Calcium

background

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 may 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 may 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.
Hypocalcemia 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. Hypocalcemia is more likely to be due to a hormonal imbalance, which regulates calcium levels, rather than a dietary deficiency. Excess calcium in the blood may cause nausea, vomiting, and calcium deposition in the heart and kidneys. This usually results from excessive doses of vitamin D and may 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 suggested. 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 as an antacid, for building bone mineral density, for hyperphosphatemia, hypocalcemia, renal failure, magnesium toxicity, black widow spider bite, fracture prevention, gastrointestinal tract and colorectal cancer prevention, hyperkalemia, hypertension, lead toxicity, osteomalacia (bone softening)/rickets, postsurgical side effects (rectal epithelial hyperproliferation), preeclampsia, premenstrual syndrome (PMS), seizures, arrhythmias, bone diseases, breast cancer prevention, cardiovascular risk reduction, cystic fibrosis, endometrial cancer prevention, fall prevention, growth, childbirth (preterm birth prevention), circulation, hyperparathyroidism, mortality, muscle strength, myocardial infarction, osteoporosis (drug-induced), ovarian cancer prevention, postnatal depression, type 2 diabetes, weight loss, cardiopulmonary resuscitation (CPR), and vaginal disorders. Calcium's use for calcium channel blocker overdose is investigational.

Related Terms

AdvaCAL®, Alka-Mints®, Apo-Cal®, atomic number 20, Bica®, Bo-Ne-Ca®, bone meal, bovine cartilage, Ca, Cal-100®, Calcanate®, Calcefor®, Calci Aid®, Calci-Fresh®, Calcigamma®, Calcilos®, Calcimax®, Calcit®, calcitonin, Calcitridin®, calcitriol, calcium acetate, calcium aspartate, calcium carbonate, calcium chelate, calcium chloride, calcium citrate, calcium citrate malate, Calcium Dago® (Germany), calcium formate, calcium glucepate, calcium gluconate, Calcium Klopfer® (Austria), calcium lactate, calcium lactate gluconate, calcium lactogluconate, calcium orotate, calcium oxalate, Calcium Pharmavit® (Hungary), calcium phosphate, calcium pyruvate, Calcium-Sandoz Forte® (Bulgaria), Calcuren® (Finland), Caldoral® (Colombia), Calmate® 500 (Philippines), CalMax®, Calmicid®, Cal-Quick®, Calsan® (Mexico, Peru, Philippines), Calsup®, Cal-Sup® (New Zealand), Caltab® (Thailand), Caltrate®, Caltrate® (Colombia, Malaysia, Mexico, Puerto Rico, South Africa), Caltrate 600® (Canada, Colombia, Costa Rica, Dominican Republic, Ecuador, El Salvador, Guatemala, Honduras, Nicaragua, Panama, Peru, Venezuela), Cantacid® (Korea), Cartilade®, CC-Nefro 500® (Germany), Chooz®, Chooz Antacid Gum 500® (Israel), Citrical®, coral calcium, dairy products (milk, cheese, yogurt, etc.), dicalcium phosphate, Dimacid®, dolomite, Estroven®, Fixical® (France), Gaviscon®, heated oyster shell-seaweed calcium, hydroxyapatite, intravenous 42Ca, isotopically enriched milk, LeanBalance®, Living Calcium®, Maalox®, Maalox® Quick Dissolve (Canada), magnesium, Netra® (Israel), Neutralin®, Noacid® (Uruguay), nonfat milk, oral 44Ca,Orocal® (France), Os-Cal®, Ospur® Ca 500 (Germany), Osteocal® 500 (France), osteocalcin, Osteomin® (Mexico), OsteoPrime®, Osteo Wisdom®, oyster shell calcium, oyster shell electrolysate (OSE), Pepcid® Complete, Pluscal® (Argentina), Posture-D®, Renacal (Germany), Rocaltrol®, Rolaids®, salmon calcitonin, Sandocal®, shark cartilage, tricalcium phosphate, Tums®, Tums Ultra Assorted Berries® (Israel), Tums Ultra Spearmint® (Israel), Tzarevet X® (Israel), Viactiv®.

