The Romans used lime (calcium oxide), clacked lime (calcium hydroxide), and hydraulic cement in construction works. Calcium (Latin calx, meaning "lime") was first isolated in its metallic form by Sir Humphrey Davy in 1808 through the electrolysis of a mixture of calcium oxide and mercury oxide.
Chelated calcium refers to the way in which calcium is chemically combined with another substance. Calcium citrate is an example of such a chelated preparation. Calcium may also be combined with other substances to form preparations such as calcium lactate or calcium gluconate. Calcium carbonate can be refined from limestone, natural elements of the earth, or from shell sources, such as oyster. Shell sources are often described on the label as a "natural" source. Calcium carbonate from oyster shells is not "refined" and can contain variable amounts of lead.
Calcium is the most abundant mineral in the human body and has several important functions. More than 99% of total body calcium is stored in the bones and teeth where it supports the structure. The remaining 1% is found throughout the body in blood, muscle, and the intracellular fluid. Calcium is needed for muscle contraction, blood vessel constriction and relaxation, the secretion of hormones and enzymes, and nervous system signaling. A constant level of calcium is maintained in body fluid and tissues so that these vital body processes function efficiently.
The body gets the calcium it needs in two ways. One method is dietary intake of calcium-rich foods including dairy products, which have the highest concentration per serving of highly absorbable calcium, and dark, leafy greens or dried beans, which have varying amounts of absorbable calcium. Calcium is an essential nutrient required in substantial amounts, but many diets are deficient in calcium.
The other way the body obtains calcium is by extracting it from bones. This happens when blood levels of calcium drop too low and dietary calcium is not sufficient. Ideally, the calcium that is taken from the bones will be replaced when calcium levels are replenished. However, simply eating more calcium-rich foods does not necessarily replace lost bone calcium, which leads to weakened bone structure.
Hypocalcaemia is defined as a low level of calcium in the blood. Symptoms of this condition include sensations of tingling, numbness, and muscle twitches. In severe cases, tetany (muscle spasms) may occur. Hypocalcaemia is more likely to be due to a hormonal imbalance, which regulates calcium levels, rather than a dietary deficiency. Excess calcium in the blood can cause nausea, vomiting, and calcium deposition in the heart and kidneys. This usually results from excessive doses of vitamin D and can be fatal in infants.
The Surgeon General's 2004 report "Bone Health and Osteoporosis" stated that calcium has been singled out as a major public health concern today because it is critically important to bone health and the average American consumes levels of calcium that are far below the amount recommended. Vitamin D is important for good bone health because it aids in the absorption and utilization of calcium. There is a high prevalence of vitamin D insufficiency in nursing home residents, hospitalized patients, and adults with hip fractures.
Calcium supplements are widely used to reduce bone resorption in osteoporosis, and many studies support this use. Calcium supplementation is also used for colorectal neoplasia and in pregnancy.
EvidenceTable
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Antacid (calcium carbonate) (Grade: A)
Calcium carbonate is an FDA (U.S. Food and Drug Administration) approved over-the-counter (OTC) drug used to treat gastric hyperacidity (high acid levels in the stomach).
Calcium carbonate is an FDA (U.S. Food and Drug Administration) approved over-the-counter (OTC) drug used to treat gastric hyperacidity (high acid levels in the stomach).
Bone loss (prevention) (Grade: A)
Multiple studies of calcium supplementation in the elderly and postmenopausal women have found that high calcium intakes can help reduce the loss of bone density. Studies indicated that bone loss could be prevented in many areas including ankles, hips, and spine.
Multiple studies of calcium supplementation in the elderly and postmenopausal women have found that high calcium intakes can help reduce the loss of bone density. Studies indicated that bone loss could be prevented in many areas including ankles, hips, and spine.
Cardiopulmonary resuscitation (CPR) (Grade: A)
Calcium chloride may be given intravenously (IV) by a qualified healthcare professional in cardiac resuscitation, particularly after open-heart surgery, when epinephrine fails to improve weak or ineffective myocardial contractions. Calcium chloride is contraindicated for cardiac resuscitation in the presence of ventricular fibrillation. CPR with calcium chloride should only be done under the supervision of a qualified healthcare professional.
Calcium chloride may be given intravenously (IV) by a qualified healthcare professional in cardiac resuscitation, particularly after open-heart surgery, when epinephrine fails to improve weak or ineffective myocardial contractions. Calcium chloride is contraindicated for cardiac resuscitation in the presence of ventricular fibrillation. CPR with calcium chloride should only be done under the supervision of a qualified healthcare professional.
