed foods in our diet, this means not just holding back on the use of the salt shaker, but also cutting down on fast foods and other processed foods, as well as high sodium seasonings like soy sauce, bouillon cubes, meat tenderizer, tamari sauce and Worcestershire sauce.

Stay physically active. Adolescents’ bones respond to weight-bearing exercise by growing stronger and denser. Any activity that gets your teenager up and moving will do, whether it’s jogging, dancing, walking the dog, bowling or jumping jacks.

Don’t smoke tobacco or drink alcohol. In addition to their many other detrimental effects, cigarettes and alcohol decrease bone mass.