Critical Recommendations for Pharmacist Counseling About Calcium Supplements and Heart Disease
Calcium is often in news reports emphasizing that the majority of Americans don’t consume enough of the mineral to keep bones healthy. Now it’s in the headlines for another reason, with researchers warning that calcium supplements can increase the risk for cardiovascular disease. Such conflicting information leaves people baffled about whether or not they should take supplements.
Health professionals prefer to send patients to the nutrition experts like registered dietitians, but pharmacists also need to counsel about calcium supplements for two vital reasons. If you sell supplements, you’re the expert on site who must be prepared to answer questions. And, more importantly, calcium supplements can interact with some medications, so patient safety can depend on your advice.
Cardiovascular Risks from Calcium Supplements
The debate over supplemental calcium and cardiovascular disease isn’t new. At least 18 studies published between 2008 and 2014 reported conflicting results—some found that supplements increased the risk for cardiovascular disease and myocardial infarction—others didn’t.1 In October 2016, the Journal of the American Heart Association published a study based on data from the Multi-Ethnic Study of Atherosclerosis (MESA), in which participants completed dietary questionnaires and had cardiac CT scans taken 10 years apart.2 Researchers identified 1,567 participants aged 45 to 84 years who had no coronary artery calcium at baseline. Ten years later, they found the following3:
- Participants with the highest calcium intake—more than 1,400 mg daily—had a 27 percent lower risk of coronary artery calcification (CAC) compared to those with the lowest calcium intake (less than 400 mg daily).
- Participants who took calcium supplements had a 22 percent higher risk of CAC.
It’s clear that this study demonstrates the importance of getting calcium through dietary sources. While it’s acceptable to use supplements to fill in any dietary gaps, patients must be cautioned not to exceed the safe amount, a concept that was supported by study published in the Annals of Internal Medicine in the same month as the JAMA study. After completing a literature review, researchers concluded that in healthy adults, supplementation at doses of 2,000 to 2,500 mg/day does not cause cardiovascular harm.4
You can guide patient choices using recommendations established by the Food and Nutrition Board of the Institute of Medicine5:
- Adults aged 19 to 50 years – Women and men need 1,000 mg per day
- Adults aged 51 to 70 years – Women need 1,200 mg/day; men need 1,000 mg/day
- Adults aged 71 years and older – Women and men should get 1,200 mg daily
- Tolerable upper intake level – 2,500 mg/day for adults aged 19 to 50 years; 2,000 mg/day for those aged 51 and older
Interactions Between Calcium and Medications
When dispensing medications and during subsequent medication reviews, counsel patients about potential interactions between their medication and supplemental calcium. Be sure to stress that these concerns are only relevant to supplements, not dietary sources6:
- Quinolone antibiotics – Calcium may decrease absorption of quinolones; take supplements at least one hour after antibiotics.
- Tetracycline antibiotics – Calcium can attach to these antibiotics, which lowers the amount of medication absorbed. Take calcium 2 hours before or 4 hours after taking tetracyclines.
- Bisphosphonates – Calcium inhibits absorption of bisphosphonates; take bisphosphonates at least 30 minutes before calcium or much later in the day.
- Calcipotriene – Enhances absorption of calcium; supplements should not be taken when patients are on this medication.
- Digoxin – Taking calcium along with digoxin may multiply the effects of digoxin and cause arrhythmia. Patients should consult their doctor before taking calcium supplements.
- Verapamil – Calcium supplements should not be mixed with verapamil unless under a doctor’s supervision.
- Sotalol – Calcium may decrease sotalol’s effectiveness; take calcium at least 2 hours before or 4 hours after sotalol.
- Diltiazem – Supplemental calcium may decrease effectiveness of diltiazem.
- Levothyroxine – Calcium decreases absorption of levothyroxine; take them at least 4 hours apart.
- Water pills – Water pills increase the amount of calcium in the body; calcium supplements can amplify that effect, potentially causing serious adverse effects.
