In childhood, not getting enough calcium may interfere with growth. A severe deficiency may keep children from reaching their potential adult height. Even a mild deficiency over a lifetime can affect bone density and bone loss, which increases the risk for osteoporosis as an adult.
If you do not consume enough calcium, your body will draw from the storage in your bones in order to supply enough calcium for its other functions: nerve transmission, muscle contraction, heartbeat, and blood clotting.
Very large doses over a prolonged period of time may cause kidney stones and poor kidney function. Your body may not absorb other minerals, such as
zinc, properly. These problems could occur from consuming too much through a calcium supplement, not from milk or other calcium-rich foods. The tolerable upper intake level (UL) depends on age.
Dairy foods—milk, yogurt, and some cheeses—are the best dietary sources of calcium. These foods are also rich in vitamin D, which helps the body absorb calcium.
Yogurt, plain, low fat
Mozzarella cheese, part skim
Cottage cheese, 1% milkfat
Frozen yogurt, soft serve
Sardines, canned in oil with bones
Salmon, pink, canned solids with bone
Pudding, chocolate, ready to eat
Orange juice, calcium-fortified
Absorption of calcium from some other dietary sources is not as great as that from dairy foods. Specifically, dark green vegetables contain oxalates, and grains contain phytates, which can bind with calcium and decrease their absorption.
Read food labels to determine the specific calcium levels of these foods.
Calcium is essential to build and maintain strong bones at all stages of life. Bone growth begins at conception, and bones grow longer and wider until well into the 20s. After this type of growth is complete, bones gain in strength and density as they continue to build up to peak bone mass by about age 30. From this point on, as a natural part of the aging process, bones slowly lose mass. Calcium is essential to slow this natural loss and stave off the onset of osteoporosis—a disease in which bones become fragile and more likely to break.
If you are unable to meet your calcium needs through dietary sources, consider a calcium supplement. Some points to remember when choosing and using a calcium supplement include:
Check the label because the amount of calcium differs among products.
Avoid supplements with dolomite or bone meal. They may contain lead.
Check your vitamin D intake, too. This vitamin is essential for absorption of calcium. Milk is a great source of vitamin D, as is sunlight.
If you take both calcium and iron supplements or a multivitamin with iron, take them at different times of the day. They can impair each other's absorption. This is also true of chromium, manganese, magnesium, and zinc.
Do not take more than 500 mg of calcium at a time. Taking the calcium with food can help absorption.