Vegetarian and plant-based diets associated with lower incidence of COVID-19.

Objective: To evaluate the influence of dietary patterns on the incidence and evolution of COVID-19. We hypothesised that a plant-based diet or a vegetarian diet compared with an omnivorous diet might be associated with a lower incidence of COVID-19 infection and severity in those infected.

Design: In this observational study, 702 participants provided information on sociodemographic characteristics, dietary information and COVID-19 outcomes between March and July of 2022. Individuals were divided into two groups based on their dietary habits, omnivorous (n=424) and plant-based (n=278). The plant-based group was further divided into vegetarian and flexitarian subgroups. The groups were compared with respect to the incidence of COVID-19 infection, severity and duration. We used multivariable logistic regression models to evaluate the influence of dietary patterns.

Results: Plant-based and vegetarian groups had a higher intake of vegetables, legumes and nuts, and lower intake of dairy and meat. After adjusting for important confounders, such as body mass index, physical activity and pre-existing medical conditions, the plant-based diet and vegetarian group had 39% (OR=0.61, 95% CI 0.44 to 0.85; p=0.003) and 39% (OR 0.61, 95% CI 0.42 to 0.88; p=0.009) lower odds of the incidence of COVID-19 infection, respectively, compared with the omnivorous group. No association was observed between self-reported diets and COVID-19 severity or duration.

Conclusion: Plant-based and mainly vegetarian diets were associated with a lower incidence of COVID-19 infection. These dietary patterns may be considered protective against COVID-19 infection. (Study protocol registered in CAAE: 54351421.4.0000.0068.).