Author: Yvette C. Terrie, BSPharm, RPh
Pharmacists can help their patients determine the best way to meet their daily calcium requirements.
Calcium is best obtained through dietary sources, but many people—especially women—do not consume enough through dietary means alone and choose to use calcium supplements.
The FDA has approved calcium supplements for the treatment and prevention of calcium deficiency, which can lead to an increased risk of rickets, osteomalacia, or osteoporosis.1-3
Calcium supplements are also approved for treating acid indigestion as well as hyperphosphatemia, which is associated with end-stage renal disease.2
Studies have demonstrated that calcium supplements may also be beneficial in alleviating or preventing premenstrual syndrome (PMS) in some female patients, but patients should consult with their primary health care provider before using the supplements for this purpose.2
Some clinical studies have suggested that calcium may help reduce cardiovascular disease (CVD) risk. However, data have been inconsistent and conflicting, and more research is needed.1
In addition, several clinical trials have reported a correlation between increased calcium intake and reduced blood pressure and risk of hypertension, and some studies have linked higher calcium intake to weight loss over time.1
Calcium carbonate and calcium citrate are the 2 most common forms of calcium found in supplements.1
(Calcium carbonate supplements contain 40% elemental calcium, while calcium citrate contains 21% elemental calcium.1
) Other forms of calcium supplements include calcium lactate, calcium gluconate, and calcium phosphate.2
Calcium supplements are available as single-entity products or in combination with vitamin D in various dosage forms including tablets, caplets, chewable tablets, and gummies. Calcium is also found in multivitamin/multimineral supplements. Approximately 43% of the US population, including almost 70% of older women, use dietary supplements that contain calcium.1
Factors to consider when choosing a calcium supplement include the reputation of the producer, product purity, absorbability tolerance, convenience, dose form, and cost.4
Counseling Patients About Calcium Supplements
When counseling patients about calcium supplements, pharmacists can take the opportunity to increase awareness of osteoporosis—especially in women, who are more likely to suffer from it—and make sure patients are aware of preventive measures they can take to reduce its incidence. Pharmacists can also identify patients at increased risk of bone loss or osteoporosis because they use certain medications or have certain medical conditions. Pharmacists should also be sure to educate patients regarding the potential dangers of consuming too much calcium.
Pharmacists are in a critical position to identify possible contraindications or drug interactions that may occur when certain pharmacologic agents are used in conjunction with calcium supplements and to make clinical recommendations accordingly. Total calcium intake, including dietary and supplementary calcium, should not exceed 2.5 grams a day. Exceeding this level of daily calcium intake can result in elevated calcium levels in the urine and renal stones.2
Hypercalcemia may also cause anorexia, nausea, vomiting, constipation, and polyuria, particularly in patients taking high-dose vitamin D formulations.2
Since some pharmacologic agents can inhibit or decrease calcium absorption, patients should discuss calcium supplementation with their primary health care provider to determine whether it is appropriate.2
Calcium can also interfere with the absorption of bisphosphonates, so patients should wait at least 30 minutes before taking calcium supplements after taking risedronate, alendronate, or alendronate/ cholecalciferol, and at least 60 minutes after taking ibandronate.2,9
Examples of other medications that should be administered in separate dosing intervals (at least 2 hours apart) when used in conjunction with calcium supplements include antacids containing aluminum, tetracyclines, and fluoroquinolones.2
Since calcium carbonate products are insoluble salts, supplements containing calcium carbonate should be taken with food to augment absorption.2
Calcium citrate products can be taken without regard to food.
Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia.
Dietary Supplement Fact Sheet Calcium. National Institutes of Health Office of National Diet Supplements website. http://ods.od.nih.gov/factsheets/calcium.asp. Accessed May 5, 2013.
Huckleberry Y, Rollins C. Essential and conditionally essential nutrients. In: Krinsky D, Berardi R, Ferreri S, et al, eds. Handbook of Nonprescription Drugs. 17th ed. Washington, DC: American Pharmacists Association; 2012.
Calcium dietary supplement fact sheet. NIH Office of Dietary Supplements website. http://ods.od.nih.gov/factsheets/Calcium-HealthProfessional.
Calcium and Vitamin D: What You Need to Know. The National Osteoporosis Foundation website. www.nof.org/articles/10#CALCIUMSUPPLEMENTS.
Calcium supplements may raise odds of heart death in women. Health Day website. http://consumer.healthday.com/senior-citizen-information-31/misc-death-and-dying-news-172/calcium-supplements-may-raise-odds-of-heart-death-in-women-673423.html.
Michaëlsson K, Melhus H, Warensjö Lemming E, Wolk A, Byberg L. Long term calcium intake and rates of all cause and cardiovascular mortality: community based prospective longitudinal cohort study. BMJ. 2013;346:f228.
Vitamin D and calcium supplementation to prevent fractures. US Preventive Services Task Force website. www.uspreventiveservicestaskforce.org/uspstf12/vitamind/vitdfact.pdf.
Calcium may cut risk for precancerous colon lesions in some people. Medline Plus website. www.nlm.nih.gov/medlineplus/news/fullstory_135771.html.
High calcium intake associated with reduced colorectal adenoma risk in certain individuals. American Association for Cancer Research website. www.aacr.org/home/public--media/aacr-press-releases.aspx?d=3099.
Types of osteoporosis medications. National Osteoporosis Foundation website. www.nof.org/articles/22.
Xiao Q, Murphy RA, Houston DK, Harris TB, Chow W, Park Y. Dietary and supplemental calcium intake and cardiovascular disease mortality: the National Institutes of Health–AARP Diet and Health Study. JAMA Intern Med, 2013;173(8):639-646.