Plant-Based Diet Linked to COVID-19 Risk and Severity

Somi Igbene PhD ANutrSeptember 18, 2021

A healthy plant-based diet is linked to a lower risk and severity of COVID-19, a new observational study reports. 

In the study, participants eating plant-rich diets had a 9% lower risk of developing COVID-19 and a 41% lower risk of developing severe COVID-19 than participants eating diets with fewer plant foods. 

“We found that a dietary pattern characterised by healthy plant foods was associated with lower risk and severity of COVID-19…. Our findings are aligned with preliminary evidence showing that improving nutrition could help reduce the burden of infectious diseases,” the researchers wrote.

The study, “Diet quality and risk and severity of COVID-19: a prospective cohort study,” was published in BMJ. 

Past studies have linked metabolic conditions, including obesity, type 2 diabetes, and high blood pressure to a higher risk of severe COVID-19. Enough evidence shows that poor diets increase the risk of developing these metabolic conditions and that healthy plant-based diets including fruits, vegetables and wholegrains lower the risk. However, it is unknown whether diet also affects the risk and severity of COVI9. 

“Previous reports suggest that poor nutrition is a common feature among groups disproportionately affected by the pandemic, but data on the association between diet and COVID-19 risk and severity are lacking,” Jordi Merino, PhD, a research associate at the Diabetes Unit and Centre for Genomic Medicine at MGH and an instructor in medicine at Harvard Medical School, said in a Press Release

To bridge this knowledge gap, a team of scientists in the United Kingdom (UK) analysed data from 592,571 participants enrolled in the COVID-19 Symptom Study. Participants were resident in the UK and United States and were recruited from March 2020 and followed until December 2020. 

The participants provided information about their diet via a food frequency questionnaire containing 27 food items. The researchers quantified participants’ diet quality using the healthful Plant-Based Diet Index (hPDI) score, which awards points for healthy plant food groups such as fruits and vegetables and subtracts points for less healthy plant and animal food foods. 

During the follow-up, 31, 815 participants developed COVID-19. Compared to participants with a low diet quality score, those with a high diet quality score had a 9% lower risk of developing COVID-19 and a 41% lower risk of severe COVID-19. 

The researchers examined the data further to determine if mask-wearing contributed to the differences in risk scores between people consuming high- and low-quality diets. Compared to participants with low-quality diets, those with high-quality diets had a 12% lower risk of COVID-19.

“Although we cannot emphasise enough the importance of getting vaccinated and wearing a mask in crowded indoor settings, our study suggests that individuals can also potentially reduce their risk of getting COVID-19 or having poor outcomes by paying attention to their diet,” Andrew Chan, MD, MPH, a gastroenterologist, and chief of the clinical and translational epidemiology unit at MGH, said. 

Further analysis showed that socioeconomic status also contributed to COVID-19 risk, with socioeconomic deprivation increasing COVID-19 risk. 

“Our models estimate that nearly a third of COVID-19 cases would have been prevented if one of two exposures – diet or deprivation – were not present,” Merino said. 

Public health interventions that improve nutrition, metabolic health and other social determinants of health may also reduce the burden of COVID-19. 

“Our findings are a call to governments and stakeholders to prioritise healthy diets and wellbeing with impactful policies; otherwise we risk losing decades of economic progress and a substantial increase in health disparities,” Merino added. 

A limitation of the study is that it was an observational study, so the researchers cannot confirm that poor diets raise COVID risk or determine the pathways involved. 

“In conclusion, our data provide evidence that a healthy diet was associated with a lower risk of COVID-19 and sever COVID-19 even after accounting for other healthy behaviours, social determinants of health and virus transmission measures,” the authors wrote. 

What does this study mean for you? – A Nutritionist’s Perspective

First, it is crucial to understand that this study is observational, and therefore you can’t absolutely say that poor diets increase COVID-19 risk and severity. Second, this study is based on food frequency questionnaires which are inherently biased and do not necessarily depict a person’s diet. 

However, we know that healthy diets, including plenty of whole foods, can provide the vitamins, minerals, and plant compounds such as antioxidants that boost our immune system, making it easier to fight off infections such as COVID-19. 

Animal foods were classed as unhealthy based on the food scoring system the researchers used. All animal foods are not created equal, and evidence shows that eaten in the correct proportions and cooked correctly, they are sources of essential vitamins and minerals that may be challenging to get on an exclusive plant diet. 

You don’t need to cut out animal foods to lower your risk of COVID-19. The most important thing is to ensure you eat a wide variety of plant foods, with small to moderate quantities of animal foods. Exercise regularly, stay hydrated and get enough sleep. 

If you need help improving your diet, you can schedule a free 15-minute discovery call to learn how I can support you. 

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