Is calcium supplementation increasing your risk of cardiovascular disease? Original paper

The National Osteoporosis Foundation’s current guidelines for the prevention and treatment of osteoporosis recommend calcium supplements for adults aged 50+ who don’t get enough calcium through their diets. Some meta-analyses, however, have associated calcium supplementation with an increased risk of cardiovascular events; but other studies have failed to replicate these findings.

This meta-analysis included 13 randomized controlled trials that looked for associations between calcium supplementation and cardiovascular events in 28,935 adults (93% women) aged 35–97.

The trials looked at cardiovascular disease (CVD) incidence, coronary heart disease (CHD) incidence, and cerebrovascular disease (CBD) incidence and mortality.

In the overall analyses, calcium supplementation increased the risks of CVD (relative risk: 1.15) and CHD (relative risk: 1.16), but not of CBD. In the subgroup analyses, these effects were statistically significant for these four subgroups: CVD and CHD incidence, healthy postmenopausal women, participants with dietary calcium intakes of 700–1,000 mg/day, and participants with supplementary calcium intakes of 1,000 mg/day. Overall, the absolute increase in risk from calcium supplements was 8.6 per 1,000 participants (CVD) and 8.8 per 1,000 participants (CHD).

Calcium supplementation increased the risk of CVD and CHD in the trials with a lower risk of bias, but not in the trials with a higher risk of bias.

No heterogeneity was detected in the main analyses and most of the subgroup analyses (meaning that the analyzed studies didn’t differ greatly in their characteristics).

The inclusion of only double-blind randomized placebo-controlled trials, the homogeneity between trials, and the findings from the subgroup analyses that included only trials with a low risk of bias increase our confidence in the results.