Deficiency (calcium) (Grade: A)
Calcium gluconate is used to treat conditions arising from calcium deficiencies such as hypocalcaemic (low blood calcium) tetany (muscle spasms), hypocalcaemia related to hypoparathyroidism (low levels of the parathyroid hormone), and hypocalcaemia due to rapid growth or pregnancy. It is also used for the treatment of hypocalcaemia for conditions requiring a prompt increase in plasma calcium levels (e.g., tetany in newborns and tetany due to parathyroid deficiency, vitamin D deficiency, and alkalosis) and for the prevention of hypocalcaemia during exchange transfusions. Treatment of hypocalcaemia should only be done under supervision of a qualified healthcare professional.
Calcium gluconate is used to treat conditions arising from calcium deficiencies such as hypocalcaemic (low blood calcium) tetany (muscle spasms), hypocalcaemia related to hypoparathyroidism (low levels of the parathyroid hormone), and hypocalcaemia due to rapid growth or pregnancy. It is also used for the treatment of hypocalcaemia for conditions requiring a prompt increase in plasma calcium levels (e.g., tetany in newborns and tetany due to parathyroid deficiency, vitamin D deficiency, and alkalosis) and for the prevention of hypocalcaemia during exchange transfusions. Treatment of hypocalcaemia should only be done under supervision of a qualified healthcare professional.
High blood phosphorous level (Grade: A)
Hyperphosphatemia (high phosphate level in the blood) is associated with increased cardiovascular mortality in adult dialysis patients. Calcium carbonate or acetate can be used effectively as phosphate binders. Use may increase calcium-phosphate products in blood. Treatment of high blood phosphorous levels should only be done under supervision of a qualified healthcare professional.
Hyperphosphatemia (high phosphate level in the blood) is associated with increased cardiovascular mortality in adult dialysis patients. Calcium carbonate or acetate can be used effectively as phosphate binders. Use may increase calcium-phosphate products in blood. Treatment of high blood phosphorous levels should only be done under supervision of a qualified healthcare professional.
Osteoporosis (Grade: A)
Osteoporosis is a disorder of the skeleton in which bone strength is reduced, resulting in an increased risk of fracture. Although osteoporosis is most commonly diagnosed in white postmenopausal women, women of other racial groups and ages, men, and children may also develop osteoporosis.
Osteoporosis is a disorder of the skeleton in which bone strength is reduced, resulting in an increased risk of fracture. Although osteoporosis is most commonly diagnosed in white postmenopausal women, women of other racial groups and ages, men, and children may also develop osteoporosis.
Toxicity (magnesium) (Grade: A)
Calcium gluconate is used in the treatment of hypermagnesemia (high levels of magnesium in the blood). Case studies suggest intravenous calcium can aid in the improvement of symptoms. Treatment of magnesium toxicity should only be done under supervision of a qualified healthcare professional.
Calcium gluconate is used in the treatment of hypermagnesemia (high levels of magnesium in the blood). Case studies suggest intravenous calcium can aid in the improvement of symptoms. Treatment of magnesium toxicity should only be done under supervision of a qualified healthcare professional.
Black widow spider bite (Grade: B)
Calcium supplementation is used in the treatment of black widow spider bites to relieve muscle cramping in combination with antiserum, analgesics (pain relievers), and muscle relaxants. Treatment of a black widow spider bite should only be done under the supervision of a qualified healthcare professional.
Calcium supplementation is used in the treatment of black widow spider bites to relieve muscle cramping in combination with antiserum, analgesics (pain relievers), and muscle relaxants. Treatment of a black widow spider bite should only be done under the supervision of a qualified healthcare professional.
High blood potassium level (Grade: B)
Calcium gluconate may aid in antagonizing the cardiac toxicity and arrhythmia (abnormal heart rhythm) associated with hyperkalemia (high blood potassium), provided the patient is not receiving digitalis drug therapy. Treatment of hyperkalemia should only be done under supervision of a qualified healthcare professional.
Calcium gluconate may aid in antagonizing the cardiac toxicity and arrhythmia (abnormal heart rhythm) associated with hyperkalemia (high blood potassium), provided the patient is not receiving digitalis drug therapy. Treatment of hyperkalemia should only be done under supervision of a qualified healthcare professional.
High blood pressure (Grade: B)
Several studies have found that introducing calcium to the system can have hypotensive (blood pressure lowering) effects. These studies indicate that high calcium levels lead to sodium loss in the urine, and lowered parathyroid hormone (PTH) levels, both of which result in the lowering of blood pressure. However, one study found that these results did not hold true for middle-aged patients with mild to moderate essential hypertension.
