Calcium for Sports & Fitness

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Why Use

Calcium

Why Do Athletes Use It?*

Some athletes say that calcium helps prevent muscle cramps and makes their bones stronger.

What Do the Advocates Say?*

Calcium is especially important for athletes because they are more likely to lose calcium, as well as other minerals, through perspiration.

In addition to being important for strong bones, calcium is required for muscle contraction. Without enough calcium you may experience muscle cramps.

*Athletes and fitness advocates may claim benefits for this supplement based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles.

Dosage & Side Effects

Calcium

How Much Is Usually Taken by Athletes?

Calcium is important for achieving and maintaining optimum bone density. Some athletes, especially women with low body weight and/or amenorrhea, are at risk for serious bone loss and fractures.1 , 2 Contributing to this risk are the diets of these athletes, which are frequently deficient in calcium.3 All athletes should try to achieve the recommended intakes of calcium, which are 1,300 mg per day for teenagers and 1,000 mg per day for adults. Other uses of calcium for sports and fitness, including prevention or relief of sports-related muscle cramps, have not been studied.

Side Effects

Constipation , bloating, and gas are sometimes reported with the use of calcium supplements.4 A very high intake of calcium from dairy products combined with large amounts of supplemental calcium carbonate (used as an antacid) 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) typically does not cause side effects. People with prostate cancer should avoid supplementing with calcium without medical supervision.

A combined analysis of 15 controlled trials found that long-term calcium supplementation was associated with a significant increase of approximately 30% in the incidence of myocardial infarctions (heart attacks).5 Since these studies were not designed to examine the effect of calcium on heart attack risk, it is possible that the findings in this post hoc (after the fact) analysis were due to chance. A more recent study found that long-term calcium supplementation did not result in an increased incidence of cardiovascular disease-related death or hospitalization.6 Moreover, a pooled analysis of randomized controlled trials found that supplementing elderly individuals with a combination of calcium and vitamin D significantly decreased the mortality rate by 7%.7

In the past, calcium supplements in the forms of bone meal (including microcrystalline hydroxyapatite [MCHC]), dolomite, and oyster shell have sometimes had higher lead levels than permitted by stringent California regulations, though generally less than the levels set by the federal government.8 “Refined” forms (which would include calcium citrate malate [CCM], calcium citrate, and most calcium carbonate) have low levels of lead.9 More recently, a survey of over-the-counter calcium supplements found low or undetectable levels of lead in most products,10 representing a sharp decline in lead content of calcium supplements since 1993. People who decide to take bone meal, dolomite, oyster shell, or coral calcium for long periods of time can contact the supplying supplement company to request independent laboratory analysis showing minimal lead levels.

Interactions with Supplements, Foods, & Other Compounds

Some studies have shown that calcium competes for absorption with a number of other minerals, while other studies have found no such competition. To be on the safe side, some doctors recommend that people taking calcium for long periods of time should also take a multimineral supplement.

One study has shown that taking calcium can interfere with the absorption of phosphorus, which, like calcium, is important for bone health.11. Although most western diets contain ample or even excessive amounts of phosphorus, older people who supplement with large amounts of calcium may be at risk of developing phosphorus deficiency. For this reason, the authors of this study recommend that, for elderly people, at least some of the supplemental calcium be taken in the form of tricalcium phosphate or some other phosphorus-containing preparation.

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.

Animal studies have shown that essential fatty acids (EFAs) increase calcium absorption from the gut, in part by enhancing the effects of vitamin D and reducing loss of calcium in the urine.12

Lysine supplementation increases the absorption of calcium and may reduce its excretion.13 As a result, some researchers believe that lysine may eventually be shown to have a role in the prevention and treatment of osteoporosis.14

Interactions with Medicines

Certain medicines interact with this supplement.

Types of interactions: Beneficial Adverse Check

Replenish Depleted Nutrients

  • Albuterol

    Therapeutic amounts of intravenous salbutamol (albuterol) in four healthy people were associated with decreased plasma levels of calcium, magnesium, phosphate, and potassium.15 Decreased potassium levels have been reported with intramuscular and subcutaneous albuterol administration.16 How frequently this effect occurs is not known; whether these changes are preventable through diet or supplementation is also unknown.

