Abstract
BACKGROUND: Growing evidence has indicated that alterations in the gut microbiota and nutritional quality of dietary intake were associated with COVID-19. Whether these associations reflect causality is still unknown. METHODS: We performed a two-sample Mendelian randomization analysis using genetic variants as instrumental variables for gut microbiota, dietary component intake, and COVID-19. FINDINGS: We found that the Ruminococcustorques group genus was significantly associated with COVID-19. The Ruminococcaceae UCG013 genus and Ruminococcus1 genus were suggestively associated with COVID-19. The Actinobacteria class, Bifidobacteriales order, Bifidobacteriaceae genus, R. group, and Tyzzerella3 genus were potentially associated with severe COVID-19. COVID-19 was significantly associated with the Lachnospira genus, Oscillospira, and RuminococcaceaeUCG009 genus and potentially associated with the Victivallis genus. Severe COVID-19 was significantly associated with the Turicibacter and Olsenella genus and potentially associated with Ruminococcus1, CandidatusSoleaferrea, and Parasutterella genus. Moreover, processed meat intake was significantly associated with COVID-19. Beef intake was suggestively associated with COVID-19. Salt added to food intake, and fresh fruit intake was suggestively associated with severe COVID-19. CONCLUSIONS: Our findings provide evidence supporting a causal effect of gut microbiota and dietary intake on COVID-19. We also found the causal effect of COVID-19 on the alteration of gut microbiota.