Key Information for Patients Purchasing Calcium Supplements
Most types of calcium supplements should be taken with food, except for calcium citrate, which can be taken any time and is the preferred formulation for people with low stomach acid or those taking drugs that limit stomach acid production. It’s sometimes a challenge for patients to figure the cost of supplements versus the dosage because each formulation has a different amount of elemental calcium7:
- Calcium carbonate – 40 percent elemental calcium
- Calcium citrate – 21 percent elemental calcium
- Calcium gluconate – 9 percent elemental calcium
- Calcium lactate – 13 percent elemental calcium
After helping patients sort through the various types of calcium, include this information when talking with them about using supplements:
- The amount of calcium absorbed is inversely related to intake—patients should take smaller doses of less than 500 mg several times daily.
- Warn patients that some antacids contain calcium, usually 200 to 400 mg per dose, which should be included in their total supplement intake.
- Remind patients that they also need vitamin D in order to absorb calcium. Recommend supplements that contain both.
- Calcium may cause gas, bloating and constipation—calcium carbonate is most likely to cause GI problems, so patients may need to start with a lower dose and gradually increase or switch to a different formulation.
- Supplemental calcium may increase the risk of kidney stones. Patients with a history of calcium oxalate stones should consult their physician before taking supplements.
- Dairy products are the top sources of calcium, otherwise recommend dark leafy greens and vegetables.8
To determine if they need supplemental calcium, patients will need to tally the amount of calcium they typically get through their diet. They can do it manually by keeping a journal of what they eat for a few days or use an online calculator or app like My Fitness Pal.
Pharmacists can also quickly screen for those who are at risk for dietary calcium deficiency by asking patients if they fit any of the following:
- Long-term treatment with corticosteroids
- Follow a vegan diet
- Have lactose intolerance
- Limited consumption of dairy products
- Consume large amounts of protein or sodium, which leads to extra calcium excretion
- Have osteoporosis
- Have gastrointestinal disease that interferes with calcium absorption such as inflammatory bowel disease
Help Patients Maintain Optimal Calcium Intake
It’s important to know about the risks of soft tissue calcification from excessive calcium, but a bigger danger arises when patients misunderstand contradictory reports and cut down on calcium consumption. In addition to helping patients choose supplements and including calcium in medication counseling, it’s smart to refer them back to their physician or a dietitian if they have any concerns. The health of their blood vessels, nerves, muscles, and bones depends on sufficient calcium.
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- “Calcium,” August 2015, http://lpi.oregonstate.edu/mic/minerals/calcium ↩
- “Calcium Intake From Diet and Supplements and the Risk of Coronary Artery Calcifications and its Progression Among Older Adults: 10-Year Follow-up of the Multi-Ethnic Study of Atherosclerosis (MESA),” October 2016, https://www.ncbi.nlm.nih.gov/pubmed/27729333 ↩
- “Calcium From Supplements, Not Diet, Linked to Arterial Plaque Buildup,” October 2016, https://www.uspharmacist.com/article/calcium-from-supplements-not-diet-linked-to-arterial-plaque-buildup ↩
- “Calcium Intake and Cardiovascular Disease Risk: An Updated Systematic Review and Meta-Analysis,” October 2016, http://annals.org/aim/article/2571713/calcium-intake-cardiovascular-disease-risk-updated-systematic-review-meta-analysis ↩
- “Dietary Reference Intakes for Calcium and Vitamin D,” 2011, https://www.ncbi.nlm.nih.gov/books/NBK56070/ ↩
- “Calcium,” 2009, http://www.webmd.com/vitamins-supplements/ingredientmono-781-calcium.aspx?activeingredientid=781 ↩
- “Calcium Supplements / Hypocalcemia,” December 2016, http://www.globalrph.com/calcium_supplements.htm ↩
- “Top 10 Foods Highest in Calcium,” November 2016, https://www.healthaliciousness.com/articles/foods-high-in-calcium.php ↩