  • Aluminum Hydroxide

    Aluminum hydroxide may increase urinary and stool loss of calcium.17 Also, aluminum is a toxic mineral, and a limited amount of aluminum absorption from aluminum-containing antacids does occur.18 As a result, most doctors do not recommend routine use of aluminum-containing antacids.19 Other types of antacids containing calcium or magnesium instead of aluminum are available.

  • Beclomethasone

    Most of an inhaled dose of beclomethasone is actually swallowed, which may lead to reduced absorption of calcium.20 Health practitioners may recommend calcium supplementation to individuals using beclomethasone inhalers.

  • Budesonide

    Most of an inhaled dose of beclomethasone is actually swallowed, which may lead to reduced absorption of calcium.21 Health practitioners may recommend calcium supplementation to individuals using beclomethasone inhalers.

  • Busulfan

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.22

  • Caffeine

    In 205 healthy postmenopausal women, caffeine consumption (three cups of coffee per day) was associated with bone loss in women with calcium intake of less than 800 mg per day.23 In a group of 980 postmenopausal women, lifetime caffeine intake equal to two cups of coffee per day was associated with decreased bone density in those who did not drink at least one glass of milk daily during most of their life.24 However, in 138 healthy postmenopausal women, long-term dietary caffeine (coffee) intake was not associated with bone density.25 Until more is known, postmenopausal women should limit caffeine consumption and consume a total of approximately 1,500 mg of calcium per day (from diet and supplements).

  • Capecitabine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.27

  • Carbamazepine

    Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.28 Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.29 Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

  • Carboplatin

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.30

  • Carmustine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.31

  • Chlorambucil

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.32

  • Cholestyramine

    Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A, D, E, and K.33 , 34 Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.35 Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.36

  • Cisplatin

    Cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.37

  • Cladribine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.38

  • Colesevelam

    Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A, D, E, and K.39 , 40 Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.41 Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.42

  • Colestipol

    Bile acid sequestrants, including colestipol, may prevent absorption of folic acid and the fat-soluble vitamins A, D, E, K.43 , 44 People taking colestipol should consult with their doctor about vitamin malabsorption and supplementation. People should take other drugs and vitamin supplements one hour before or four to six hours after colestipol to improve absorption.45

    Animal studies suggest calcium and zinc may be depleted by taking cholestyramine, another bile acid sequestrant. 46 Whether these same interactions would occur with colestipol is not known.

  • Cortisone

    Oral corticosteroids reduce absorption of calcium47 and interfere with the activation and metabolism of the vitamin,48 , 49 , 50 , 51 increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.52 An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis.53 Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.

  • Cycloserine

    Cycloserine may interfere with calcium and magnesium absorption.54 The clinical significance of these interactions is unclear.

    Cycloserine may interfere with the absorption and/or activity of folic acid, vitamin B6, and vitamin B12.55 , 56 The clinical importance of this interaction is unclear.

  • Cytarabine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.57

  • Dexamethasone

    Oral corticosteroids reduce absorption of calcium65 and interfere with the activation and metabolism of the vitamin,66 , 67 , 68 , 69 increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.70 An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis.71 Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.

  • Diclofenac

    Diclofenac decreases the amount of calcium lost in the urine,72 which may help prevent bone loss in postmenopausal women.73

  • Docetaxel

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.74

  • Erythromycin

    Erythromycin may interfere with the absorption and/or activity of calcium, folic acid, magnesium, vitamin B6 and vitamin B12,75 which may cause problems, especially with long-term erythromycin treatment. Until more is known, it makes sense for people taking erythromycin for longer than two weeks to supplement with a daily multivitamin-multimineral.

  • Felbamate

    Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.83 Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.84 Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

  • Felodipine

    A study of felodipine indicated that the drug caused increased excretion of calcium.85 Whether this effect could lead to increased bone loss is unknown, but some health practitioners may recommend calcium supplementation to individuals taking felodipine. Although the effectiveness of some calcium channel blockers may be reduced with calcium supplementation,86 this effect has not been observed in people taking felodipine.

