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Calcium

Other Name(s):

Acétate de Calcium, Aspartate de Calcium, Bone Meal, Calcio, Calcium Acetate, Calcium Aspartate, Calcium Carbonate, Calcium Chelate, Calcium Chloride, Calcium Citrate, Calcium Citrate Malate, Calcium D-Gluconate, Calcium Disuccinate, Calcium Gluconate, Calcium Glycerophosphate, Calcium Hydrogen Phosphate, Calcium Hydroxyapatite, Calcium Lactate, Calcium Lactogluconate, Calcium Orotate, Calcium Phosphate, Calcium Sulfate, Carbonate de Calcium, Chélate de Calcium, Chlorure de Calcium, Citrate de Calcium, Citrate Malate de Calcium, Coquilles d'Huîtres Moulues, Coquilles d'œuf, Dicalcium Phosphate, Di-Calcium Phosphate, Dolomite, Egg Shell Calcium, Gluconate de Calcium, Glycérophosphate de Calcium, Heated Oyster Shell-Seaweed Calcium, Hydroxyapatite, Lactate de Calcium, Lactogluconate de Calcium, MCHA, MCHC, Microcrystalline Hydroxyapatite, Orotate de Calcium, Ossein Hydroxyapatite, Oyster Shell, Oyster Shell Calcium, Phosphate de Calcium, Phosphate de Calcium Hydrogène, Phosphate de di-Calcium, Phosphate Tricalcium, Poudre d'os, Sulfate de Calcium, Tricalcium Phosphate.

Overview

Calcium is a mineral that is an essential part of bones and teeth. The heart, nerves, and blood-clotting systems also need calcium to work.

Calcium is taken by mouth for treatment and prevention of low calcium levels and resulting bone conditions including muscle cramps (latent tetany), osteoporosis (weak bones due to low bone density), rickets (a condition in children involving softening of the bones), and osteomalacia (a softening of bones involving pain). Calcium is also taken by mouth to prevent falls and to prevent high levels of the parathyroid hormone (hyperparathyroidism). It is also taken by mouth for premenstrual syndrome (PMS), leg cramps and depression in pregnancy, high blood pressure in pregnancy (pre-eclampsia), and to improve bone development in the baby. Calcium is used to reduce the risk of cancer, stroke, and cardiovascular disease, to increase survival following a heart attack, to help retain teeth in the elderly, and to help with weight loss.

Some people take calcium by mouth to prevent diarrhea and seizures due to sudden decreases in calcium levels. It is also taken by mouth to prevent for complications after intestinal bypass surgery, high blood pressure, high cholesterol, diabetes, metabolic syndrome, Lyme disease, to reduce high fluoride levels in children, and to reduce high lead levels. Calcium is used to prevent vitamin B12 deficiency associated with the medication metformin. It is also used to increase survival in people who have had a heart attack.

Calcium carbonate is taken by mouth as an antacid for "heartburn." Calcium carbonate and calcium acetate are also taken by mouth to reduce phosphate levels in people with kidney disease.

Calcium is used as a mouth rinse to prevent and reduce pain and swelling inside of the mouth following chemotherapy. Calcium is given intravenously (by IV) for very low calcium levels of the blood and related symptoms. It is also used for high potassium levels in the blood, muscle cramps following spider bites, and during CPR (cardiopulmonary resuscitation). Calcium gluconate and gluceptate may be injected as a shot if calcium cannot be given by IV. Calcium-rich foods include milk and dairy products, kale and broccoli, as well as the calcium-enriched citrus juices, mineral water, canned fish with bones, and soy products processed with calcium.

Calcium can interact with many prescription medications, but sometimes the effects can be minimized by taking calcium at a different time. See the section titled "Are there any interactions with medications?"

How does it work?

