Sustainable Plant-Based Diets and Food Allergies: A Scoping Review Inspired by EAT-Lancet

Background: The escalating prevalence of food allergies, alongside the global call for environmentally sustainable dietary transitions, has drawn attention to plant-based dietary models—particularly those inspired by the EAT-Lancet Commission. These frameworks not only reduce reliance on animal-sourced foods, benefiting planetary health, but may also play a role in modulating immune tolerance and allergic responses. Methods: This scoping review followed PRISMA guidelines and included 53 peer-reviewed studies published between 2000 and 2024, retrieved from PubMed, Scopus, and Google Scholar. Eligible articles were classified into two thematic domains: prevention of food allergy onset (n = 31) and modulation of allergic symptoms in sensitized individuals (n = 22). Included studies comprised randomized controlled trials (n = 6), observational studies (n = 17), systematic reviews and meta-analyses (n = 11), and narrative/scoping reviews (n = 19). Results: Sustainable plant-based diets were consistently associated with a lower incidence of allergic sensitization and reduced symptom severity. These effects were partly due to the exclusion of common allergens (e.g., dairy, eggs, and shellfish) but more importantly due to immunomodulatory mechanisms. Fermentable fibers can enhance short-chain fatty acid (SCFA)-producing bacteria (e.g., Faecalibacterium prausnitzii), elevating butyrate and acetate levels, which interact with G-protein-coupled receptors 43 and 109A (GPR43 and GPR109A) to induce regulatory T cells (Tregs) and reinforce epithelial integrity via tight junction proteins such as occludin and claudin-1. Polyphenols (e.g., quercetin and luteolin) can inhibit Th2-driven inflammation by stabilizing mast cells and downregulating IL-4 and IL-1. Conclusions: Following sustainable dietary guidelines such as those proposed by the EAT-Lancet Commission may confer dual benefits: promoting environmental health and reducing the burden of allergic diseases. By emphasizing plant-based patterns rich in fiber and polyphenols, these diets support microbiota-mediated immune education, mucosal barrier function, and immunological tolerance. When properly supervised, they represent a promising tool for allergy prevention and symptom management. Larger randomized trials and long-term population studies are needed to confirm and operationalize these findings in clinical and public health contexts.