• Bonemeal, Calcium Aspartate, Calcium Carbonate, Calcium Chelate, Calcium Citrate, Calcium Citrate Malate, Calcium Gluconate, Calcium Lactate, Calcium Orotate, Dolomite, Oyster Shell Calcium, Tricalcium Phosphate
Calcium is the most abundant mineral in the body, making up nearly 2% of total body weight. More than 99% of the calcium in your body is found in your bones, but the other 1% is perhaps just as important for good health. Many enzymes depend on calcium in order to work properly, as do your nerves, heart, and blood-clotting mechanisms.
To build bone, you need to have enough calcium in your diet. But in spite of calcium-fortified orange juice and the best efforts of the dairy industry, most Americans are calcium deficient.
One of the most important uses of calcium is to help prevent and treat osteoporosis, the progressive loss of bone mass to which
Other meaningful evidence suggests that calcium may have an additional important use: reducing PMS symptoms.
Although there are some variations between recommendations issued by different groups, the official US and Canadian recommendations for daily intake of calcium are as follows:
- 0-6 months: 210 mg
- 7-12 months: 270 mg
- 1-3 years: 500 mg
- 4-8 years: 800 mg
- Males and Females
- 9-18 years: 1,300 mg
- 19-50 years: 1,000 mg
- 51 years and older: 1,200 mg
- Pregnant and Nursing Women
- Under 19 years: 1,300 mg
- 19 years and older: 1,000 mg
To absorb calcium, your body also needs an adequate level of vitamin D (for more information, see the article on Vitamin D
Various medications may impair calcium absorption or metabolism, either directly or through effects on vitamin D. People who use these may benefit by taking extra calcium and vitamin D. Implicated medications include
Milk, cheese, and other dairy products are excellent sources of calcium. Other good sources include orange juice or soy milk fortified with calcium, fish canned with its bones (such as sardines), dark green vegetables, nuts and seeds, and calcium-processed tofu.
Many forms of calcium supplements are available on the market, each with its own advantages and disadvantages.
Naturally Derived Forms of Calcium
These forms of calcium come from bone, shells, or the earth: bonemeal, oyster shell, and dolomite. Animals concentrate calcium in their shells, and calcium is found in minerals in the earth. These forms of calcium are economical, and you can get as much as 500 mg to 600 mg in one tablet. However, there are concerns that the natural forms of calcium supplements may contain significant amounts of lead.
Refined Calcium Carbonate
This is the most common commercial calcium supplement, and it is also used as a common antacid. Calcium carbonate is one of the least expensive forms of calcium, but it can cause constipation and bloating, and it may not be well absorbed by people with reduced levels of stomach acid. Taking it with meals improves absorption because stomach acid is released to digest the food.
Chelated calcium is calcium bound to an organic acid (citrate, citrate malate, lactate, gluconate, aspartate, or orotate). The chelated forms of calcium offer some significant advantages and disadvantages compared with calcium carbonate.
Certain forms of chelated calcium (calcium citrate and calcium citrate malate) are widely thought to be significantly better absorbed and more effective for osteoporosis treatment than calcium carbonate. However, while some studies support this belief,
One study found that calcium citrate malate in orange juice is markedly better absorbed than tricalcium phosphate/calcium lactate in orange juice.
A form of calcium called active absorbable algal calcium (AAACa) has also been promoted as superior to calcium carbonate, but the study upon which claims of benefit are founded actually used quite questionable statistical methods (technically, post-hoc subgroup analysis).
Chelated calcium is much more expensive and bulkier than calcium carbonate. In other words, you have to take larger pills, and more of them, to get enough calcium. It is not at all uncommon to need to take five or six large capsules daily to supply the necessary amount, a quantity some people may find troublesome.
Unlike some supplements, calcium is not taken at extra high doses for special therapeutic benefit. Rather, for all its uses, it should be taken in the amounts listed under Requirements/Sources, along with the recommended level of vitamin D. (See the article on vitamin D
Calcium absorption studies have found evidence that your body can't absorb more than 500 mg of calcium at one time.
It isn't possible to put all the calcium you need in a single
Although the calcium present in some antacids or supplements may alter the absorption of
According to most, though not all studies, use of calcium (especially in the form of calcium citrate) combined with vitamin D
A rather surprising potential use of calcium came to light when a large, well-designed study found that calcium is an effective treatment for
Some, but not all, observational and intervention studies have found evidence that calcium supplementation may reduce the risk of colon
Individuals who are deficient in calcium may be at greater risk of developing
Calcium supplementation has also been tried as a treatment to prevent
Finally, calcium is also sometimes recommended for
What Is the Scientific Evidence for Calcium?
A number of double-blind, placebo-controlled studies
Calcium and vitamin D supplementation may help bones heal that have become fractured due to bone thinning.
Calcium supplements may do a better job of strengthening bones when people have relatively high protein intake.
Calcium supplementation could, in theory, be useful for young girls as a way to "put calcium in the bank"—building up a supply for the future in order to prevent later osteoporosis. However, surprisingly, the benefits seen in studies have been modest to nonexistent, and this approach may only produce results when exercise is also increased.
One study found that in calcium-deficient pregnant women, calcium supplements can improve the bones of their unborn children.
Evidence suggests that the use of calcium combined with vitamin D can help protect against the bone loss caused by corticosteroid drugs, such as prednisone. A review of five studies covering a total of 274 participants reported that calcium and vitamin D supplementation significantly prevented bone loss in corticosteroid-treated individuals.
There is some evidence that essential fatty acids may enhance the effectiveness of calcium. In one study, 65 postmenopausal women were given calcium along with either placebo or a combination of omega-6 fatty acids (from
Premenstrual Syndrome (PMS)
According to a large and well-designed study published in a 1998 issue of
American Journal of Obstetrics and Gynecology,
calcium supplements are a simple and effective treatment for a wide variety of
In a 12-month study of 223 postmenopausal women, use of calcium citrate at a dose of 1 g daily improved the ratio of HDL (“good”)
A 4-year, double-blind, placebo-controlled study followed 832 individuals with a history of colon polyps.
However, a gigantic (36,282 participant), very long-term (average 7 years) study of postmenopausal women failed to find that calcium carbonate supplements at a dose of 1,000 mg daily had any effect on the incidence of colon cancer.
In general, it's safe to take up to 2,500 mg of calcium daily, although this is more than you need. 93,119
Note: If you have cancer, hyperparathyroidism, or sarcoidosis, you should take calcium only under a physician's supervision.
Some evidence hints that use of calcium supplements might slightly increase
There is weak, preliminary evidence that calcium supplementation in healthy, post-menopausal women may slightly increase the risk of cardiovascular events, such as myocardial infarction. However, it remains far from clear whether this possible risk outweighs the benefits of calcium supplementation in this population.
Large observational studies have found that, in men, higher intakes of calcium are associated with an increased risk of prostate cancer.
Calcium supplements combined with high doses of vitamin D might interfere with some of the effects of drugs in the calcium channel blocker family.
Concerns have been raised that the aluminum in some antacids may not be good for you.
When taken over the long term, thiazide diuretics tend to increase levels of calcium in the body by decreasing the amount excreted by the body.
Finally, calcium may interfere with the absorption of antibiotics in the tetracycline and fluoroquinolone families as well as thyroid hormone.
Interactions You Should Know About
- You may need more calcium if you are taking:
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Last reviewed February 2008 by EBSCO CAM Medical Review Board
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