The bones and teeth contain over 99% of the calcium in the human body. Calcium is also found in the blood, muscles, and other tissue. Calcium in the bones can be used as a reserve that can be released into the body as needed. The concentration of calcium in the body tends to decline as we age because it is released from the body through sweat, skin cells, and waste. In addition, as women age, absorption of calcium tends to decline due to reduced estrogen levels. Calcium absorption can vary depending on race, gender, and age.

Bones are always breaking down and rebuilding, and calcium is needed for this process. Taking extra calcium helps the bones rebuild properly and stay strong.

Uses & Effectiveness

Effective for...

  • Indigestion. Taking calcium carbonate by mouth as an antacid is effective for treating indigestion.
  • High levels of potassium in the blood (hyperkalemia). Giving calcium gluconate intravenously (by IV) can reverse heart problems caused by hyperkalemia, a condition in which there is too much potassium in the blood.
  • Low levels of calcium in the blood (hypocalcemia). Taking calcium by mouth is effective for treating and preventing hypocalcemia. Also, giving calcium intravenously (by IV) is effective for treating very low levels of calcium.
  • Kidney failure. Taking calcium carbonate or calcium acetate by mouth is effective for controlling high phosphate levels in the blood in people with kidney failure. Calcium citrate is not effective for treating this condition.

Likely Effective for...

  • Weakened bones (osteoporosis) caused by corticosteroid drugs. Taking calcium along with vitamin D seems to reduce the loss of bone mineral in people using corticosteroid drugs long-term.
  • Parathyroid gland disorder (hyperparathyroidism). Taking calcium by mouth reduces parathyroid hormone levels in people with kidney failure and parathyroid hormone levels that are too high.
  • Osteoporosis. Taking calcium by mouth is effective for preventing and treating bone loss and osteoporosis. Most bone growth occurs in the teenage years, and then bone strength in women remains about the same until age 30-40. After age 40, bone loss typically occurs at rates of 0.5% to 1% per year. In men, this bone loss occurs several decades later. There is more bone loss if less than the recommended amount of calcium is obtained from the diet. This is very common among Americans. Bone loss in women over 40 can be reduced by taking calcium supplements. Some researchers estimate that taking calcium for 30 years after menopause might result in a 10% improvement in bone strength and a 50% overall reduction in the rate of bone break.
  • Reducing symptoms of premenstrual syndrome (PMS). There seems to be a link between low dietary calcium intake and symptoms of PMS. Consuming calcium daily seems to significantly reduce mood swings, bloating, food cravings, and pain. Also, increasing the amount of calcium in one's diet seems to prevent PMS. Women consuming an average of 1283 mg/day of calcium from foods seem to have about a 30% lower risk of developing PMS than women who consume an average of 529 mg/day of calcium. Taking calcium supplements, however, does not seem to prevent PMS.

Possibly Effective for...

  • Colorectal cancer. Research suggests that high intake of dietary or supplemental calcium reduces the risk of colorectal cancer. However, some conflicting evidence exists. This may be due to differences in blood levels of vitamin D. People with low levels of vitamin D do not seem to benefit from calcium supplements.
  • Increasing bone strength in fetuses. In pregnant women who eat a low amount of calcium as part of their diet, calcium supplementation increases the bone mineral density of the fetus. However, this does not appear to be beneficial for women with normal calcium levels.
  • Fluoride poisoning. Taking calcium by mouth, together with vitamin C and vitamin D supplements, seems to reduce fluoride levels in children and improve symptoms of fluoride poisoning.
  • High cholesterol. Taking calcium supplements along with a low-fat or low-calorie diet seems to modestly reduce cholesterol. Taking calcium alone, without the restricted diet, does not seem to lower cholesterol.
  • High blood pressure. Taking calcium supplements seems to reduce blood pressure slightly (usually around 1-2 mmHg) in people with or without high blood pressure. Calcium seems to work best in salt-sensitive people and people who normally get very little calcium. Taking calcium by mouth also seems to be helpful for reducing blood pressure in people with serious kidney disease.
  • High blood pressure during pregnancy (pre-eclampsia). Taking 1-2 grams of calcium by mouth daily seems to reduce pregnancy-related high blood pressure. Calcium appears to reduce the risk of high blood pressure in pregnancy by about 50%. Calcium appears to have the greatest effect in high-risk women and women with low calcium levels.
  • Tooth loss. Taking calcium and vitamin D by mouth appears to help prevent tooth loss in older people.
  • Weight loss. Adults and children with low calcium intake are more likely to gain weight, have a higher body mass index (BMI), and be overweight or obese compared to people with high calcium intake. Researchers have studied whether increasing calcium intake might help with weight loss. Some clinical research shows that increasing calcium consumption from dairy products, such as yogurt, increases weight loss, lean body mass, and body fat loss in people on a low-calorie diet as well as people on a regular unrestricted-calorie diet. Also, taking calcium supplements along with vitamin D seems to increase weight loss in people who have inadequate intake of calcium. Calcium supplements don't seem to increase weight loss in people with adequate calcium intake. Also, calcium does not appear to increase weight loss in people who are not overweight.

