Use for Calcium

What is Calcium for and what does it do? Calcium is the most abundant mineral in the human body. Of the two to three pounds of calcium contained in the average body, 99% is located in the bones and teeth. Calcium is needed to form bones and teeth and is also required for blood clotting, transmission of signals in nerve cells, and muscle contraction. The importance of calcium for preventing osteoporosis is probably its most well-known role.

Although calcium plays at least some minor role in lowering blood pressure, the mechanisms involved appear complex and somewhat unclear. The level of calcium in the blood is tightly regulated by parathyroid hormone (PTH), and low intake of calcium causes elevations in PTH, which in turn have been implicated in the development of hypertension. High calcium intake has also been associated with a reduced risk of cardiovascular disease in postmenopausal women.

By reducing absorption of oxalate, a substance found in many foods, calcium may be able to indirectly reduce the risk of kidney stones. However, people with a history of kidney stones must talk with a doctor before supplementing with calcium because such supplementation might actually increase the risk of forming stones for the small number of people who absorb too much calcium.

Calcium also appears to partially bind some fats and cholesterol in the gastrointestinal tract. Perhaps as a result, some older research suggests that calcium supplementation may help lower cholesterol levels.

Where is Calcium found? Most dietary calcium comes from dairy products. Other good sources include sardines, canned salmon, green leafy vegetables and tofu.

Who is likely to be deficient? Severe deficiency of either calcium or vitamin D leads to a condition called rickets in children and osteomalacia in adults. Since vitamin D is required for calcium absorption, people with conditions causing vitamin D deficiency (e.g., pancreatic insufficiency) may develop a deficiency of calcium as well. Vegans (pure vegetarians), people with dark skin, those who live in northern climates, and people who stay indoors almost all the time are more likely to be vitamin D deficient, than are other people. Vegans often eat less calcium and vitamin D than do other people. Most people eat well below the recommended amount of calcium. This lack of dietary calcium is thought to contribute to the risk of osteoporosis, particularly in white and Asian women.

How much is usually taken? The National Academy of Sciences has established guidelines for calcium that are 25-50% higher than previous recommendations. For ages 19 to 50, calcium intake is recommended to be 1,000 mg daily; for adults over age 51, the recommendation is 1,200 mg daily. General recommendations for higher daily intakes (1,200-1,500 mg) usually include the calcium most people consume from their diets. Studies indicate the average daily amount of calcium consumed by Americans is about 500-1,000 mg.

Are there any side effects or interactions? Constipation, bloating, and gas are sometimes reported with the use of calcium supplements. A very high intake of calcium from dairy products plus supplemental calcium carbonate was reported in the past to cause a condition called "milk alkali syndrome." This toxicity is rarely reported today because most medical doctors no longer tell people with ulcers to use this approach as treatment for their condition.

People with hyperparathyroidism, chronic kidney disease, or kidney stones should not supplement with calcium without consulting a physician. For other adults, the highest amount typically suggested by doctors (1,200 mg per day) is considered quite safe.

Calcium competes for absorption with a number of other minerals. Therefore, people taking calcium for more than a few weeks should also take a multimineral supplement.

Vitamin D’s most important role is maintaining blood levels of calcium. Therefore, many doctors recommend that those supplementing with calcium also supplement with 400 IU of vitamin D per day.