The Impact of Diet Quality on COVID-19 Severity and Outcomes—A Scoping Review

A comprehensive literature search identified 15 studies across diverse populations. Prospective cohort studies generally found higher diet quality associated with lower COVID-19 infection rates. Case-control studies consistently showed reduced odds of COVID-19 infection and severe illness with adherence to anti-inflammatory dietary patterns, particularly the Mediterranean diet. Cross-sectional data revealed associations between higher DQS and reduced COVID-19 symptom burden and improved prognostic biomarkers. An ecological study demonstrated inverse relationships between national-level diet quality and COVID-19 caseloads. Mediterranean, Dietary Approaches to Stop Hypertension (DASH), and plant-based diet scores were notably predictive of favourable outcomes, even after adjusting for confounders. Conversely, consumption of processed foods high in saturated fats, sugars, and additives was linked to increased COVID-19 complications. Despite these findings, research gaps remain, including the impacts of specific dietary components, effect modifiers across populations, and establishing causality through interventional trials. This review highlights the observational evidence supporting the potential integration of optimal nutrition into pandemic preparedness strategies. Further research is needed to strengthen these findings and inform evidence-based dietary recommendations for COVID-19 prevention and management.