Calcium intake and gastric cancer risk: a systematic review and dose–response meta-analysis of observational studies

Abstract

Calcium has been proposed as a protective factor against certain types of cancer, but findings related to gastric cancer (GC) are inconsistent. This meta-analysis aimed to assess the association between calcium intake and the risk of GC. A comprehensive search was conducted in PubMed, Scopus, EMBASE, LILACS, and Web of Science for cohort and case-control studies published up to August 19, 2024. The quality of the studies was assessed using the Newcastle–Ottawa Scale. Publication bias was tested using Egger’s and Begg’s tests. Relative risks (RRs) and 95 % confidence intervals (CIs) were pooled through a random-effects model. Given the substantial heterogeneity and potential variation in intake levels across populations, a dose-response analysis was conducted to explore potential trends across the full range of calcium consumption. Thirteen studies involving 1,610,992 participants met the inclusion criteria. A non-significant inverse association was observed between total calcium intake and GC risk when comparing the highest vs lowest intake categories (RR: 0.85; 95 % CI: 0.70–1.05). While this categorical comparison was not statistically significant, the dose-response analysis revealed a significant linear protective effect, with a 10 % reduction in risk per 300 mg/day increase in dietary calcium intake (RR: 0.90; 95 % CI: 0.82–0.99). To account for potential variations across intake levels, a non-linear model was also applied, indicating a clearer risk reduction above 400 mg/day (p for non-linearity < 0.001). Overall, this dose-response meta-analysis suggests that higher dietary calcium intake may have a protective effect against GC, reinforcing the importance of considering calcium in dietary strategies for GC prevention, although more studies are needed to confirm these findings.