Immune Systems Advisor

Abstract: Healthy lifestyle factors—exercise, sunlight exposure, nutritious diet, and adequate sleep—demonstrate statistically significant efficacy in reducing the risk of SARS-CoV-2 infection and improving outcomes, consistent with their benefits against other viral pathogens. This systematic review synthesizes evidence from 119 studies, highlighting mechanisms such as enhanced immune function, increased nitric oxide production, and improved gut microbiome health. Exercise (38% risk reduction), sunlight (via vitamin D and circadian regulation), diet (nutrient-mediated immunity), and sleep (cytokine and T-cell production) collectively mitigate infection risk and severity. Post-infection benefits are also suggested, with sunlight and exercise linked to lower mortality and faster recovery. However, pandemic measures exacerbated unhealthy lifestyle trends, including reduced physical activity, poor diet, sleep disturbances, and vitamin D deficiency, amplifying vulnerability, particularly a...