  • Floxuridine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.87

  • Fludarabine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.88

  • Flunisolide

    Most of an inhaled dose of beclomethasone is actually swallowed, which may lead to reduced absorption of calcium.89 Health practitioners may recommend calcium supplementation to individuals using beclomethasone inhalers.

  • Flurbiprofen

    Elevated calcium and vitamin D blood levels are commonly found in people with sarcoidosis. In one individual with sarcoidosis, taking flubiprofen lowered elevated blood calcium levels, but did not alter the concentration of vitamin D.90 One controlled study showed that flurbiprofen reduced blood levels of vitamin D in people with frequent calcium kidney stones.91 Further research is needed to determine whether flurbiprofen reduces blood calcium and vitamin D levels in healthy people.

  • Fluticasone

    Most of an inhaled dose of beclomethasone is actually swallowed, which may lead to reduced absorption of calcium.92 Health practitioners may recommend calcium supplementation to individuals using beclomethasone inhalers.

  • Furosemide
    Calcium depletion, in some cases severe, has been observed in some people taking loop diuretics.93 People taking loop diuretics should ask their doctor whether they should take a calcium supplement or have their blood level of calcium monitored.
  • Gabapentin

    Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.94 Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches) cramps, and spasm during the first two weeks of life.95 Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

  • Gentamicin

    Gentamicin has been associated with hypocalcemia (low calcium levels) in humans.96 In a study using rats, authors reported oral calcium supplementation reduced gentamicin-induced kidney damage.97 The implications of this report for humans are unclear. People receiving gentamicin should ask their doctor about monitoring calcium levels and calcium supplementation.

  • Hydroxychloroquine

    Normally, the active form of vitamin D increases the absorption of calcium into the body. In a 45-year-old woman with sarcoidosis, taking hydroxychloroquine blocked the formation of active vitamin D, which helped normalize elevated blood levels of calcium in this case.98 Whether hydroxychloroquine has this effect in people who don’t have sarcoidosis or elevated calcium is unknown. Until controlled research explores this interaction more thoroughly, people taking hydroxychloroquine might consider having their vitamin D and/or calcium status monitored by a health practitioner.

  • Hydroxyurea

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.99

  • Ifosfamide

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.100

  • Indomethacin

    Indomethacin has been reported to decrease absorption of folic acid and vitamin C.101 Under certain circumstances, indomethacin may interfere with the actions of vitamin C. Calcium and phosphate levels may also be reduced with indomethacin therapy.102 It remains unclear whether people taking this drug need to supplement any of these nutrients.

  • Isoniazid

    Isoniazid may interfere with the activity of other nutrients, including vitamin B3 (niacin), vitamin B12, vitamin D, and vitamin E, folic acid, calcium, and magnesium.103 , 104 Supplementation with vitamin B6 is thought to help prevent isoniazid-induced niacin deficiency; however, small amounts of vitamin B6 (e.g. 10 mg per day) appear to be inadequate in some cases. People should consider using a daily multivitamin-mineral supplement during isoniazid therapy.

  • Levalbuterol

    Most of an inhaled dose of beclomethasone is actually swallowed, which may lead to reduced absorption of calcium.105 Health practitioners may recommend calcium supplementation to individuals using beclomethasone inhalers.

  • Levetiracetam

    Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.106 Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.107 Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

  • Lomustine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.115

  • Mechlorethamine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.116

  • Melphalan

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.117

  • Mercaptopurine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.118

  • Methotrexate

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.130

  • Mineral Oil

    Mineral oil has interfered with the absorption of many nutrients, including beta-carotene, phosphorus, potassium, and vitamins A, D, K, and E in some,138 but not all,139 research. Taking mineral oil on an empty stomach may reduce this interference. It makes sense to take a daily multivitamin-mineral supplement two hours before or after mineral oil. It is important to read labels, because many multivitamins do not contain vitamin K or contain inadequate (less than 100 mcg per day) amounts.

