A meta-analysis of 15 randomized controlled trials found that calcium supplements, without coadministered vitamin D, are associated with an increased risk of myocardial infarction. The study included 15 trials with a total of 12,921 participants, with a median follow-up of 4.0 years. In trials with patient-level data, 143 participants allocated to calcium had a myocardial infarction compared to 111 in the placebo group (hazard ratio 1.31, 95% CI 1.02-1.67, P=0.035). Trial-level data also showed an increased risk of myocardial infarction in those allocated to calcium (pooled relative risk 1.27, 95% CI 1.01-1.59, P=0.038). While there were non-significant increases in stroke, the composite endpoint of myocardial infarction, stroke, or sudden death, and death, the overall risk of cardiovascular events was increased with calcium supplementation. The study suggests that even modest increases in risk from calcium supplements could translate into a significant burden of disease in the population due to their widespread use. The findings indicate that calcium supplements may increase vascular calcification and cardiovascular events, particularly in those with high dietary calcium intake. The study also notes that calcium supplements have modest efficacy in reducing fractures but may have adverse effects on cardiovascular health. The results suggest that the role of calcium supplements in the prevention and treatment of osteoporosis should be reassessed.A meta-analysis of 15 randomized controlled trials found that calcium supplements, without coadministered vitamin D, are associated with an increased risk of myocardial infarction. The study included 15 trials with a total of 12,921 participants, with a median follow-up of 4.0 years. In trials with patient-level data, 143 participants allocated to calcium had a myocardial infarction compared to 111 in the placebo group (hazard ratio 1.31, 95% CI 1.02-1.67, P=0.035). Trial-level data also showed an increased risk of myocardial infarction in those allocated to calcium (pooled relative risk 1.27, 95% CI 1.01-1.59, P=0.038). While there were non-significant increases in stroke, the composite endpoint of myocardial infarction, stroke, or sudden death, and death, the overall risk of cardiovascular events was increased with calcium supplementation. The study suggests that even modest increases in risk from calcium supplements could translate into a significant burden of disease in the population due to their widespread use. The findings indicate that calcium supplements may increase vascular calcification and cardiovascular events, particularly in those with high dietary calcium intake. The study also notes that calcium supplements have modest efficacy in reducing fractures but may have adverse effects on cardiovascular health. The results suggest that the role of calcium supplements in the prevention and treatment of osteoporosis should be reassessed.