Possibly Ineffective for...

  • Breast cancer. Some research suggests that women who eat more calcium have a reduced risk for developing breast cancer. However, other research suggests that blood levels of calcium are not linked with breast cancer risk. Overall, most research suggests that taking calcium does not reduce the risk for breast cancer.
  • Heart disease. Most research shows that there is no association between calcium supplementation and the risk of heart disease in healthy people.
  • Heart attack. Early research suggests that people who consume more calcium in their diet have a lower risk of having a heart attack. However, the effects of calcium SUPPLEMENTS on heart attack risk are not clear. Some research suggests that calcium supplements increase heart attack risk. Other research shows there is no effect. It may be that some people have an increased risk while others do not. For example, people who take calcium as a single supplement might have an increased risk. On the other hand, people who take calcium with vitamin D do not seem to have an increased risk. Also, people who take a calcium supplement and consume more than 805 mg/day of calcium as part of their diet might be at an increased risk, while people who take a supplement and consume less calcium in their diet might not.

Insufficient Evidence to Rate Effectiveness for...

  • Cancer. Research shows that taking calcium alone does not reduce the risk of cancer. Taking calcium along with vitamin D might reduce the risk of cancer in some people, but results are conflicting. Some research shows that taking 1400-1500 mg of calcium daily plus 1100 IU of vitamin D3 (cholecalciferol) daily lowers the risk of developing cancer by 60% in healthy older women who have low blood levels of vitamin D before treatment. But other research shows that taking 1500 mg of calcium daily plus 2000 IU of vitamin D3 (cholecalciferol) daily does not reduce the risk of developing cancer in healthy older women who have adequate levels of vitamin D before treatment.
  • Diabetes. Some early research suggests that consuming more calcium from the diet or from supplements, either alone or in combination with vitamin D, lowers the risk of developing type 2 diabetes.
  • High levels of lead in the blood. Some research suggests that taking calcium supplements does not lower the levels of lead in the blood. However, other research suggests that taking calcium reduces blood lead levels by 11%.
  • Endometrial cancer. Taking calcium supplements might reduce the risk of developing endometrial cancer. However, dietary calcium does not seem to have any benefit.
  • Preventing falls. Evidence suggests that calcium plus vitamin D might help prevent falls by decreasing body sway and helping to keep blood pressure normal. Calcium alone does not seem to have the effect. Interestingly, calcium plus vitamin D seems to prevent falls in women, but not in men.
  • Stroke. There is some evidence that increasing calcium intake in the diet might decrease the risk of stroke. Other evidence suggests that increasing calcium intake does not reduce the risk of stroke.
  • Metabolic syndrome. Some evidence suggests that consuming more calcium from the diet and supplements, either alone or in combination with vitamin D, lowers the risk of developing metabolic syndrome.
  • Vitamin B12 deficiency caused by the drug metformin. Taking calcium supplements might reduce vitamin B12 deficiency caused by the diabetes drug metformin.
  • Ulcers in the lining of the mouth. Evidence suggests that using a mouth rinse containing calcium phosphate (Caphosol, EUSA Pharma) in combination with fluoride treatments reduces the duration of pain in people with mouth ulcers due to stem cell transplants.
  • Ovarian cancer. Early evidence suggests that high blood levels of calcium are linked to a reduced risk of ovarian cancer. However, other early research suggests that dietary calcium intake is not linked with the risk of ovarian cancer.
  • Depression after pregnancy (postpartum depression). Early research suggests that taking calcium daily, beginning 11-21 weeks into pregnancy, reduces depression at 12 but not 6 weeks after delivery.
  • Pregnancy-related leg cramps. Early research shows that calcium can help prevent leg cramps in the second half of pregnancy.
  • Prostate cancer. Research about how calcium affects the risk of prostate cancer has shown conflicting results. Some research suggests that taking calcium supplements daily decreases the risk of prostate cancer. However, other research suggests that there is not a link between calcium intake and the risk for developing prostate cancer.
  • Seizures. Early research suggests that calcium might help control seizures resulting from sudden drops in blood levels of calcium.
  • Lyme disease.
  • Other conditions.
More evidence is needed to rate the effectiveness of calcium for these uses.

