New guideline on calcium and vitamin D supplementation

A new evidence-based clinical guideline from the National Osteoporosis Foundation (NOF) and the American Society for Preventive Cardiology (ASPC) says that calcium with or without vitamin D intake from food or supplements that does not exceed the tolerable upper level of intake (2,000 to 2,500 mg/d) should be considered safe from a cardiovascular standpoint. Obtaining calcium from food sources is preferred, but supplements can be used to address dietary shortfalls. The guideline is published in Annals of Internal Medicine.

Calcium supplements have been recommended for persons who do not consume adequate calcium from their diet as a standard strategy for preventing osteoporosis-related fractures. Conflicting reports have suggested that calcium intake, particularly from supplements, may have either beneficial or harmful effects on cardiovascular outcomes. To update the evidence on calcium and vitamin D, investigators from the Tufts University School of Medicine reviewed randomized trials and prospective cohort studies published since their last evidence report in 2009. Their findings were used to inform the joint clinical guideline from NOF and ASPC.

A total of 31 studies were included in the review. Of the four randomized trials reviewed, none found a statistically significant difference in risk for cardiovascular events or mortality between groups receiving supplements of calcium alone or calcium plus vitamin D compared to those receiving placebo. None of the 27 cohort studies included in the review conclusively linked total, dietary, or supplemental calcium intake levels to cardiovascular disease and cerebrovascular disease, mortality, or all-cause mortality. Because excessive calcium intake is nearly impossible to achieve via diet, safety of supplementation had been an area of concern. Of the three supplementation-specific trials included in the review, none found a statistically significant effect of calcium supplementation on cardiovascular disease outcomes. Based on this moderate-quality evidence, the review team concluded that calcium intake from food or supplement sources at levels within the recommended tolerable range should be considered safe for generally healthy adults.