Several studies have found that introducing calcium to the system can have hypotensive (blood pressure lowering) effects. These studies indicate that high calcium levels lead to sodium loss in the urine, and lowered parathyroid hormone (PTH) levels, both of which result in the lowering of blood pressure. However, one study found that these results did not hold true for middle-aged patients with mild to moderate essential hypertension.
Premenstrual syndrome (PMS) (Grade: B)
There is a link between lower dietary intake of calcium and symptoms of premenstrual syndrome. Calcium supplementation has been suggested in various clinical trials to decrease overall symptoms associated with PMS, such as depressed mood, water retention, and pain.
There is a link between lower dietary intake of calcium and symptoms of premenstrual syndrome. Calcium supplementation has been suggested in various clinical trials to decrease overall symptoms associated with PMS, such as depressed mood, water retention, and pain.
Bone stress injury prevention (Grade: C)
Calcium supplementation above normal daily dietary intake did not reduce stress fractures in men. Thus calcium supplementation may not be effective in preventing stress fractures but further studies must be done to validate these results.
Calcium supplementation above normal daily dietary intake did not reduce stress fractures in men. Thus calcium supplementation may not be effective in preventing stress fractures but further studies must be done to validate these results.
Colorectal cancer (Grade: C)
Colorectal cancer is the most common gastrointestinal cancer and the second leading cause of cancer deaths in the United States. Colorectal cancer is caused by a combination of genetic and environmental factors, but the degree to which these two factors influence the risk of colon cancer in individuals varies. Most large prospective studies have found increased calcium intake to be only weakly associated with a decreased risk of colorectal cancer. Further studies are needed to verify these results. Treatment of colorectal cancer should only be done under the supervision of a qualified healthcare professional.
Colorectal cancer is the most common gastrointestinal cancer and the second leading cause of cancer deaths in the United States. Colorectal cancer is caused by a combination of genetic and environmental factors, but the degree to which these two factors influence the risk of colon cancer in individuals varies. Most large prospective studies have found increased calcium intake to be only weakly associated with a decreased risk of colorectal cancer. Further studies are needed to verify these results. Treatment of colorectal cancer should only be done under the supervision of a qualified healthcare professional.
Growth (mineral metabolism in very low birth weight infants) (Grade: C)
Growth of very low birth weight infants correlates with calcium intake and retention in the body. It is possible that human milk fortifiers commonly used may have inadequate levels of calcium for infants of very low birth weight. Bone mineralization is also lower in very low birth weight infants at theoretical term than in infants born at term. Use of a formula containing higher levels of calcium has been suggested to allow improved bone mineralization in these infants.
Growth of very low birth weight infants correlates with calcium intake and retention in the body. It is possible that human milk fortifiers commonly used may have inadequate levels of calcium for infants of very low birth weight. Bone mineralization is also lower in very low birth weight infants at theoretical term than in infants born at term. Use of a formula containing higher levels of calcium has been suggested to allow improved bone mineralization in these infants.
High blood pressure (pregnancy-induced) (Grade: C)
For the general population, meeting current recommendations for calcium intake during pregnancy may help prevent pregnancy-induced high blood pressure (PIH). Further research is required to determine whether women at high risk for PIH would benefit from calcium supplementation above the current recommendations. Treatment of PIH should only be done under supervision of a qualified healthcare professional.
For the general population, meeting current recommendations for calcium intake during pregnancy may help prevent pregnancy-induced high blood pressure (PIH). Further research is required to determine whether women at high risk for PIH would benefit from calcium supplementation above the current recommendations. Treatment of PIH should only be done under supervision of a qualified healthcare professional.
Hyperparathyroidism (secondary) (Grade: C)
In patients on hemodialysis, calcium supplementation may reduce secondary hyperparathyroidism (high blood level s of parathyroid hormone due to another medical condition or treatment). Treatment of hyperparathyroidism should only be done under the supervision of a qualified healthcare professional.
In patients on hemodialysis, calcium supplementation may reduce secondary hyperparathyroidism (high blood level s of parathyroid hormone due to another medical condition or treatment). Treatment of hyperparathyroidism should only be done under the supervision of a qualified healthcare professional.
Lead toxicity (acute symptom management) (Grade: C)
A chelating treatment of calcium has been suggested to reduce blood levels of lead in cases of lead toxicity. Reduced symptoms have been observed in most, but not all, patient case reports and case histories. Adequate calcium intake appears to be protective against lead toxicity. Treatment of lead toxicity should only be done under the supervision of a qualified healthcare professional.
