Immune Dysregulation and Nutrition in SARS-CoV-2 Infection: An Integrated Review with Oral Health Perspectives

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection causes not only acute respiratory illness but also dysregulated immune responses, including autoimmunity and hypersensitivity reactions, which can worsen outcomes. SARS-CoV-2 infection, known publicly as COVID-19 disease, has presented a complex clinical landscape ranging from asymptomatic infection to SARS and multi-organ failure. Beyond direct viral damage, the pathogenesis of COVID-19 is heavily driven by immune dysregulation, which causes allergic-type reactions. Nutritional status and immunonutrition further modulate these processes and play a critical role. Vitamins C and D are essential for immune competence, with vitamin C serving as an antioxidant that supports barrier integrity and leukocyte function. In contrast, vitamin D regulates innate and adaptive responses. The intake of essential nutrients could be a strategic approach to bolster the innate and adaptive immune systems, aiming to prevent infection and mitigate disease severity. Saliva and oral health are increasingly recognized as central to COVID-19 immunopathology, both as diagnostic media and as immunological barriers. This review synthesizes recent findings on autoimmune phenomena, hypersensitivity reactions, immunonutrition, and oral health in SARS-CoV-2 infection, highlighting mechanisms and clinical implications.