From the Journals

Guideline: Supplemental, dietary calcium both heart safe

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Evidence is abundant but has limitations

The volume of literature on the subject of calcium’s potential harmful cardiovascular disease effects appears to be robust, with the largest meta-analysis to date including 18 studies with 64,000 participants. But this evidence base has some limitations, chief among them the fact that none of the studies was designed to evaluate CVD as a primary outcome.

In addition, concerns about harmful cardiovascular effects arose after most of the trials had already been initiated, so unpublished data on those outcomes were collected and adjudicated retrospectively. In addition, many of the participants showed poor long-term treatment adherence, making it difficult to interpret the data.

Karen L. Margolis, MD, of HealthPartners Institute in Minneapolis and JoAnn E. Manson, MD, DrPH, of Brigham and Women’s Hospital and Harvard Medical School, both in Boston, made these remarks in an editorial accompanying the new Clinical Practice Guideline (Ann Intern Med. 2016 Oct 24. doi: 10.7326/M16-2193). Their financial disclosures are available at


Both dietary and supplemental calcium should be considered safe for the cardiovascular system as long as total intake doesn’t exceed 2,000-2,500 mg/day – the maximal tolerable level defined by the National Academy of Medicine, according to an updated Clinical Practice Guideline published online October 24 in Annals of Internal Medicine.

For generally healthy patients who don’t consume adequate calcium and take supplements, either alone or in combination with vitamin D, to prevent osteoporosis and related fractures, “discontinuation of supplemental calcium for safety reasons is not necessary and may be harmful to bone health,” said Stephen L. Kopecky, MD, of the Mayo Clinic, Rochester Minn., and his associates on the expert panel that wrote the new guideline.

An image of two bones riddled with osteoporosis is shown, over a background of osetoporotic bone. ©iStock/
The U.S. Agency for Healthcare Research and Quality published an Evidence Report in 2009 concerning the effect of both calcium and vitamin D on health outcomes, including cardiovascular disease. But since then, “conflicting reports have suggested that calcium intake, particularly from supplements, may have either beneficial or harmful effects on cardiovascular outcomes,” Dr. Kopecky and his associates said.

The National Osteoporosis Foundation (NOF) and the American Society for Preventive Cardiology (ASPC) commissioned an independent review of the current evidence to update the Evidence Report and assembled the expert panel to write the guideline based on the new findings (Ann Intern Med. 2016 Oct 24. doi: 10.7326/M16-1743).

Separately, Mei Chung, PhD, of the department of public health and community medicine, and her associates at Tufts University, Boston, reviewed 4 recent randomized clinical trials, 1 nested case-control study, and 26 cohort studies that assessed the effects of calcium intake on 17 health outcomes in generally healthy adults of all ages. None of the studies evaluated cardiovascular disease risk as a primary outcome. “We conclude that calcium intake (from either food or supplement sources) at levels within the recommended tolerable upper intake range (2,000-2,500 mg/d) are not associated with CVD risks in generally healthy adults,” they said.

“Although a few trials and cohort studies reported increased risks with higher calcium intake, risk estimates in most of those studies were small (10% relative risk) and not considered clinically important, even if they were statistically significant,” Dr. Chung and her associates added (Ann Int Med. 2016 Oct 24. doi: 10.7326/M16-1165).

According to the guideline, “The NOF and the ASPC now adopt the position that there is moderate-quality evidence that calcium with or without vitamin D intake from food or supplements has no relationship (beneficial or harmful) with the risk for cardiovascular or cerebrovascular disease, mortality, or all-cause mortality in generally healthy adults at this time.”

In addition, “Currently, no established biological mechanism supports and association between calcium and cardiovascular disease,” Dr. Kopecky and his associates on the expert panel noted.

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