No link seen between calcium intake with or without vitamin D and CVD in healthy adults

In a new clinical guideline, the National Osteoporosis Foundation and the Society for Preventive Cardiology state that calcium intake of 2,000 to 2,500 mg/d with or without vitamin D should be considered safe from a cardiovascular standpoint in generally healthy adults.

The guideline was based on an update and reanalysis of 2 earlier systematic reviews. The updated review looked at randomized trials and prospective cohort and nested-case control studies that included data on cardiovascular outcomes and dietary or supplemental intake of calcium with or without vitamin D and were published in English from 1966 to July 2016. In the randomized trials, no statistically significant differences were seen in risk for cardiovascular disease (CVD) events or mortality for patients receiving calcium supplements with or without vitamin D and those receiving placebo. In the cohort studies, no consistent dose-response relationship was seen between total, dietary, or supplemental calcium and cardiovascular death, and dose-response relationships between intake of calcium and risk for stroke or death from stroke were very inconsistent. The review authors noted that outcomes of CVD were secondary end points in all of the included trials, that they included only English-language studies, and that data on very high calcium intake were scarce, among other limitations.

Based on this review, the guideline stated that moderate-quality evidence showed no relationship between intake of calcium with or without vitamin D from food or supplements and risk for CVD and cerebrovascular disease or mortality or all-cause mortality and that total calcium intake at or below the tolerable upper level as defined by the National Academy of Medicine (2,000 to 2,500 mg/d) should be considered safe. The guideline authors stated that obtaining calcium from food rather than supplements is preferred but that supplements can be used safely in patients whose calcium intake is not sufficient. “Discontinuation of supplemental calcium for safety reasons is not necessary and may be harmful to bone health when intake from food is suboptimal,” the guideline authors wrote.

The authors of an accompanying editorial said that available evidence in this area is “limited and imperfect” and questioned how clinicians and patients should respond. They agreed with the guideline authors that dietary sources of calcium are preferable to supplements and also noted that no evidence supports the theory that calcium intake over the recommended dietary allowance has health benefits.

“Supplements may be used to make up but not exceed the gap between dietary intake and the recommended intake level; however, most persons require no more than 500 mg of supplemental calcium to meet their daily needs if not met by diet alone,” the editorialists wrote, noting that it is also essential to achieve recommended daily intakes of vitamin D. “Based on the totality of evidence for both calcium and vitamin D, more is not better.”