evidence table

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 (Grade: A)
Calcium carbonate is an U.S. Food and Drug Administration (FDA) approved over-the-counter (OTC) drug used to treat gastric hyperacidity (high acid levels in the stomach).
Bone density (Grade: A)
Multiple studies of calcium supplementation have found that high calcium intakes may help reduce the loss of bone density. Studies indicated that bone loss could be prevented in many areas including ankles, hips, and spine.
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 may 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.
Hypocalcemia (Grade: A)
Calcium supplementation is used to treat conditions arising from calcium deficiencies such as hypocalcemic (low blood calcium) tetany (muscle spasms), hypocalcemia related to hypoparathyroidism (low levels of the parathyroid hormone), and hypocalcemia due to rapid growth or pregnancy. It is also used for the treatment of hypocalcemia 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 hypocalcemia during exchange transfusions. Treatment of hypocalcemia should only be done under supervision of a qualified healthcare professional.
Hypocalcemic tetany (Grade: A)
Tetany is a condition of prolonged and painful spasms of the voluntary muscles, especially the fingers and toes (carpopedal spasm) as well as the facial musculature. Hypocalcemic tetany may be brought about by a calcium deficiency. Intravenous calcium has been used to treat hypocalcemia.
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.
Renal failure (Grade: A)
Kidney disease occurs when the kidneys permanently lose the ability to remove waste and maintain fluid and chemical imbalances in the body. Kidney disease may develop rapidly (over two to three months) or very slowly (over 30 to 40 years). The effectiveness of calcium salts vs. sevelamer in peritoneal dialysis has been reviewed. According to secondary sources, calcium carbonate or calcium acetate is equally effective as a phosphate binder for renal failure. Calcium citrate, however, increases absorption of aluminum, and is therefore not suggested for renal failure treatment.
Toxicity (magnesium) (Grade: A)
Intravenous calcium is used in the treatment of hypermagnesemia (high levels of magnesium in the blood). Case studies suggest intravenous calcium may 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.
Fractures (prevention) (Grade: B)
A fracture is a break in a bone or cartilage, often but not always the result of trauma. Calcium supplementation may be effective in preventing fractures through the prevention of bone loss. Further studies are needed to validate these results.
Gastrointestinal tract and colorectal cancer prevention (Grade: B)
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.
High blood potassium level (Grade: B)
Calcium supplementation 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 may 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.
Lead toxicity (Grade: B)
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.
Preeclampsia (Grade: B)
For the general population, meeting current suggestions 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. However, studies have failed to demonstrate an effect of calcium supplementation on the development of preeclampsia. Treatment of PIH should only be done under supervision of a qualified healthcare professional.
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.
Seizures (Grade: B)
Seizures are caused by uncontrolled electrical activity in the brain, which may produce a physical convulsion, minor physical signs, thought disturbances, or a combination of symptoms. According to case reports, nutritional deficiencies, including low levels of calcium may lead to changes in the electrical patterns of the brain and may increase the risk of seizures. Correcting calcium to normal levels in cases of hypocalcemia may be necessary. Further study is warranted.
Arrhythmia (Grade: C)
An arrhythmia is an abnormal heart rhythm. The heart rhythm may be too fast (tachycardia), too slow (bradycardia), or irregular. Some arrhythmias, such as ventricular fibrillation, may lead to cardiac arrest if not treated promptly. According to anecdote and animal data, intravenous calcium has been suggested as a treatment for arrhythmias. Anecdote suggests, however, that in persons with heart diseases, injected calcium may increase the risk of irregular heartbeats. Clinical trials are warranted.
Bone diseases (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 supplementation is used as an adjuvant in the treatment of rickets and osteomalacia, as well as a single therapeutic agent in nonvitamin 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.
Bone loss (steroid-induced, prevention) (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.
Breast cancer prevention (Grade: C)
Some studies have linked higher calcium and vitamin D intake with lower breast cancer risk. Further studies are needed. Treatment of breast cancer should only be done under the supervision of a qualified healthcare professional.
Cardiovascular risk reduction (Grade: C)
A review of the effects of calcium on myocardial infarction and cardiovascular events suggested a statistically nonsignificant increased risk for stroke, and a statistically significant increased risk for myocardial infarction with calcium use. Other researchers, however, have pointed out multiple flaws with this review and that more evidence is needed. A prospective analysis of the effects of calcium supplementation in postmenopausal women in Finland appeared to increase the risk of coronary heart disease (CHD). A pooled analysis of cohort studies suggested a lack of increased risk of stroke with consumption of milk products.
Childbirth (preterm birth prevention) (Grade: C)
Preterm birth is defined as a delivery that occurs prior to 37 completed weeks. It is a chief cause of perinatal mortality and morbidity around the world. Calcium supplementation has been suggested as a means of prevention of preterm birth.
