Sustainable dietary patterns and gastric cancer risk

Introduction: The EAT-Lancet commission proposed the Planetary Health Diet (PHD) as a sustainable dietary pattern designed to promote both human and planetary health. It is characterized by a high intake of plant-based foods and a limited consumption of animal-derived products. Several indexes have been developed to evaluate adherence to this dietary pattern, including the EAT-Lancet Index (EAT-LI), two versions of the Planetary Health Diet Index developed by Bui et al. (PHDI-B) and Cacau et al. (PHDI-C), and the World Index for Sustainability and Health (WISH). However, the association between PHD and gastric cancer (GC) has not been previously investigated. Objectives: To investigate the association between adherence to the PHD and GC risk. Methods: We applied four indexes assessing PHD adherence (EAT-LI, PHDI-B, PHDI-C, and WISH) to individual-level data from 10 case-control studies included in the international Stomach Cancer Pooling (StoP) Project. For the present analysis, we considered 3748 cases and 9056 controls. Study-specific odds ratios (ORs) and the corresponding 95% confidence intervals (CI) were estimated using multivariable logistic regression, modelling each index per 10% increment in adherence and by study-specific quartiles. Pooled estimates were then derived using random-effects models. Results: All indexes were inversely associated with GC risk. The pooled ORs per 10% higher adherence were 0.70 (95% CI: 0.61-0.81) for PHDI-B, 0.76 (95% CI: 0.68-0.85) for PHDI-C, 0.76 (95% CI: 0.66-0.88) for EAT-LI and 0.79 (95% CI: 0.72-0.86) for WISH. The ORs of the highest versus the lowest adherence quartiles ranged from 0.34 for EAT-LI to 0.63 for PHDI-C. Associations were consistent across intestinal and diffuse histological tumours, for cardia and non-cardia GC subtypes, across strata of several covariates, and after adjustment for Helicobacter pylori infection. Conclusions: Higher adherence to the PHD was associated with lower GC risk across different indexes and populations. These findings indicate that dietary sustainability and health can coexist on a public and planetary health level.