Calcium is one of most important minerals within your body as it provides strength for bones and allows your muscles to contract, among many other functions. A lack of dietary calcium increases your risk of osteoporosis, cardiovascular diseases and muscle dysfunction. Milk, cheese, nuts and some leafy vegetables are excellent sources of calcium, but if you don't eat much of these items then calcium supplementation may be a good idea. Calcium supplements differ in the amount of elemental calcium and their absorbability.
Recommended Amounts
The National Institutes of Health states that the dietary reference intake for adults is between 1,000 and 1,300 mg of calcium per day, depending on your age, sex and whether or not you are pregnant. Calcium deficiency is not thought to be common among Americans and is certainly less common than magnesium deficiency, according to Gordon Wardlaw, author of "Contemporary Nutrition: Functional Approach." Wardlaw also notes that osteoporosis does not develop simply due to a lack of calcium, as vitamin D, the hormone estrogen and the acidity of your tissues also play important roles.
Rich Sources of Elemental Calcium
Calcium is not found free in nature because it quickly forms compounds known as calcium salts. For example, calcium combines with carbon and oxygen to form calcium carbonate or with citric acid to form calcium citrate. The term "elemental calcium" represents the percentage of the supplement that is pure calcium. According to "Nutritional Sciences," calcium carbonate is 40 percent elemental calcium, calcium phosphate contains 38 percent, calcium citrate contains 21 percent and lactate calcium contains 13 percent. For example, a 1,000-mg calcium carbonate tablet contains 400 mg of calcium.
Absorbability
Calcium carbonate is the most used and least expensive type of calcium supplement in North America, but it is not absorbed very well in your intestines. Calcium is absorbed better in highly acidic environments, which explains why calcium citrate is the best absorbed of the calcium supplements. However, as Benjamin Caballero, author of "Guide to Nutritional Supplements" points out, calcium citrate may be up to twice as absorbable as calcium carbonate, but equal sized tablets contain only half as much elemental calcium, so the bioavailability of the two supplements is roughly equivalent. Further, calcium citrate can cost up to 50 percent more than the equivalent amount of calcium carbonate.
Recommendations
Although calcium citrate is usually more expensive, it can be taken without food, so it could be considered more convenient. Calcium carbonate, on the other hand, should always be taken with meals because the release of stomach acid is needed to enhance its absorption. According to "DRI, Dietary Reference Intakes: The Essential Guide to Nutrient Requirements," taking more than 500 mg of elemental calcium at one time is not suggested because your body cannot absorb more than that. Excess calcium is excreted in your urine. Calcium absorption is also affected by the amount of vitamin D and magnesium in your diet, as well as stomach acid and estrogen production. Fluctuations in estrogen production is a main reason why osteoporosis is almost exclusively a female disease.
References
- National Institutes of Health: Office of Dietary Supplements: Calcium Fact Sheet
- "Contemporary Nutrition: Functional Approach"; Gordon M. Wardlaw; 2009
- "Nutritional Sciences"; Michelle McGuire; 2007
- "Guide to Nutritional Supplements"; Benjamin Caballero; 2009
- "DRI, Dietary Reference Intakes: The Essential Guide to Nutrient Requirements"; Jennifer J. Otten et al; 2006
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