Calcium is the fifth most abundant element in the Earth's crust and the most abundant mineral in the human body. Calcium is required for muscle contraction, sending nerve impulses, helping blood to clot, maintaining a normal heart beat and is the foundation of bones and teeth. In fact, 99 percent of the calcium in the body is found in the bones and teeth, and the remaining 1 percent in the blood and tissue. When there is inadequate calcium circulating in the blood, the body will pull calcium from the bones which can lead to low bone mass and eventually osteoporosis.
Calcium Requirements
School age children ages 4 to 8 require 1,000 mg of calcium per day. As children reach puberty, a time of increased growth and development, from age 9 to 18, calcium requirements increase to 1,300 mg each day. During adulthood, ages 19 to 50, calcium requirements drop back to 1,000 mg each day. Adults over the age of 50 require 1,200 mg of calcium per day.
Osteoporosis
As we grow our bones increase in size and mass until we reach our peak bone density at the age of 30. Bone loss occurs as part of the aging process and is prevalent in postmenopausal women, due to the loss of estrogen. Osteoporosis is a condition of porous and fragile bones and, according to the National Osteoporosis Foundation, is a major public health threat. It is estimated that by the year 2020, more that 61 million Americans will be diagnosed with osteoporosis. Factors that can increase the risk of developing osteoporosis include: being female, fair-skinned, inactivity, smoking cigarettes, excessive alcohol intake and having a family history of the disease.
Food Sources
Milk, yogurt and cheese are naturally rich sources of calcium. Dairy foods contribute about 75 percent of the dietary calcium that we need each day. However, there are other sources of calcium as well. Dark green vegetables such as Chinese cabbage, kale and broccoli also contain calcium. Grain products, unless they are fortified, are not the best sources of dietary calcium, but because we eat them frequently, they can contribute to the overall calcium content of the diet. Food such as calcium fortified juices and soy beverages can also be consumed.
Calcium Supplements
Those who have an increased calcium requirement, or who are lactose intolerant or follow a strict vegetarian diet, may need to take a calcium supplement to meet their calcium needs. The two forms of calcium supplements are calcium carbonate and calcium citrate. Calcium carbonate supplements are more widely available and less expensive than calcium citrate. For maximal absorption calcium carbonate supplements should be taken with food. Calcium citrate supplements are more appropriate in individuals with reduced levels of stomach acid and are somewhat better tolerated. The calcium in supplements is best absorbed in amounts less than 500 mg, so you may need to spread out a large dose throughout the day.
Osteoporosis is a disease that begins in childhood. It is best to prevent low bone mass and osteoporosis by consuming enough calcium and being physically active throughout your life.
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