A team of researchers from King's College London, Harvard Medical School and the health science company ZOE analyzed data from more than 590,000 people from the United States and the United Kingdom who answered a survey about the foods they ate during February 2020 using the ZOE COVID Symptom Study application.
The application, which has been used to track COVID-19 outbreaks in the U.K., allows users to take note of any symptoms they develop in case of infection and log when they have had a positive polymerase chain reaction (PCR) test. By early December 2020, 19 percent of those 590,000 users contracted COVID-19 based on symptoms and positive PCR test results reported in the application.
For the first time, we've been able to show that a healthier diet can cut the chances of contracting COVID-19, said study co-author Sarah Berry, a senior lecturer at King's College London.
Scientists now know that diet-related health conditions, such as diabetes and heart disease, increase the risk of becoming severely ill with COVID-19. However, it's not clear how people's eating habits affect their risk of becoming infected with the virus independently of diet-related health conditions.
To shed light on the subject, the researchers analyzed data from 592,571 people from the U.S. and the U.K. who completed a survey about their eating habits using ZOE's "COVID Symptom Study" application. They designed the survey to look at broad dietary patterns, which are reflective of how people actually eat, instead of specific foods and nutrients.
The survey also produced a diet quality score reflective of the merit of each person's diet. Diets with high scores were found to contain more plant-based foods, such as fruits, vegetables, whole grains and nuts. People with these diets ate two pieces of fruit a day and three different vegetables. They also ate around 200 grams (g) of oily fish, such as salmon and sardines, every week and kept processed foods and refined grains to a minimum.
Diets with high quality scores were also linked to a healthier and more diverse gut microbiome. They were associated with various favorable health outcomes as well, including reduced inflammation and healthier blood lipid and glucose levels. The researchers referred to these high-scoring diets as "gut-friendly" diets.
People who eat high-quality diets have healthy microbes in their guts, said study co-author Tim Spector, one of the co-founders of ZOE. Having healthy gut microbes is linked to better health.
On the other hand, diets with low quality scores were found to be high in ultra-processed foods and low in plant-based foods. People with these diets often had no more than two pieces of fruit over the course of a week. They also went some days without eating any vegetables and oily fish. They also ate more fatty and sugary processed foods.
The researchers found that there were 72 cases of COVID-19 for every 10,000 person-months among users with high-scoring diets. On the other hand, there were 95 cases of COVID-19 for every 10,000 person-months among users with low-scoring diets.
Overall, they found that people with high-scoring diets were 10 percent less likely to contract COVID-19 and 40 percent less likely to become severely ill with the disease than people with low-scoring diets. Given these results, the researchers estimated that nearly a quarter of COVID-19 cases within the cohort could have been prevented if they ate a healthier diet.
The researchers said their findings concur with those of a recent comparative risk assessment study, which suggested that a 10 percent reduction in the prevalence of diet-related health conditions, such as Type 2 diabetes and obesity, would have prevented approximately 11 percent of COVID-19 hospitalizations among American adults since November 2020.
Given their findings, the researchers concluded that eating a healthy diet is associated with a lower risk of COVID-19 and severe COVID-19 infection. As such, the quality of one's diet may have a direct influence on COVID-19 susceptibility and progression.
But there is no need to go vegan to reap the benefits of healthy eating, said Spector. Nonetheless, eating a more plant-based diet could potentially reduce the risk of contracting COVID-19 by improving the immune system. (Related: The impact of lifestyle behaviors on a person’s immune system.)
Go to Fresh.news to learn more about the health benefits of eating plant-based foods.