# Metadata Source URL:: https://www.nature.com/articles/s42255-022-00646-1 Topics:: #health --- # Fasting as key tone for COVID immunity - Nature Metabolism SARS-CoV-2-induced anorexia triggers systemic metabolic alterations. In a study published in Nature, Karagiannis et al. show that the ketone body β-hydroxybutyrate (BHB) improves COVID-19 disease outcomes. Further, BHB metabolically and functionally reprograms CD4+ T cells, highlighting immunometabolic tuning of immunity in COVID-19. ## Highlights > [!quote]+ Updated on 310123_101435 > > Overall, this study has identified the ketone body BHB as an alternative carbon source to fuel mitochondrial OXPHOS, thereby metabolically reprogramming TH1 cells and improving antiviral immunity in conditions of infection-induced anorexia. Considering the diverse cellular signalling activities of BHB3, it is possible that BHB alters CD4+ T cell function through additional means such as transcriptional regulation or epigenetic modifications, consistent with a role for BHB in controlling CD8+ memory T cell development via epigenetic regulation15. As metabolic programs are crucial regulators of CD4+ and CD8+ T cell plasticity and heterogeneity9, additional studies are required to address whether BHB and other metabolites induced by a ketogenic diet have similar effects on other types of T cell during viral infection or in other nutrient-deprived contexts, including the tumour microenvironment. In summary, these important findings broaden our knowledge of dietary influence on antiviral immunity and provide new insights into and understanding of the variable morbidity associated with COVID-19.