Ineffective for...

  • Cardiac arrest. Evidence suggests that administering calcium during cardiac arrest does not increase survival and might actually worsen the chance for resuscitation.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Side Effects

Calcium is LIKELY SAFE for most people when taken by mouth or when given intravenously (by IV) and appropriately. Calcium can cause some minor side effects such as belching or gas.

Calcium is POSSIBLY UNSAFE for both adults and children when taken by mouth in high doses. Avoid taking too much calcium. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium based on age as follows: Age 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg; 19-50 years, 2500 mg; 51+ years, 2000 mg. Higher doses increase the chance of having serious side effects, such as blood levels of calcium that are too high and milk-alkali syndrome, a condition that can lead to renal stones, kidney failure and death. There is also concern that supplemental calcium can increase the risk of heart attack. Some research shows that taking calcium, often in amounts over the recommended daily intake level of 1000-1300 mg per day, is linked with an increased risk of heart attack in older people. But other research suggests there is no connection between calcium supplementation and heart attack risk. It may be that some groups have an increased risk while others do not. Continue consuming adequate amounts of calcium to meet daily requirements, but avoid excessive amounts of calcium. Be sure to consider total calcium intake from both dietary and supplemental sources and try not to exceed 1000-1200 mg of calcium per day. To figure out dietary calcium, count 300 mg/day from non-dairy foods plus 300 mg/cup of milk or fortified orange juice. Also, if calcium supplements need to be taken along with dietary calcium, consider taking ones that provide calcium along with vitamin D.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Calcium is LIKELY SAFE when taken by mouth in recommended amounts during pregnancy and breast-feeding. There is not enough information available on the safety of using calcium intravenously (by IV) during pregnancy and breastfeeding.

Low acid levels in the stomach (achlorhydria). People with low levels of gastric acid absorb less calcium if calcium is taken on an empty stomach. However, low acid levels in the stomach do not appear to reduce calcium absorption if calcium is taken with food. Advise people with achlorhydria to take calcium supplements with meals.

High levels of phosphate in the blood (hyperphosphatemia) or low levels of phosphate in the blood (hypophosphatemia): Calcium and phosphate have to be in balance in the body. Taking too much calcium can throw this balance off and cause harm. Don't take extra calcium without your health provider's supervision.

Under-active thyroid (hypothyroidism): Calcium can interfere with thyroid hormone replacement treatment. Separate calcium and thyroid medications by at least 4 hours.

Too much calcium in the blood (as in parathyroid gland disorders and sarcoidosis): Calcium should be avoided if you have one of these conditions.