  • Neomycin

    Neomycin can decrease absorption or increase elimination of many nutrients, including calcium, carbohydrates, beta-carotene, fats, folic acid, iron, magnesium, potassium, sodium, and vitamin A, vitamin B12, vitamin D, and vitamin K.140 , 141 Surgery preparation with oral neomycin is unlikely to lead to deficiencies. It makes sense for people taking neomycin for more than a few days to also take a multivitamin-mineral supplement.

  • Omeprazole

    In a study of elderly women, administration of omeprazole decreased the absorption of calcium,149 presumably because the drug decreased the stomach's production of hydrochloric acid, which is necessary for calcium absorption. The form of calcium used in the study to test calcium absorption was calcium carbonate. Drugs that reduce stomach acid secretion may not inhibit other forms of calcium, such as calcium citrate.150

  • Oxcarbazepine

    Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.153 Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.154 Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

  • Phenobarbital

    Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.155 Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches), cramps, and spasms that can be caused by calcium deficiency during the first two weeks of life.156 Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

  • Phenytoin

    Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.157 Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.158 Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

  • Polifeprosan 20 with Carmustine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.159

  • Prednisolone

    Oral corticosteroids reduce absorption of calcium and interfere with the activation and metabolism of the vitamin,160 , 161 , 162 , 163 , 164 increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.165 An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis.166 Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.

  • Prednisone

    Oral corticosteroids reduce absorption of calcium167 and interfere with the activation and metabolism of the vitamin,168 , 169 , 170 , 171 increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.172 An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis.173 Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.

  • Primidone

    Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.174 Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.175 Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

  • Sulfamethoxazole

    Sulfonamides, including sulfamethoxazole, can decrease absorption of calcium, magnesium, and vitamin B12.176 This is generally not a problem when taking sulfamethoxazole for two weeks or less. People taking sulfamethoxazole for longer than two weeks should ask their doctor about nutrient monitoring and supplementation.

    Note: Since sulfamethoxazole is often prescribed in combination with trimethoprim (for example, in Bactrim or Septra), it may be easy to associate this interaction with trimethoprim. However, this interaction is not known to occur with trimethoprim alone.

  • Thioguanine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.177

  • Thiotepa

    Cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.178

  • Tobramycin

    Calcium , magnesium, and potassium depletion requiring prolonged replacement were reported in a child with tetany who had just completed a three-week course of i.v. tobramycin.179 The authors suggest this may have been due to kidney damage related to the drug. Seventeen patients with cancer developed calcium, magnesium, and potassium depletion after treatment with aminoglycoside antibiotics, including tobramycin.180 The authors suggested a possible potentiating action of tobramycin-induced mineral depletion by chemotherapy drugs, especially doxorubicin (Adriamycin®).

    Until more is known, people receiving i.v. tobramycin should ask their doctor about monitoring calcium, magnesium, and potassium levels and the possibility of mineral replacement.

  • Topiramate

    Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.181 Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.182 Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

  • Triamterene

    A review of the research literature indicates that triamterene may increase calcium loss.183 The importance of this information is unclear.

  • Trimethoprim/ Sulfamethoxazole

    Sulfonamides, including sulfamethoxazole, can decrease absorption of calcium, magnesium, and vitamin B12.184 This is generally not a problem when taking sulfamethoxazole for two weeks or less. People taking sulfamethoxazole for longer than two weeks should ask their doctor about nutrient monitoring and supplementation.

  • Uracil Mustard

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.185

  • Valproate

    Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.186 Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches), cramps, and spasms that can be caused by calcium deficiency during the first two weeks of life.187 Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

  • Vinblastine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.188

  • Vincristine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.189

Reduce Side Effects

  • Metformin

    Metformin therapy has been shown to deplete vitamin B12,126 and sometimes, but not always,127 folic acid as well.128 This depletion occurs through the interruption of a calcium-dependent mechanism. Supplementation with calcium has reversed this effect in a clinical trial.129 People taking metformin should supplement vitamin B12 and folic acid or ask their doctor to monitor folic acid and vitamin B12 levels.

