Trash the Calcium, Save the Patient

A Best Evidence Review

Charles P. Vega, MD


March 07, 2013

In This Article

Study Design and Results

Researchers analyzed data from the National Institutes of Health-American Association of Retired Persons (AARP) Diet and Health Study. This research enrolled AARP members between 50 and 71 years of age in 8 states. Participants were generally healthy at baseline, and individuals at the extremes of total energy and dietary calcium intake were excluded from study analysis.

A 124-item food-frequency questionnaire was used to assess participants' dietary calcium intake. This survey also queried the use of supplements, and participants completed a baseline questionnaire that included demographic, disease, anthropometric, and lifestyle information.

The main study outcome was the effect of calcium intake on the risk for CVD death, as defined by mortality caused by heart disease or stroke. National databases were used to access participants' vital status and causes of death. A previous study found that the accuracy of this method was 95%. Researchers adjusted their results to account for potential confounding variables.

The analysis included data from 388,229 adults. In all, 56% of women and 23% of men reported using calcium supplements; and the respective proportions of women and men who took multivitamins containing calcium were 58% and 56%. Participants who used calcium supplements were more likely to be non-Hispanic white persons, have a college education, have healthier lifestyle habits, and report better overall self-rated health.

During a mean of 12 years of follow-up, there were 7904 CVD deaths among men and 3874 CVD deaths among women in the study. A significant trend was seen toward a reduction in the risk for death due to heart disease with greater dietary calcium intake among men, but dietary calcium intake did not affect the risks for stroke death in either sex or any CVD death among women.

Among men, daily supplemental calcium at a dosage of 1000 mg/day or more was associated with significant increases in the risks for overall CVD death (relative risk, 1.20; 95% CI, 1.05-1.36) and heart disease death (relative risk, 1.19; 95% CI, 1.03-1.37). There was a nonsignificant trend toward a higher risk for stroke death associated with the use of calcium supplements. The low number of deaths caused by stroke overall reduced the power of the study to evaluate this outcome.

Among women, calcium supplements did not independently affect the risks for death from CVD, heart disease, or stroke.

The risk for death among men who used calcium supplements appeared to be particularly high among smokers. There was a U-shaped curve relationship between total calcium intake and the risk for CVD mortality among men, but this was not found among women.