If you live by a plant-based diet, your risk of developing COVID-19 could be significantly lower than the general population, researchers from the University of Sao Paulo have claimed.
The conclusion is based on an observational study of 702 participants and their dietary patterns, published in the British Medical Journal of Nutrition, Prevention and Health.
Numerous studies have found links between diet quality and COVID-19, with the World Health Organization recommending a diet rich in fresh fruits, vegetables, legumes, nuts and whole grains to build a healthy immune system and lower your risk of infection.
To expand on this research, the team at the University of Sao Paulo recruited 702 adult volunteers between March and July 2022. The participants were surveyed on their eating patterns and food group frequency, as well as their lifestyle and medical history—including vaccinations.
In all, 330 participants reported suffering from SARS-CoV-2 infection, 15 percent of whom had experienced moderate to severe symptoms. After adjusting for confounding risk factors like BMI, physical activity and pre-existing medical conditions, those with a plant-based or vegetarian diet had a 39 percent lower chance of developing COVID-19 compared to those with an omnivorous diet. However, the study authors say that there was no association between the participants' diets and the severity or duration of their infection.
The authors suggest that this difference in infection risk could be due to the abundance of plant-derived chemicals.
"Plant-based dietary patterns are rich in antioxidants, phytosterols and polyphenols, which positively affect several cell types implicated in the immune function and exhibit direct antiviral properties," they write.
However, not everyone is convinced by this hypothesis. "The suggestion that antioxidants might be a mechanism has largely been dismissed in the scientific literature for over a decade," Duane Mellor, a registered dietitian and senior lecturer at Aston University's Medical School in the U.K., said in a statement. "It is thought that the variety of nutrients and other components in plants may reduce our risk of disease by a number of other mechanisms, including up regulating protective pathways in our liver and enhancing the health benefits of our gut microbiome."
Others are concerned about the validity of the study's findings more generally. "The authors say that 'we recommend the practice of following plant-based diets or vegetarian dietary patterns,'" Margaret Rayman, a professor of Nutritional Medicine at the U.K.'s University of Surrey, said in a statement.
"I think that this study can't provide substantial evidence for this recommendation with regards to COVID-19 infection. This is an important limitation, particularly in terms of people who may have higher nutritional needs than most, such as pregnant women.
"Furthermore, I disagree that 'predominantly plant-based diets provide more nutrients that boost the immune system and help to fight viral infections.' In fact, the opposite is the case."
Rayman continued: "A recent study assessed 141 observational/intervention studies published since 2000 that looked at nutrient intake and status in adult populations consuming vegetarian, vegan or meat-eating diets. Intake of vitamin B12, iodine, iron, zinc, calcium, vitamin D and bone turnover markers were generally lower in plant-basedversus meat-eater dietary patterns as these micronutrients are mostly found in animal foods or, in the case of iron, zinc and calcium, have a lower bioavailability in plant foods."
Moreover, the study's small sample size throws doubt on the wider applicability of its conclusions. "This study is observational and does not include confirmation of diagnosis, and although the researchers corrected for ethnicity, education and other factors associated with risk of COVID-19 infection, the small sample size might have meant that any association could be a statistical error," Mellor said.
Is there a health issue that's worrying you? Do you have a question about diet and COVID-19? Let us know via health@newsweek.com. We can ask experts for advice, and your story could be featured on Newsweek.
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Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
About the writer
Pandora Dewan is a Senior Science Reporter at Newsweek based in London, UK. Her focus is reporting on science, health ... Read more