  • Methylprednisolone

    Oral corticosteroids reduce absorption of calcium131 and interfere with the activation and metabolism of the vitamin,132 , 133 , 134 , 135 increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.136 An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis.137 Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.

  • Oxaliplatin
    In a double-blind trial, intravenous administration of calcium and magnesium before and after administration of oxaliplatin prevented the development of oxaliplatin-induced nerve damage.151 However, in another double-blind trial, the same treatment regimen as in the other study did not prevent oxaliplatin-induced nerve damage.152 It is not known whether oral administration of these minerals would also be beneficial.

Support Medicine

  • Calcitonin

    Supplementation with 1,500 mg per day of calcium enhances the effects of nasal calcitonin on bone mass of the lumbar spine.26 Women who take a calcitonin nasal product for osteoporosis should also take calcium.

  • Ethinyl Estradiol and Norgestrel

    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.76 , 77 , 78 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.79 , 80 , 81 Oral contraceptives may interfere with manganese absorption.82 The clinical importance of these actions remains unclear.

  • Levonorgestrel

    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.108 , 109 , 110 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.111 , 112 , 113 Oral contraceptives may interfere with manganese absorption.114 The clinical importance of these actions remains unclear.

  • Mestranol and Norethindrone

    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.119 , 120 , 121 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.122 , 123 , 124 Oral contraceptives may interfere with manganese absorption.125 The clinical importance of these actions remains unclear.

  • Norgestimate-Ethinyl Estradiol

    A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.142 , 143 , 144 OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.145 , 146 , 147 OCs may interfere with manganese absorption.148 The clinical importance of these actions remains unclear.

Reduces Effectiveness

  • Ciprofloxacin

    Calcium supplements are known to interfere with the absorption of ciprofloxacin. The same interference has been shown to occur when calcium-fortified orange juice is taken at the same time as ciprofloxacin.191

  • Demeclocycline

    Taking mineral supplements or antacids that contain aluminum, calcium, iron, magnesium, or zinc at the same time as tetracyclines inhibits the absorption of the drug.192 Therefore, individuals should take tetracyclines at least two hours before or after products containing minerals.

  • Doxycycline

    Many minerals can decrease the absorption and reduce effectiveness of doxycycline, including calcium, magnesium, iron, zinc, and others.193 To avoid these interactions, doxycycline should be taken two hours before or two hours after dairy products (high in calcium) and mineral-containing antacids or supplements.

  • Gemifloxacin

    A recent study showed that taking calcium carbonate and gemifloxacin at the same time results in a significant reduction in blood levels of the drug.194 Consequently, gemifloxacin and calcium supplements should not be taken at the same time.

  • Minocycline

    Taking calcium, iron, magnesium, or zinc at the same time as minocycline can decrease the absorption of both the drug195 , 196 and the mineral. Therefore, calcium, iron, magnesium, or zinc supplements, if used, should be taken an hour before or after the drug.

  • Nadolol

    Calcium supplements, if taken at the same time as some beta-blocker drugs, may reduce blood levels of the drug.197 However, whether calcium affects nadolol in this manner is unknown. Until more information is available, people on nadolol should take calcium supplements an hour before or two hours after the drug.

  • Ofloxacin

    Minerals including calcium, iron, magnesium, and zinc can bind to fluoroquinolones, including ofloxacin, greatly reducing drug absorption.198 Ofloxacin should be taken four hours before or two hours after consuming antacids (Maalox®, Mylanta®, Tumms®, Rolaids® and others) that may contain these minerals and mineral-containing supplements.199

  • Sotalol

    One controlled study showed that taking sotalol with a calcium gluconate solution dramatically reduces the absorption of the drug.200 Consequently, people who take a calcium supplement should take sotalol an hour before or two hours after the calcium.

  • Tetracycline

    Many minerals can decrease the absorption of tetracycline, thus reducing its effectiveness. These minerals include aluminum (in antacids), calcium (in antacids, dairy products, and supplements), magnesium (in antacids and supplements), iron (in food and supplements), zinc (in food and supplements), and others.

