Objective: The dietary acid load can contribute to metabolic acidosis, which is closely linked to cancer development through mechanisms of inflammation and cell transformation. However, very limited epidemiologic evidence is linking diet-dependent acid load and cancer risk. Since no published studies focused on dietary acid load and gastric cancer (GC) risk, we explored this association in the present study.

Patients and Methods: A case-control study was performed in 1370 patients (274 cases and 1096 age-frequency, sex, and urban/rural residence matched controls) through a multi-topic inquiry, including a food frequency questionnaire. Food-derived nutrients were calculated from available databases. The dietary acid load was calculated based on two validated measures: Potential Renal Acid Load (PRAL) score and Net Endogenous Acid Production (NEAP) score. Odds ratios (OR) and their 95% confidence intervals (95% CI) were estimated by unconditional logistic regression, adjusting for potential confounders.

Results: We found direct, significant associations between dietary acid load and GC risk: (OR=1.74, 95% CI 1.13-2.66) and (OR=1.90, 95% CI 1.26-2.84) for highest PRAL and NEAP, respectively. Both risk estimates also displayed linear trends. Both acid load scores were directly associated with animal-based foods (mainly meat) and inversely associated with the intake of plant-based foods.

Conclusions: A high dietary acid load may contribute to GC development. To the best of our knowledge, the present is the first epidemiologic case-control study analyzing associations of dietary acid load and GC risk in a Western population. Further research is warranted to confirm our findings.