Poor kidney function: Calcium supplementation can increase the risk of having too much calcium in the blood in people with poor kidney function.

Smoking: People who smoke absorb less calcium from the stomach.

Stroke: Early research suggests that older women who have had a stroke, taking calcium supplements for 5 or more years might increase the chance of developing dementia. More research is needed to determine if calcium supplements should be avoided for those who have had a stroke.

Interactions

Ceftriaxone (Rocephin)Interaction Rating: Major Do not take this combination.

Administering intravenous ceftriaxone (Rocephin) and calcium can result in life-threatening damage to the lungs and kidneys. Calcium should not be administered intravenously within 48 hours of intravenous ceftriaxone (Rocephin).

Dolutegravir (Tivicay)Interaction Rating: Major Do not take this combination.

Dolutegravir (Tivicay) is a drug used to treat HIV. Taking calcium along with dolutegravir (Tivicay) can reduce blood levels of dolutegravir (Tivicay). Theoretically, this might decrease the effects of dolutegravir (Tivicay). To avoid this interaction, dolutegravir (Tivicay) should be taken 2 hours before or 6 hours after taking calcium.

Elvitegravir (Vitekta)Interaction Rating: Major Do not take this combination.

Elvitegravir (Vitekta) is a drug used to treat HIV. Taking calcium along with elvitegravir (Vitekta) can reduce blood levels of elvitegravir (Vitekta). Theoretically, this might decrease the effects of elvitegravir (Vitekta). To avoid this interaction, elvitegravir (Vitekta) should be taken 2 hours before or 2 hours after taking calcium.

Aluminum saltsInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Calcium citrate can increase how much aluminum your body absorbs when taken with aluminum hydroxide. This increase in aluminum levels might become toxic in people with kidney disease. However, not all forms of calcium cause this effect. Calcium acetate does not appear to increase aluminum absorption.

Antibiotics (Quinolone antibiotics)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Calcium might decrease how much antibiotic your body absorbs. Taking calcium along with some antibiotics known as "quinolones" might decrease their effectiveness. To avoid this interaction, take these drugs at least 2 hours before, or 4 to 6 hours after calcium supplements.

Some quinolone antibiotics that might interact with calcium include ciprofloxacin (Cipro), levofloxacin (Levaquin), ofloxacin (Floxin), moxifloxacin (Avelox), gatifloxacin (Tequin), gemifloxacin (Factive), and others.

Antibiotics (Tetracycline antibiotics)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

In the stomach, calcium can bind to some antibiotics called tetracyclines. This decreases the amount of tetracyclines that can be absorbed. Taking calcium with tetracyclines might decrease the effectiveness of tetracyclines. To avoid this interaction, take calcium at least 2 hours before or 4 to 6 hours after taking tetracyclines.

Some tetracyclines include demeclocycline (Declomycin), minocycline (Minocin), and tetracycline (Achromycin, and others).

BisphosphonatesInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Calcium can decrease how much bisphosphate your body absorbs. Taking calcium along with bisphosphates can decrease the effectiveness of bisphosphate. To avoid this interaction, take bisphosphonate at least 30 minutes before calcium or, preferably, at a different time of day.

Some bisphosphonates include alendronate (Fosamax), etidronate (Didronel), ibandronate (Boniva), risedronate (Actonel), tiludronate (Skelid), and others.

Calcipotriene (Dovonex)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Calcipotriene (Dovonex) is a drug that is similar to vitamin D. Vitamin D helps your body absorb calcium. Taking calcium supplements along with calcipotriene (Dovonex) might cause the body to have too much calcium.

Digoxin (Lanoxin)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Calcium can affect your heart. Digoxin (Lanoxin) is used to help your heart beat stronger. Taking calcium along with digoxin (Lanoxin) might increase the effects of digoxin (Lanoxin) and lead to an irregular heartbeat. If you are taking digoxin (Lanoxin), talk to your doctor before taking calcium supplements.

