The study was published in the journal “Gut”.

The beneficial effects of diet on the risk of COVID-19 seemed particularly relevant in people living in areas of high socio-economic deprivation.

Although metabolic conditions such as obesity and type 2 diabetes have been linked to an increased risk of COVID-19, as well as an increased risk of developing severe symptoms once infected, the impact of diet about these risks is unknown.

“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 the risk and severity of COVID-19 is lacking,” said senior author Jordi Merino, PhD, associate researcher in the Diabetes Unit and Center for Genomic Medicine at the MGH and professor of medicine at Harvard Medical School.

For the study, Merino and colleagues looked at data from 592,571 participants in the smartphone-based COVID-19 symptom study. The participants lived in the UK and the US, and they were recruited from March 24, 2020 and tracked until December 2, 2020.

At the start of the study, participants completed a questionnaire about their eating habits before the pandemic. The quality of the diet was assessed using a healthy plant-based diet score that emphasizes healthy plant foods such as fruits and vegetables.

During follow-up, 31,831 participants developed COVID-19. Compared to individuals in the lowest quartile of the diet score, those in the highest quartile had a 9% lower risk of developing COVID-19 and a 41% lower risk of developing severe COVID-19.

“These results were consistent across a range of sensitivity analyzes taking into account other healthy behaviors, social determinants of health, and rates of transmission of the virus in the community,” Merino said.

“While we cannot stress enough the importance of getting vaccinated and wearing a mask in crowded indoor environments, our study suggests that individuals can also potentially reduce their risk of contracting COVID-19 or having perform poorly by paying attention to their diet, ”said co-lead author Andrew Chan, MD, MPH, gastroenterologist and head of the Clinical and Translational Epidemiology Unit at the MGH.

The researchers also found a synergistic relationship between a poor diet and increased socio-economic deprivation with the risk of COVID-19 which was greater than the sum of the risks associated with each factor alone.

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

The results also suggest that public health strategies that improve access to healthy food and address the social determinants of health may help reduce the burden of the COVID-19 pandemic.

“Our results are a call to governments and stakeholders to prioritize healthy diets and well-being with impactful policies, otherwise we risk losing decades of economic progress and a substantial increase in disparities. health matters, ”Merino said.

The study was co-led by researchers at Kings College London. Co-authors include Amit D Joshi, Long H Nguyen, Emily R Leeming, Mohsen Mazidi, David A Drew, Rachel Gibson, Mark S Graham, Chun-Han Lo, Joan Capdevila, Benjamin Murray, Christina Hu, Somesh Selvachandran, Alexander Hammers , Shilpa N Bhupathiraju, Shreela V Sharma, Carole Sudre, Christina M Astley, Jorge E Chavarro, Sohee Kwon, Wenjie Ma, Cristina Menni, Walter C Willett, Sebastien Ourselin, Claire J Steves, Jonathan Wolf, Paul W Franks, Timothy D Spector , Sarah Berry and Andrew T Chan.

Funding for the study was provided by the National Institutes of Health, the National Institute for Health Research, the UK Medical Research Council / Engineering and Physical Sciences Research Council, the Wellcome Trust, the Massachusetts Consortium on Pathogen Readiness, the American Gastroenterological Association, the American Diabetes Association, the Alzheimer Society, and Zoe Ltd.