Circulation (Grade: C)
Circulation is defined as the course of the blood from the heart through the arteries, capillaries, and veins back again to the heart. Normalization of priming solution ionized calcium concentration improved the hemodynamic stability of neonates receiving venovenous extracorporeal membrane oxygenation (ECMO). Further study is needed in order to draw a firm conclusion.
Cystic fibrosis (Grade: C)
Cystic fibrosis (CF) is a genetic disease characterized by the production of abnormal secretions, leading to the accumulation of mucus in the lungs, pancreas, and intestine. This build-up of mucus causes difficulty breathing and recurrent lung infections, as well as problems with nutrient absorption due to problems in the pancreas and intestines. Without treatment, CF results in death for 95% of affected children before age five; however, the longest-lived CF patient survived into his late 30s. Human studies have been conducted examining the role of calcium and vitamin D supplementation in subjects with CF. Further study is needed before a firm conclusion may be made.
Endometrial cancer prevention (Grade: C)
According to a meta-analysis of epidemiological evidence, a statistically nonsignificant, inverse association between endometrial cancer and calcium intake has been noted. Further study is needed in order to draw a more firm conclusion about the utility of calcium in decreasing endometrial cancer risk.
Fall prevention (Grade: C)
The utility of calcium in the prevention of falls, particularly in elderly populations, has been examined. Frequently calcium is used in combination with vitamin D. Further studies may be warranted.
Growth (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. One study has looked at the effects of milk supplementation in young girls with low dietary calcium intake and found that after two years, increases in bone density could be observed mainly in the legs. More studies are needed before a conclusion may be made.
Hyperparathyroidism (Grade: C)
In patients on hemodialysis, calcium supplementation may reduce secondary hyperparathyroidism (high blood levels 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.
Mortality (Grade: C)
The effects of calcium on mortality have been studied in various populations, including perinatal populations. The effects of vitamin D and calcium have also been studied. Although the effects of calcium on maternal mortality seem to be promising, further study is needed before a firm conclusion may be drawn.
Muscle strength (Grade: C)
The effects of calcium on muscle strength are unclear. The available evidence is derived from combination studies; the effect of calcium alone is unclear. Further study is needed before a firm conclusion may be drawn.
Myocardial infarction (Grade: C)
The evidence for the effects of calcium on myocardial infarction is mixed. One review of the effects of calcium on myocardial infarction and cardiovascular events suggested a statistically significant increased risk for myocardial infarction with calcium use. Other researchers, however, have pointed out multiple flaws with this review, and that more evidence is needed.
Oral mucositis (Grade: C)
Calcium phosphate has been used in the treatment and prevention of oral mucositis. Further study is needed.
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 is used as an adjuvant in the treatment of rickets and osteomalacia. Research continues into the importance of calcium alone in the treatment and prevention of rickets and osteomalacia. Treatment of rickets and osteomalacia should only be carried out under the supervision of a qualified healthcare professional.
Ovarian cancer prevention (Grade: C)
A meta-analysis of case-control studies examining the effects of dairy products and calcium on ovarian cancer risk found a lack of increased risk with dairy consumption. The analysis, however, did observe an increased risk for ovarian cancer with a lactose intake equal to three or more daily servings of milk. A nested case-control study found a statistically significant, inverse relationship between ovarian cancer risk and calcium intake. Further study is needed before a firm conclusion may be drawn.
Postpartum depression (Grade: C)
Calcium has been suggested as a treatment for postnatal depression (PND) in humans. Further data, however, are lacking. Future research for PND prevention is warranted.
Post-surgical side effects (rectal epithelial hyperproliferation) (Grade: C)
Following intestinal bypass surgery, fecal bile acids and fatty acids tend to increase, which may contribute to proliferative effects. In humans, calcium inhibited the proliferative effects, and reversed postsurgical proliferative changes. Further studies are needed in order to make a firm conclusion.
Type 2 diabetes (Grade: C)
In clinical study, combining vitamin D with calcium demonstrated a reduced risk of type 2 diabetes, with the highest intake resulting in a 33% decreased risk. For interventional trials, in hypertensive nondiabetics, compared to placebo, 1,500 milligrams daily of calcium for eight weeks improved insulin sensitivity. While promising, further trials are warranted.
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.
Cardiopulmonary resuscitation (CPR) (Grade: D)
Cardiopulmonary resuscitation is the restoration of cardiac output and pulmonary ventilation following cardiac arrest and apnea, using artificial respiration and manual closed-chest compression or open-chest cardiac massage. Per the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science, routine administration of calcium for the treatment of cardiac arrest is no longer advised. Variable results have been observed in trials, and a beneficial effect on survival is lacking with the use of calcium.
Vaginal disorders (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.