The study’s findings lead the researchers to propose that adopting a diet rich in vegetables, legumes, and nuts while minimizing the intake of dairy products and meat could potentially play a role in preventing COVID-19 infection. This suggestion is rooted in a growing body of research that indicates diet may significantly influence the progression of COVID-19 infection and the severity of its related complications.
To explore the possible effects of dietary habits on the risk and outcome of COVID-19, the researchers embarked on a study involving 702 adults. These volunteers were recruited between March and July 2022 and were assessed for their dietary patterns, frequency of consumption of various food groups, lifestyle choices, and medical histories, including COVID-19 vaccination status. The study categorized the participants into two primary dietary groups: omnivorous (424 participants) and predominantly plant-based (278 participants).
Within the plant-based category, participants were classified as flexitarians/semi-vegetarians, who consumed meat no more than three times a week (87 participants), and vegetarians or vegans (191 participants). Individuals adhering to plant-based or vegetarian diets typically consume higher amounts of vegetables, legumes, and nuts and lower to no dairy and meat products.
The demographic analysis revealed no significant differences in sex, age, or vaccination rates between the omnivorous and plant-based groups. However, a notably higher proportion of the plant-based group had attained a postgraduate level of education. Additionally, the omnivorous group reported a greater prevalence of medical conditions and lower levels of physical activity, alongside a significantly higher incidence of overweight and obesity—factors all linked to an increased risk of contracting COVID-19 and experiencing more severe symptoms or complications.
Out of the total participants, 330 (47%) reported having contracted COVID-19, with 224 (32%) experiencing mild symptoms and 106 (15%) facing moderate to severe symptoms. Notably, the incidence of COVID-19 was significantly higher among the omnivores compared to those in the plant-based dietary groups (52% vs. 40%), with a greater tendency towards moderate to severe infection (18% vs. just over 11%).
Despite these findings, no difference was observed in the duration of symptoms between the two groups. However, after adjusting for variables like weight, pre-existing medical conditions, and physical activity levels, researchers found no significant difference in symptom severity. However, individuals following a predominantly plant-based or vegetarian/vegan diet had a 39% lower risk of infection compared to omnivores.
The researchers suggest that plant-based diets, abundant in antioxidants, phytosterols, and polyphenols, may bolster the immune system’s ability to combat viral infections, including COVID-19. These nutrients are known to impact various cells involved in immune function positively and possess antiviral properties.
Although this study is observational and cannot establish causality, its conclusions are significant. The researchers acknowledge the limitations of relying on self-reported data, which is subject to recall bias and subjective assessment errors. Nonetheless, they advocate for adopting plant-based or vegetarian diets as a precautionary measure against COVID-19, in line with other studies’ findings on the impact of dietary patterns on the disease’s incidence.
Shane McAuliffe, Senior Visiting Academic Associate at the NNEdPro Global Institute for Food, Nutrition and Health, highlights the importance of this research in adding to the evidence that diet may influence susceptibility to COVID-19 infection. However, McAuliffe also calls for more thorough and high-quality research before drawing definitive conclusions about the relationship between specific dietary patterns and the risk of COVID-19 infection.
More information: Júlio César Acosta-Navarro et al, Vegetarian and plant-based diets associated with lower incidence of COVID-19, BMJ Nutrition Prevention & Health. DOI: 10.1136/bmjnph-2023-000629
Journal information: BMJ Nutrition Prevention & Health
