Calcium supplements have been shown to decrease the risk of colorectal adenomas. In this issue of the Journal, Shaukat et al. report the results of a systematic review and meta-analysis of randomized controlled trials of calcium supplementation. The authors statistically combined the data from the three trials that met strict eligibility criteria. The overall relative risk was 0.80 (95% CI: 0.68-0.93) and the number needed to treat was 14. The results of this meta-analysis support a preventive role for calcium supplements.