Rethinking the hepatoprotective potential of vegetarian diets in dysfunction-associated steatotic liver disease/metabolic-associated fatty liver disease: a critical narrative review.

Dietary intervention is central to the management of metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as metabolic-associated fatty liver disease (MAFLD). Although vegetarian dietary patterns are widely considered hepatoprotective, emerging evidence indicates that certain individuals following non-standardized vegetarian diets may fail to obtain the expected hepatic benefits-a phenomenon termed the "vegetarian hepatoprotection paradox." This critical narrative examines the putative mechanisms underlying this paradox. Excessive intake of high-glycemic carbohydrates and fructose, which is common in some vegetarian diets, may activate hepatic de novo lipogenesis. Furthermore, incomplete plant proteins may contribute to impaired very low-density lipoprotein (VLDL)-mediated lipid export, while an imbalanced n-6:n-3 fatty acid ratio may promote hepatic inflammation. These dietary factors may interact with genetic susceptibility, including patatin-like phospholipase domain-containing protein 3 (PNPLA3) I148M and transmembrane 6 superfamily member 2 (TM6SF2) E167K variants, disrupting hepatic lipid homeostasis. Additionally, gut dysbiosis may propagate metabolic disturbance through chronic inflammation. Accordingly, a shift from the categorical vegetarian labeling toward an emphasis on plant-based dietary quality-reflecting the principle that dietary quality matters more than the vegetarian label itself-may be warranted. This review discusses evidence-based dietary patterns, including the Mediterranean diet, the Green Mediterranean diet, and the Dietary Approaches to Stop Hypertension (DASH) diet, together with chrononutrition strategies. A precision nutrition approach integrating genetic, metabolic, and microbiome characteristics may represent an emerging but still investigational framework for individualized MASLD/MAFLD interventions.