Potential Negative Interaction

  • Calcium Acetate

    People with kidney failure may develop high blood levels of calcium while taking calcium acetate. Since calcium acetate is a source of supplemental calcium, people taking the drug should avoid taking additional calcium supplements.190 People experiencing adverse effects of high blood calcium—such as loss of appetite, mental depression, poor memory, and muscle weakness—should notify their healthcare practitioner.

  • Sucralfate
    Slight increases in blood calcium levels may occur in people taking sucralfate, which could be aggravated by calcium supplementation.201 Therefore, people taking calcium supplements and sucralfate should have their blood calcium levels monitored by their healthcare practitioner and may need to avoid calcium supplementation.

Explanation Required

  • Alendronate

    Calcium supplements may interfere with alendronate absorption.202 However, one researcher suggested that addition of large amounts of supplemental calcium to alendronate therapy in patients with bone metastases (with evidence of osteomalacia) related to prostate cancer might improve the clinical outcome.203 Moreover, both calcium and alendronate are commonly used in the treatment of osteoporosis in the same people. To prevent potential interactions, alendronate should be taken two hours before or after calcium supplements.

  • Bendroflumethiazide

    Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.204 As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

  • Chlorothiazide

    Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.205 As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

  • Chlorthalidone

    Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.206 As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

  • Desogestrel-Ethinyl Estradiol

    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.207 , 208 , 209 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.210 , 211 , 212 Oral contraceptives may interfere with manganese absorption.213 The clinical importance of these actions remains unclear.

  • Dessicated Thyroid

    Thyroid hormones have been reported to increase urinary loss of calcium.214 However, recent research suggests that, under most circumstances, taking thyroid hormones may not be associated with reduced bone density.215 , 216 Calcium supplementation for people taking long-term thyroid medication has not yet been proven to be either helpful or necessary.

    Simultaneous ingestion of some calcium formulations with levothyroxine has been reported to reduce the effectiveness of levothyroxine.217 For example, 1,200 mg per day of calcium as calcium carbonate, taken along with levothyroxine, significantly reduced absorption of the thyroid hormone.218 Levothyroxine activity will not be blocked if it is taken in the morning and calcium carbonate is taken after lunch and dinner. Separating these medications by at least four hours is recommended.

  • Ethinyl Estradiol and Levonorgestrel
    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.219 , 220 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.221 , 222 Oral contraceptives may interfere with manganese absorption.223 The clinical importance of these actions remains unclear.
  • Ethinyl Estradiol and Norethindrone

    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.224 , 225 , 226 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.227 , 228 , 229 Oral contraceptives may interfere with manganese absorption.230 The clinical importance of these actions remains unclear.

  • Ethinyl Estradiol and Norgestimate
    Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.231 , 232 , 233 Oral contraceptives may interfere with manganese absorption.234 The clinical importance of these actions remains unclear.

     

  • Etidronate

    Calcium supplements may interfere with alendronate absorption.235 However, one researcher suggested that addition of large amounts of supplemental calcium to alendronate therapy in patients with bone metastases (with evidence of osteomalacia) related to prostate cancer might improve the clinical outcome.236 Moreover, both calcium and alendronate are commonly used in the treatment of osteoporosis in the same people. To prevent potential interactions, alendronate should be taken two hours before or after calcium supplements.

  • Hydrochlorothiazide

    Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.237 As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

  • Hydroflumethiazide

    Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.238 As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

  • Indapamide

    Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.239 As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

  • Lactase

    Dairy products are rich in calcium. Lactase-deficient people may not consume milk and therefore have fewer dietary sources of calcium available to them. Lactase products allow lactase-deficient people to digest milk products, increasing their sources and intake of dietary calcium.

  • Levonorgestrel-Ethinyl Estrad

    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.240 , 241 , 242 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.243 , 244 , 245 Oral contraceptives may interfere with manganese absorption.246 The clinical importance of these actions remains unclear.

  • Levothyroxine

    Thyroid hormones have been reported to increase urinary loss of calcium.247 However, recent research suggests that, under most circumstances, taking thyroid hormones may not be associated with reduced bone density.248 , 249 Calcium supplementation for people taking long-term thyroid medication has not yet been proven to be either helpful or necessary.

