- Recent studies have shown that following a plant-based diet may reduce the risk and severity of COVID-19.
- Researchers said the connection is likely due to healthy gut bacteria that feed off plant foods and keep the immune system strong.
- Vaccinations along with mask wearing and social distancing remain the most effective tools in preventing COVID-19.
Many have suggested that certain diets can reduce the risk of COVID-19, including Sweetgreen CEO Jonathan Neman, who proposed controversial “health mandates” and taxes on processed foods and refined sugar as a solution to the pandemic.
Multiple studies have associated plant-based diets with lower risk and severity of COVID-19. But how reliable are these claims?
In one recent study published in Gut, researchers used a short-form food frequency questionnaire made up of 27 questions to capture data about the dietary habits of the participants. The diets were scored using a healthful plant-based diet index, a scoring system that ranks a wide range of foods based on healthiness.
The questionnaire leaves room for error because it relies on self-reported data rather than assessing what people actually ate, says Duane Mellor, RD, PhD, the lead for Nutrition and Evidence-Based Medicine at Aston Medical School.
“We have to be careful with plant-based diets and what we actually mean,” Mellor tells Get Meds Info.
As the food industry responds to the increasing demand for plant-based items, Mellor says, “plant-based” labels may be applied to foods that aren’t necessarily healthy. Consumers may end up buying processed plant foods over traditional fruits, vegetables, and legumes.
Mellor says the studies claiming that a plant-based diet can reduce COVID-19 risk are often not precise enough for a solid conclusion.
“We overcomplicate what we think about as a healthy diet,” he says, adding that basic foods like seeds, nuts, vegetables, and fruits that prevent a number of chronic diseases may keep the immune system less susceptible to COVID-19.
However, the main prevention tool for COVID-19, Mellor adds, is to mitigate exposure.
Can Diet Protect Against COVID-19?
“There are a lot of factors which underlie someone’s risk of developing COVID,” Andrew Chan, MD, MPH, professor of medicine at Harvard Medical School and a co-author of the study in Gut, tells Get Meds Info. “Coming into contact with the virus or being in contact with people who have COVID-19 are the strongest risk factors.”
But other factors, like dietary habits, may also predict the likelihood of someone getting an infection or developing a serious case of COVID-19, Chan explains.
“Diet is a risk factor for a lot of different conditions,” Chan says. “And many of those conditions have a common mechanism which is underlying states of inflammation or metabolic conditions that are clearly influenced by diet.”
Chan and his team monitored over 500,000 participants on their COVID-19 test results and symptoms along with their diet quality, controlling for factors like age, Body Mass Index, population density, and smoking status.
The study concluded that people with the highest diet quality were 10% less likely to contract COVID-19 40% less likely to fall severely ill from the infection than those who scored the lowest on diet quality.
However, researchers acknowledged that even though quality control procedures were in place, certain confounding factors could have influenced the results. For instance, those who follow healthy diets might be more likely to have better household conditions and hygiene or access to care.
What This Means For You
Vaccinations, mask-wearing, social distancing, and hand-washing remain the most powerful ways to reduce COVID-19 risk. A healthy plant-based diet is another tool that can potentially help reduce the risk of developing a severe case of COVID-19 if you encounter the virus.
While scientists don’t fully understand the connection between plant-based diets and COVID-19, gut microbes might play a role in the immune system.
“This community of microbes— called the microbiome—actually interact on a daily basis with the immune cells in our gut to keep our immune system primed against infection,” says Tim Spector, professor of genetic epidemiology and director of the TwinsUK Registry at Kings College, London, and co-author of the study.
Spector tells Get Meds Info that if we feed the microbiome with processed foods and chemicals instead of plants and fibers, we get “a much-reduced set of microbes” that can’t control the immune system properly. “That’s why it leads to more infections, food allergies, and problems like that,” he says.
Instead of going fully vegan or vegetarian, the study suggests maximizing the intake of plant foods in a balanced diet. A switch from processed foods to simple, plant-based foods could reduce harmful gut bacteria in a matter of weeks, Spector adds.
However, maintaining a plant-based diet may not be financially sustainable in some communities.
“The impact of diet was amplified by individual life situations, with people living in low-income neighborhoods and having the lowest quality diet being around 25% more at risk from COVID-19 than people in more affluent communities who were eating in the same way,” the researchers wrote in a press release.
Diet Does Not Replace Vaccines
Scientists still have a lot to learn about the roles diet and microbiome play in managing COVID-19 risks. These initial studies are just the start. Chan says more research could help doctors and dietitians prescribe individualized, long-term dietary plans based on microbiome.
But diet itself does not replace the need for other COVID-19 precautions like getting vaccinated or wearing a mask in indoor places.
“Diet is one aspect of risk that is important to take into account but it is not the only aspect,” Chan says. “We know for sure that the science demonstrates that vaccinations are critical, as is wearing a mask.”
Though maintaining a balanced diet is a potential factor to consider in COVID-19 prevention, Chan stresses that it’s “by no means a substitute” for important tools like vaccination, quarantine, hand washing, and mask wearing.
The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.