Cardiovascular risks associated with calcium supplementation in patients with osteoporosis: a nationwide cohort study

Aims: This study aimed to evaluate the real effects of calcium supplementation on cardiovascular outcomes within a population-based cohort.

Methods and results: From a nationwide health screening database in South Korea, a total of 11 297 patients with osteoporosis who had taken calcium supplementation with or without vitamin D for at least 90 days [total calcium group; calcium supplementation only (CaO), n = 567; calcium supplementation in combination with vitamin D (CaD), n = 10 730] were matched at a 1:1 ratio to patients who had not taken calcium supplements (control group) by using propensity scores. The overall mean age was 59.9 ± 8.8 years and the percentage of women was 87.9% in our study population. Over a median follow-up of 54 months, the incidence rate of composite cardiovascular diseases (CVDs) per 1000 person-years was not different between the groups: 9.73 in the total calcium group and 8.97 in the control group [adjusted hazard ratio (HR): 1.12; 95% confidence interval (CI): 0.99-1.28; P = 0.08]. However, calcium supplementation without vitamin D was associated with an increased risk of composite CVD (HR: 1.54; 95% CI: 1.17-2.04; P < 0.01), especially non-fatal myocardial infarction (HR: 1.89; 95% CI: 1.23-2.91; P < 0.01), compared with no calcium supplementation.

Conclusion: Our population-based study supported that taking calcium supplementation combined with vitamin D did not appear to be harmful to cardiovascular health, but reminded that calcium supplementation without vitamin D should be used carefully even in populations with low dietary calcium intake.