A chelating treatment of calcium has been suggested to reduce blood levels of lead in cases of lead toxicity. Reduced symptoms have been observed in most, but not all, patient case reports and case histories. Adequate calcium intake appears to be protective against lead toxicity. Treatment of lead toxicity should only be done under the supervision of a qualified healthcare professional.
Osteomalacia / rickets (Grade: C)
Rickets and osteomalacia (bone softening) are commonly thought of as diseases due to vitamin D deficiency; however, calcium deficiency may also be another cause in sunny areas of the world where vitamin D deficiency would not be expected. Calcium gluconate is used as an adjuvant in the treatment of rickets and osteomalacia, as well as a single therapeutic agent in non-vitamin D deficient rickets. Research continues into to the importance of calcium alone in the treatment and prevention of rickets and osteomalacia. Treatment of rickets and osteomalacia should only be done under the supervision of a qualified healthcare professional.
Rickets and osteomalacia (bone softening) are commonly thought of as diseases due to vitamin D deficiency; however, calcium deficiency may also be another cause in sunny areas of the world where vitamin D deficiency would not be expected. Calcium gluconate is used as an adjuvant in the treatment of rickets and osteomalacia, as well as a single therapeutic agent in non-vitamin D deficient rickets. Research continues into to the importance of calcium alone in the treatment and prevention of rickets and osteomalacia. Treatment of rickets and osteomalacia should only be done under the supervision of a qualified healthcare professional.
Osteoporosis prevention (steroid-induced) (Grade: C)
Calcium supplementation in patients on long-term, high-dose inhaled steroids for asthma may reduce bone loss due to steroid intake. Treatment using the prescription drug pamidronate with calcium has been shown to be superior to calcium alone in the prevention of corticosteroid-induced osteoporosis. Inhaled steroids have been reported to disturb normal bone metabolism, and they are associated with a decrease in bone mineral density. Results suggest that long-term administration of high-dose inhaled steroid induces bone loss that is preventable with calcium supplementation with or without the prescription drug etidronate. Long-term studies involving more patients should follow to confirm these preliminary findings.
Calcium supplementation in patients on long-term, high-dose inhaled steroids for asthma may reduce bone loss due to steroid intake. Treatment using the prescription drug pamidronate with calcium has been shown to be superior to calcium alone in the prevention of corticosteroid-induced osteoporosis. Inhaled steroids have been reported to disturb normal bone metabolism, and they are associated with a decrease in bone mineral density. Results suggest that long-term administration of high-dose inhaled steroid induces bone loss that is preventable with calcium supplementation with or without the prescription drug etidronate. Long-term studies involving more patients should follow to confirm these preliminary findings.
Prostate cancer (increased risk) (Grade: C)
The lack of agreement among these studies suggests complex interactions among risk factors for prostate cancer. Until the relationship between calcium and prostate cancer is clarified, it is reasonable for men to consume recommended intakes as per the Food and Nutrition Board of the Institute of Medicine. Treatment of prostate cancer should only be done under the supervision of a qualified healthcare professional.
The lack of agreement among these studies suggests complex interactions among risk factors for prostate cancer. Until the relationship between calcium and prostate cancer is clarified, it is reasonable for men to consume recommended intakes as per the Food and Nutrition Board of the Institute of Medicine. Treatment of prostate cancer should only be done under the supervision of a qualified healthcare professional.
Weight loss (Grade: C)
Diets with higher calcium density (high levels of calcium per total calories) have been associated with a reduced incidence of being overweight or obese in several studies. While more research is needed to understand the relationships between calcium intake and body fat, these findings emphasize the importance of maintaining an adequate calcium intake while attempting to diet or lose weight.
Diets with higher calcium density (high levels of calcium per total calories) have been associated with a reduced incidence of being overweight or obese in several studies. While more research is needed to understand the relationships between calcium intake and body fat, these findings emphasize the importance of maintaining an adequate calcium intake while attempting to diet or lose weight.
Vaginal disorders (atrophy, wasting or thinning or the vaginal tissue) (Grade: D)
Stopping treatment with topical hormone replacement therapy and switching to treatment with calcium plus vitamin D made vaginal atrophy worse in one study. Increases in painful or difficult intercourse and urinary leaks were reported. Menopausal complaints of hot flashes and night sweats were also worse than before calcium plus vitamin D therapy.
Stopping treatment with topical hormone replacement therapy and switching to treatment with calcium plus vitamin D made vaginal atrophy worse in one study. Increases in painful or difficult intercourse and urinary leaks were reported. Menopausal complaints of hot flashes and night sweats were also worse than before calcium plus vitamin D therapy.
