Dietary acid load and esophageal cancer risk: A case-control study.

Background: A high dietary acid load (DAL) can produce metabolic acidosis, which is linked to cancer development through mechanisms of inflammation and cell transformation. There is limited epidemiological evidence linking DAL and cancer risk; however, none of the published studies focused on DAL and esophageal cancer (EC) risk in particular. Therefore, we sought to explore this association in the present study.

Methods: A case-control study was performed in 1295 male patients (185 squamous cell EC cases and 1110 age-frequency and urban/rural residence matched controls) through a multitopic inquiry, including a food frequency questionnaire. Food-derived nutrients were calculated from available databases. The DAL 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 confounders.

Results: We found direct, significant associations between dietary acid load and EC risk: (OR = 2.28, 95% CI: 1.44-3.61, ptrend <0.0001) and (OR = 2.17, 95% CI: 1.38-3.41, ptrend <0.0001) for highest PRAL and NEAP tertiles, respectively. Our data raise the possibility that a high DAL may contribute to EC development. Both acid load scores were directly associated with animal-based foods (mainly meat) and inversely associated with the intake of plant-based foods.

Conclusion: To the best of our knowledge, this is the first epidemiological case-control study analyzing associations of DAL and squamous cell EC risk. Further research is warranted to confirm our findings.