Building bones is not just for youngsters. The more we learn about nutrition and health the more we realize that maintaining good bone structure is a lifetime process. Once our bone mass reaches its peak (at about age 30), keeping our bones strong remains vital to good health.

A lot of new research is being published about bone health. Although experts still agree calcium is a key factor, they are now identifying the specific roles of other nutrients in the bone health picture. Calcium's function is part of a carefully orchestrated process that includes magnesium, Vitamin D, selenium, boron, fluoride, and phosphorus.

Still, calcium remains the major focus, because studies show that average calcium intake is less than adequate. The most recent official recommendations, called Dietary Reference Intakes (DRIs), recommend that people over 55 consume 1,200 milligrams (mg). Dairy products are our primary source of calcium as well as Vitamin D, which helps our bodies absorb calcium. Calcium is found in the milk solids portion of these products, irrespective of their fat content. An 8-ounce glass of milk –– whether nonfat, reduced fat or whole  — contains the same amount of calcium, approximately 300 milligrams (mg). Of course, cheeses and yogurt (excluding cottage and cream cheeses) are also good sources of calcium.

Calcium-fortified orange juice is another good option. It provides 300 mg of calcium per 8-ounce. serving and contributes to the five daily servings of fruits and vegetables recommended by health organizations such as the American Institute for Cancer Research (AICR). Fortified breads, tortillas, and cereals can contribute significantly to our daily intake of calcium as well. Be sure to check the labels, because not all of these products are calcium-fortified.

Although kale, broccoli, bok choy, spinach, collard greens, and beans provide less calcium than some other vegetables (40 to 120 mg per cup), their form of calcium is more easily absorbed, compensating for the smaller amount available. They also contain a variety of other important health-promoting substances and should be included in your diet.

Calcium is the most abundant mineral in the body. Although 99 percent of it is in our bones, it works elsewhere in our bodies as well. It manages cell reproduction; regulates muscle contraction and relaxation; keeps the heart beating; moves nutrients between cells; and helps to control blood pressure, blood clotting, and brain function. As if that were not enough, studies have also shown that women who take calcium supplements and eat calcium-rich foods are half as likely to develop kidney cancer as those who do not.

If you do not get enough calcium from your diet, your body takes what it needs from your bones. Since the body first and foremost maintains blood calcium levels, these may be maintained at the expense of bone calcium. Blood calcium levels are therefore not a good test for a person's calcium status.

Consuming the recommended amount of calcium requires some extra effort, especially for those who have an intolerance to the lactose in cow's milk. For the lactose-intolerant, lactose-free milk or an over-the-counter lactase enzyme are two alternatives. A third strategy is learning to limit the amount of lactose at one time to the specific amount your body can handle. (This amount will differ from person to person.) People who do not eat a calcium-rich diet or who are at risk for osteoporosis should discuss the need for further supplementation with their doctor.

Calcium is one of several nutrients that are not wholly absorbed by our body. Even in our food, only about 40 percent of the calcium we consume is actually absorbed, and even less from some supplements. Calcium citrate is considered the most readily absorbed form of calcium. Calcium carbonate also has an acceptable rate of absorption. Check labels on supplements to verify the type and amount of available calcium. For those who have difficulty swallowing large tablets, supplements are also available in both powder and liquid forms, as well as a chewy candy-like product.