Objective: Dietary acid load can contribute to metabolic acidosis, which is closely linked to cancer development through inflammation and cell transformation mechanisms. However, limited epidemiologic evidence is still linking diet-dependent acid load and cancer risk. Since we published nine studies specifically focusing on dietary acid load and the risk of cancer development, we decided to explore its potential role more deeply through the analysis of all databases combined.

Materials and methods: A case-control study was performed on 13270 subjects (3736 cases and 9534 age-frequency and residence-matched controls) drawn from the major public hospitals in Uruguay. Participants were interviewed through a multi-topic questionnaire, including a food frequency questionnaire. Food-derived nutrients were calculated from available databases. The dietary acid load was calculated based on validated measures, including Potential Renal Acid Load and Net Endogenous Acid Production scores. Odds ratios (OR) were estimated by logistic regression, adjusting for potential confounders.

Results: We found significant and direct associations between dietary acid load and cancer risk (OR= 1.44 and OR= 1.64 for the highest scores). The estimated methionine intake was found also significantly and directly associated (OR= 1.97), while the plant fiber was significantly and inversely associated (OR= 0.49).

Conclusions: Results confirm that an acidogenic dietary style may increase the risk of cancer. Our findings suggest that both Met and plant fiber intakes might be independent factors influencing the risk linked to acid-base disbalance which turn into a metabolic stress, but acting in opposite directions. Furthermore, Met intake displayed comparable odds ratios as the scores themselves.