COMMENTARY

Calcium Supplements and the Heart: Clearing Up the Confusion

JoAnn E. Manson, MD, DrPH

Disclosures

November 09, 2016

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Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women's Hospital. I'd like to talk with you about calcium supplements and the heart. This is a subject that has been filled with mixed messages and prone to confusion over the past several years.

Recent reports[1,2,3] published in Annals of Internal Medicine in October 2016 provide increased clarity on this subject. An updated systematic review and meta-analysis, extensively reviewing the evidence on dietary calcium as well as calcium from supplements (with or without vitamin D) and the risks for heart disease and stroke, provided no evidence for a link. No clear association was found.

In an accompanying set of guidelines from the National Osteoporosis Foundation and the American Society for Preventive Cardiology,[2] the same conclusion was reached, and the authors stated that as long as the intake of calcium from food or supplements does not exceed the guidelines—the range of intake set by the Institute of Medicine[4]—it should be considered safe from a cardiovascular standpoint. The Institute of Medicine has recommended 1000-1200 mg of calcium daily for most adults, and the tolerable upper intake level has been set at 2000-2500 mg of calcium daily. For vitamin D, the recommended intake is 600-800 IU daily for adults, not exceeding 4000 IU daily.

We know that both calcium and vitamin D are essential for bone health, but concerns have been raised from selected reports in recent years about heart risk. Even a recent observational study from the MESA cohort[5] suggested an association between calcium supplements and coronary artery calcium, but it's important to note that in observational studies, association does not prove causation. There are other reasons that there could be an association, such as overlapping risk factors for osteoporosis and heart disease, including smoking and lack of exercise. In the large-scale Women's Health Initiative calcium and vitamin D trial,[6] we found no association between calcium and vitamin D supplementation and coronary artery calcium measured at the end of the 7-year trial.

I want to acknowledge that we were invited to write an editorial[3] to accompany these papers. My colleague, Dr Karen Margolis, and I agreed with the findings of the lack of a clear association, but we did recommend trying to achieve the guidelines for intake of calcium from dietary sources if at all possible, and then using calcium supplements only to fill the gap. There are many dietary sources of calcium, including dairy products (milk, yogurt, cheese), fatty fish with bones (such as sardines), fortified beverages, and leafy greens. Many people are able to obtain 700-1000 mg calcium daily from dietary sources, and many will need only 500 mg daily in calcium supplements or even less.

An important principle is that more is not necessarily better.

These reports in Annals of Internal Medicine provide important information for public health and clinical guidelines, and we hope you find them helpful in your own clinical practice. Thanks for your attention. This is JoAnn Manson.

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