A study based on self-reported app data showed that people who eat a high quality, gut friendly diet are less likely to develop COVID-19 or become severely ill. Those eating poorer quality diets are more at risk, especially if they live in a more socioeconomically deprived area.
The study, presented in GUT, analysed data from almost 600 000 ZOE COVID Study app contributors. Participants completed a survey about the food they ate before the pandemic, in February 2020, making it the largest study in this space. 19% of these contributors contracted COVID-19.
People with the highest quality diet were around 10% less likely to develop COVID than those with the lowest quality diet, and 40% less likely to fall severely ill.
This is the first longitudinal study of diet and COVID and the first to show that a healthy diet cuts the chances of developing the disease in the first place.
Instead of looking at specific foods, the survey aimed to broadly capture people’s diets. A ‘diet quality score’ reflected the overall merit of each person’s diet. Diets with high quality scores were found to contain plant-based foods such as fruits, vegetables and whole grains, as well as oily fish, less processed foods and refined carbohydrates. A low diet quality score is associated with diets high in ultra processed foods and low amounts of plant based foods.
The researchers found that people who ate the highest quality diet were around 10% less likely to develop COVID-19 than those with the least nutritious diet and 40% less likely to become severely ill if they developed COVID.
The link between diet quality and COVID risk persisted after accounting for all potential confounding factors such as age and BMI. Mask-wearing habits and population density were also considered.
The effect of diet was amplified by individual life situations, with people living in low-income neighbourhoods with the lowest quality diet being around 25% more at risk from COVID than people in more affluent communities eating the same kind of diet.
Based on these results, the researchers estimate that nearly a quarter of COVID cases could have been prevented if these differences in diet quality and socioeconomic status had not existed. The study also showed that improved access to better food is an important public health consideration.
Dr Sarah Berry, study co-lead and Reader in nutritional sciences at the School of Life Course Sciences said: “For the first time we’ve been able to show that a healthier diet can cut the chances of developing COVID, especially for people living in the more deprived areas. Access to healthier food is important to everyone in society, but our findings tell us that helping those living in more deprived areas to eat more healthily could have the biggest public health benefits.”
Professor Tim Spector, professor of genetic epidemiology at the School of Life Course Sciences, said: “These findings chime with recent results from our landmark PREDICT study, showing that people who eat higher quality diets (with low levels of ultra-processed foods) have a healthier collection of microbes in their guts, which is linked to better health. You don’t have to go vegan, but getting more diverse plants on your plate is a great way to boost the health of your gut microbiome, improve your immunity and overall health, and potentially reduce your risk from COVID.”
Source: Kings College London