Diltiazem (Cardizem, Dilacor, Tiazac)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Calcium can affect your heart. Diltiazem (Cardizem, Dilacor, Tiazac) can also affect your heart. Taking large amounts of calcium along with diltiazem (Cardizem, Dilacor, Tiazac) might decrease the effectiveness of diltiazem (Cardizem, Dilacor, Tiazac).

LevothyroxineInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Levothyroxine is used for low thyroid function. Calcium can decrease how much levothyroxine your body absorbs. Taking calcium along with levothyroxine might decrease the effectiveness of levothyroxine. Levothyroxine and calcium should be taken at least 4 hours apart.

Some brands that contain levothyroxine include Armour Thyroid, Eltroxin, Estre, Euthyrox, Levo-T, Levothroid, Levoxyl, Synthroid, Unithroid, and others.

LithiumInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Long-term lithium use can increase calcium levels in the blood. Taking lithium with calcium supplements might increase this risk of calcium levels becoming too high.

Raltegravir (Isentress)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Raltegravir (Isentress) is a drug used to treat HIV. Taking calcium along with raltegravir (Isentress) for several months might reduce blood levels of raltegravir (Isentress) and decrease its effects. Taking a single dose of calcium along with raltegravir (Isentress) does not appear to affect blood levels of raltegravir (Isentress).

Sotalol (Betapace)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Taking calcium with sotalol (Betapace) can decrease how much sotalol (Betapace) your body absorbs. Taking calcium along with sotalol (Betapace) might decrease the effectiveness of sotalol (Betapace). To avoid this interaction, take calcium at least 2 hours before or 4 hours after taking sotalol (Betapace).

Verapamil (Calan, Covera, Isoptin, Verelan)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Calcium can affect your heart. Verapamil (Calan, Covera, Isoptin, Verelan) can also affect your heart. Do not take large amounts of calcium if you are taking verapamil (Calan, Covera, Isoptin, Verelan).

Water pills (Thiazide diuretics)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Some "water pills" increase the amount of calcium in your body. Taking large amounts of calcium with some "water pills" might cause there to be too much calcium in the body. This could cause serious side effects, including kidney problems.

Some of these "water pills" include chlorothiazide (Diuril), hydrochlorothiazide (HydroDIURIL, Esidrix), indapamide (Lozol), metolazone (Zaroxolyn), and chlorthalidone (Hygroton).

EstrogensInteraction Rating: Minor Be cautious with this combination.Talk with your health provider.

Estrogen helps your body absorb calcium. Taking estrogen pills along with large amounts of calcium might increase calcium in the body too much.

Medications for high blood pressure (Calcium channel blockers)Interaction Rating: Minor Be cautious with this combination.Talk with your health provider.

Calcium channel blockers are a type of medicine used for high blood pressure. Calcium may decrease the effects of calcium channel blockers when given by IV. However, there is no evidence that taking calcium supplements or consuming foods containing calcium affects calcium channel blockers.

Some medications for high blood pressure include nifedipine (Adalat, Procardia), verapamil (Calan, Isoptin, Verelan), diltiazem (Cardizem), isradipine (DynaCirc), felodipine (Plendil), amlodipine (Norvasc), and others.

Dosing

The following doses have been studied in scientific research:

BY MOUTH:

  • For preventing low calcium levels: 1-2 grams elemental calcium daily is typically used. Sometimes it is taken with 800 IU of vitamin D.
  • For heartburn: 0.5-1.5 grams of calcium carbonate is used as needed.
  • To reduce phosphates in adults with chronic renal failure: 1-6.5 grams per day of calcium carbonate or calcium acetate has been used. The daily dose is divided up and taken between meals.
  • For preventing weak bones (osteoporosis) caused by corticosteroid use: Divided daily doses of 0.5-1 gram of elemental calcium daily.
  • For reducing parathyroid hormone levels (hyperparathyroidism): 1.2-4 grams of calcium, usually as a carbonate salt. Often it is used in combination with a low-phosphate diet or 800 IU of vitamin D.
  • For prevention of weak bones (osteoporosis): Most experts recommend taking 1000-1200 mg of calcium daily to prevent osteoporosis and broken bones.
  • For increasing fetal bone density in pregnant women with low dietary calcium intake: 300-2000 mg/day, taken during the second and third trimesters.
  • For premenstrual syndrome (PMS): 1-1.3 grams per day as calcium carbonate.
  • For preventing colorectal cancer and recurrent colorectal benign tumors (adenomas): Up to 2 grams/day.
  • For high cholesterol: 1200 mg daily, alone or in combination with vitamin D, has been used in conjunction with a low-fat or calorie-restricted diet.
  • For preventing high blood pressure during pregnancy (pre-eclampsia): 1-2 grams elemental calcium daily as calcium carbonate.
  • For preventing colorectal cancer and recurrent colorectal benign tumors (adenomas): Calcium 1200-1600 mg/day.
  • For high cholesterol: 1200 mg daily with or without vitamin D 400 IU daily has been used in conjunction with a low-fat or calorie-restricted diet.
  • For high blood pressure: Up to 0.4-2 grams daily for up to 4 years.
  • For preventing high blood pressure during pregnancy (pre-eclampsia): 1-2 grams elemental calcium daily as calcium carbonate.
  • For preventing tooth loss in elderly people: 500 mg of calcium along with 700 IU of vitamin D daily for 3 years.
  • For weight loss: Calcium 800-1200 mg/day usually in combination with a calorie-restricted diet has been used. In some cases calcium is taken in combination with 400 IU of vitamin D.
INTRAVENOUS (BY IV):
  • For low calcium levels in the blood: 100-200 mg of calcium is given as a bolus dose.
  • For high potassium levels in the blood: 20 mL of 10% calcium gluconate is administered over 5-10 minutes in most adults. In adults taking digoxin, the dose is administered over 20-30 minutes.
CHILDREN

BY MOUTH:

  • For preventing fluoride poisoning: Calcium 125 mg twice daily, in combination with ascorbic acid and vitamin D.
  • High blood pressure: 1.5 grams per day for 8 weeks has been used in adolescents.
INTRAVENOUS:
  • For high potassium levels in the blood: 0.5 mL of 10% calcium gluconate is administered over 5-10 minutes.
Calcium carbonate and calcium citrate are the two most commonly used forms of calcium.

Calcium supplements are usually divided into two doses daily in order to increase absorption. It's best to take calcium with food in doses of 500 mg or less.

The Institute of Medicine publishes a recommended daily allowance (RDA) for calcium which is an estimate of the intake level necessary to meet the requirements of nearly all healthy individuals in the population. The current RDA was set in 2010. The RDA varies based on age as follows: Age 1-3 years, 700 mg; 4-8 years, 1000 mg; 9-18 years, 1300 mg; 19-50 years, 1000 mg; Men 51-70 years, 1000 mg; Women 51-70 years, 1200 mg; 70+ years, 1200 mg; Pregnant or Lactating (under 19 years), 1300 mg; Pregnant or Lactating (19-50 years), 1000 mg.

The Institute of Medicine also sets the daily tolerable upper intake level (UL) for calcium based on age as follows: Age 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-3 years, 2500 mg; 9-18 years, 3000 mg; 19-50 years, 2500 mg; 51+ years, 2000 mg. Doses above these levels should be avoided.

Doses over the recommended daily intake level of 1000-1300 mg/day for most adults have been associated with an increased risk of heart attack. Until more is known, continue consuming adequate amounts of calcium to meet daily requirements, but not excessive amounts of calcium. Be sure to consider total calcium intake from both dietary and supplemental sources and try not to exceed 1000-1300 mg of calcium per day. To figure out dietary calcium, count 300 mg/day from non-dairy foods plus 300 mg/cup of milk or fortified orange juice.