What food source is the nutrient found in?

Dairy products are the best source for calcium. Dark green leafy vegetables and fish with edible bones, such as salmon, are also good sources. Many breakfast cereals and orange juice brands have added calcium.

Some foods can interfere with the absorption calcium. Foods that may do this include:

High protein intake can also interfere with the body's uptake of calcium.

Sources of calcium include:

How does the nutrient affect the body?

The most well known function of calcium is to preserve bone density. This process is aided by other key vitamins and minerals including magnesium and vitamin D. Without enough calcium, bones may lose density. This condition is called osteoporosis. More than 25 million Americans, mostly women, suffer from it. This disease puts people at greater risk for hip and other bone fractures. Bones act as a reservoir for calcium. If there is not enough calcium circulating in the blood to meet the body's needs for the mineral, it will be pulled from the bones.

Typically, people keep building up calcium in the bones through their late 20's and early 30's. After age 30 to 35, bones begin to naturally lose minerals such as calcium that give them strength. After age 50, calcium loss from bone becomes even more common, especially among women. The hormone estrogen helps keep calcium in bones. After menopause, a woman's body stops producing estrogen. This increases the loss of calcium from bone . Hormone replacement therapy and weight-bearing exercise such as walking and weight lifting can help maintain bone density in post-menopausal women.

If people get enough calcium in their youth, they can build a healthy reservoir to draw from in later years. Later in life, a person needs to consume enough calcium so that it is not robbed from the bones. Vitamin D also helps the body to absorb calcium into the bones.

Bone health is not the only function of calcium in the body. Calcium is also needed for vital nerve and muscle transmission including the healthy function of the heart. Several recent studies have shown how calcium can help lessen both the physical and emotional symptoms of pre-menstrual syndrome, which is also known as PMS. The mechanism behind this effect is not yet known. It may be because of calcium's close link with certain hormones. The dose used in these studies was 1200 mg a day.