Calcium

Calcium to treat and prevent osteoporosis.
Calcium requirements:

Age

Calcium Requirement

9–18

1,300 mg/day

19–50

1,000 mg/day

51+

1,200 mg/day

Pregnant women 1,000 mg (1,300 mg if under 19 years old)
Nursing women 1,000 mg (1,300 mg if under 19 years old)

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.

To maintain your bones, you need to have enough calcium in your diet. Most Americans are calcium deficient. Common calcium containing foods include milk, cheese, yogurt, and calcium-fortified orange juice. Soy milk fortified with calcium, fish canned with its bones (e.g., sardines), dark green vegetables, nuts and seeds, and calcium-processed tofu are additional sources. Three servings of calcium containing foods generally provide about 1000mg. of calcium. Additional calcium can be supplied by supplements. Vitamin D helps in calcium absorption, and 400 IU’s are generally suggested.

Naturally Derived Forms of Calcium
These forms of calcium come from bone, or shells,: 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 to 600 mg in one tablet. However, there are concerns that the natural forms of calcium supplements may contain significant amounts of lead. The level of contamination has decreased in recent years, but still may present a health risk. The lead concentration should always be less than 2 parts per million.

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
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. 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.

The form of calcium found in beverages is usually the chelated form, calcium citrate malate, or a slightly less well absorbed form, tricalcium phosphate.

Click for a printable Calcium Chart including supplements and food sources of calcium.

Therapeutic Dosages

Calcium absorption studies have found that your body can't absorb more than 500 mg of calcium at one time. Therefore, it is most efficient to take your total daily calcium in two or more doses.

It isn't possible to put all the calcium you need in a single multivitamin/mineral tablet, so this is one supplement that should be taken on its own.

Furthermore, calcium may interfere with the absorption of many minerals. It is best to take your multivitamin at a separate time from your calcium supplement.

Calcium may also interfere with iron absorption.

What Is the Scientific Evidence for Calcium?

Osteoporosis
Numerous studies indicate that calcium supplements are useful in preventing and slowing osteoporosis, the progressive loss of bone mass as we age. Calcium supplementation at the recommended dosages appears to reduce bone loss in postmenopausal women in every part of the body except the spine. When vitamin D is taken along with calcium, it may be possible not only to slow down but actually reverse osteoporosis, in the spine as well as in other bones. However, calcium and vitamin D use must be continual. Improvements in bone rapidly disappear once the supplements are stopped.

Calcium supplements, at least calcium-citrate malate, may do a better job of strengthening bones in individuals with relatively high protein intake.

Calcium supplementation is also useful for young girls as a way to "put calcium in the bank"—building up a supply for the future. However, exercise may be even more important.

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.

For example, in a 2-year double-blind, placebo-controlled study that followed 65 individuals with rheumatoid arthritis taking low-dose corticosteroids, daily supplementation with 1,000 mg of calcium and 500 IU of vitamin D reversed steroid-induced bone loss, causing a net bone gain.

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 evening primrose oil) and omega-3 fatty acids (from fish oil) for a period of 18 months. At the end of the study period, the group receiving essential fatty acids had higher bone density and fewer fractures than the placebo group. However, a 12-month double-blind trial of 42 postmenopausal women found no benefit. The explanation for the discrepancy may lie in the differences between the women studied. The first study involved women living in nursing homes, while the second studied healthier women living on their own. The latter group of women may have been better nourished, and already received enough essential fatty acids in their diet.

Safety Issues

In general, it's safe to take up to 2,500 mg of calcium daily, although this is more than you need. Greatly excessive intake of calcium can cause numerous side effects, including dangerous or painful deposits of calcium within the body.

If you have cancer, hyperparathyroidism, or sarcoidosis, you should take calcium only under a physician's supervision.

People with kidney stones or a history of kidney stones are also often warned not to take supplemental calcium. The reason for this caution is that kidney stones are commonly made of calcium oxalate crystals. However, studies have found that increased intake of calcium from food actually reduces the risk of kidney stones. Calcium supplements, on the other hand, might slightly increase kidney stone risk, especially if they are not taken with meals. The bottom line: avoiding calcium supplements may still be appropriate for certain people with a tendency to develop kidney stones.