    Simultaneous ingestion of some calcium formulations with levothyroxine has been reported to reduce the effectiveness of levothyroxine.250 For example, 1,200 mg per day of calcium as calcium carbonate, taken along with levothyroxine, significantly reduced absorption of the thyroid hormone.251 Calcium citrate and calcium acetate have also been shown to decrease levothyroxine absorption.252 Levothyroxine absorption will not be blocked if it is taken in the morning and calcium is taken after lunch and dinner. Separating these medications by at least four hours is recommended.

  • Liothyronine

    Thyroid hormones have been reported to increase urinary loss of calcium.253 However, recent research suggests that, under most circumstances, taking thyroid hormones may not be associated with reduced bone density.254 , 255 Calcium supplementation for people taking long-term thyroid medication has not yet been proven to be either helpful or necessary.

    Simultaneous ingestion of some calcium formulations with levothyroxine has been reported to reduce the effectiveness of levothyroxine.256 For example, 1,200 mg per day of calcium as calcium carbonate, taken along with levothyroxine, significantly reduced absorption of the thyroid hormone.257 Levothyroxine activity will not be blocked if it is taken in the morning and calcium carbonate is taken after lunch and dinner. Separating these medications by at least four hours is recommended.

  • Liotrix

    Thyroid hormones have been reported to increase urinary loss of calcium.258 However, recent research suggests that, under most circumstances, taking thyroid hormones may not be associated with reduced bone density.259 , 260 Calcium supplementation for people taking long-term thyroid medication has not yet been proven to be either helpful or necessary.

    Simultaneous ingestion of some calcium formulations with levothyroxine has been reported to reduce the effectiveness of levothyroxine.261 For example, 1,200 mg per day of calcium as calcium carbonate, taken along with levothyroxine, significantly reduced absorption of the thyroid hormone.262 Levothyroxine activity will not be blocked if it is taken in the morning and calcium carbonate is taken after lunch and dinner. Separating these medications by at least four hours is recommended.

  • Methyclothiazide

    Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.263 As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

  • Metolazone

    Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.1 As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

  • Pamidronate

    Calcium supplements may interfere with alendronate absorption.264 However, one researcher suggested that addition of large amounts of supplemental calcium to alendronate therapy in patients with bone metastases (with evidence of osteomalacia) related to prostate cancer might improve the clinical outcome.265 Moreover, both calcium and alendronate are commonly used in the treatment of osteoporosis in the same people. To prevent potential interactions, alendronate should be taken two hours before or after calcium supplements.

  • Polythiazide

    Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.266 As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

  • Risedronate

    Short-term treatment with risedronate in people with hyperparathydoidism—a disorder characterized by high blood levels of calcium—resulted in lower calcium blood levels.267 Additional research is needed to determine whether people taking risedronate for Paget’s disease might develop low blood calcium levels. As a precaution, people with Paget’s disease should take supplemental calcium and vitamin D if dietary intake is inadequate. However, taking risedronate at the same time as calcium supplements reduces absorption of the drug.268 Therefore, people taking risedronate for Paget’s disease should take calcium supplements an hour before or two hours after taking the drug.

  • Sodium Fluoride

    Research shows that calcium from leg bones may be transferred to bones in the spine causing stress fractures when fluoride is taken alone. However, supplementing with 1,500 mg of calcium each day together with slow-release forms of fluoride increases the bone density of the lumbar spine without causing fractures.269 Therefore, people taking sodium fluoride to treat osteoporosis should probably supplement with calcium to prevent this adverse effect. However, taking fluoride and calcium at the same time significantly reduces the absorption of fluoride;270 consequently, they should be taken at least an hour apart.

  • Trichlormethiazide

    Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.271 As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

More Resources

Calcium

Where to Find It

Most dietary calcium comes from dairy products. The myth that calcium from dairy products is not absorbed is not supported by scientific research.272 , 273 Other good sources include sardines, canned salmon, green leafy vegetables, and tofu.

Resources

See a list of books, periodicals, and other resources for this and related topics.