New research suggests that eating a plant-rich diet helps protect against COVID-19

Over the last year, you've probably done countless things to protect yourself and your loved ones from COVID-19.

But have you ever considered the role your diet might play in reducing your risk?

Back in the Autumn of 2020, the ZOE COVID Study team asked contributors to complete a detailed diet questionnaire about the food they were eating before and during the pandemic. Over 600,000 contributors took part in this research, making it the largest study of its kind.

Together with leading researchers at Harvard Medical School and King’s College London, our team analyzed this diet data and mapped it against COVID symptoms and positive tests reported by contributors.

For the first time our new research, published in the BMJ, suggests that eating a diet rich in high-quality plant foods can protect against COVID-19.

You can learn more about this study from the researchers themselves in the webinar below.

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Key findings from this research

• Researchers analyzed data from nearly 600,000 ZOE COVID Study app contributors, making it the largest study in this space.
• People with the highest quality diet were around 10% less likely to develop COVID-19 than those with the lowest quality diet, and 40% less likely to become severely ill.
• This is the first longitudinal study of diet and COVID-19 and the first to show that a healthy diet is associated with a lower risk of developing COVID-19.
• The scale of the study meant researchers were able to adjust for multiple confounding factors, like socioeconomic status and weight, which can be a challenge for smaller studies.
• The effect of diet on COVID-19 was independent of other known risk factors, including age, weight, race/ethnicity, and underlying health conditions, but was amplified by social inequality.

How did we measure diet quality?

Rather than looking at specific foods or nutrients, this study focused on diet quality and wider dietary patterns, which more accurately reflect how we eat.

Scientists used a scientifically validated Diet Quality Score (DQS) to understand the overall nutritional value of contributors' typical diets.

Generally speaking, diets with high-quality scores contain more plant-based foods such as fruits, vegetables, and whole grains, oily fish, and fewer processed foods and refined carbohydrates.

Our research into the gut microbiome also suggests that people who eat a higher-quality diet generally have a healthier and more diverse gut microbiome, and better markers of health, including lower levels of inflammation and body fat, and healthier blood fat and sugar responses.

How is diet linked to COVID-19 risk?

We discovered that people who ate the highest quality diet were around 10% less likely to develop COVID-19 than those with the lowest quality diet. Not only that, but they were also 40% less likely to become severely ill if they developed COVID-19

Importantly, this relationship between diet quality and COVID-19 risk was still there after accounting for age, body mass index (BMI), ethnicity, smoking, physical activity, underlying health conditions, mask-wearing habits, and population density.

While we still don’t know exactly how diet helps protect against COVID-19, inflammation may play an important role. Diet quality is a known risk factor for many conditions that are known to have an inflammatory basis. And this may also hold true for COVID-19, a virus that is known to trigger a severe inflammatory response.

Who could benefit most from eating a better quality diet?

For the first time, these findings show that a healthier diet can cut the chances of catching COVID-19, especially for people living in more deprived areas.

People living in low-income neighborhoods with the lowest quality diet were around 25% more at risk from COVID-19 than people in more affluent communities with similar diet quality.

Based on these results, we’ve calculated that nearly a quarter of COVID-19 cases could have been prevented if these differences in diet quality and wealth had not existed.

Access to healthier food is important to everyone in society, but these findings tell us that helping those living in poorer areas to eat more healthily could have the biggest public health benefits.

How can I improve my diet to help protect against COVID-19?

At ZOE we’re using the latest data science to unpick the complex connections between diet and health.

This study clearly shows that eating a diet rich in high-quality, plant foods is associated with a lower risk from COVID-19. We also know that eating more plants is great for your gut microbiome and overall metabolic health.

Taking steps to improve the quality of your diet is a good idea, not just during the pandemic but for your overall health. If you aren't quite sure where to start, check out:

• Our ten top tips for getting more plants on your plate
• This blog post on 7 ways to improve diet quality and protect against COVID-19
• Professor Tim Spector's top 5 tips for a healthier gut microbiome

Beyond this, there really is no one-size-fits-all approach to nutrition that works for everyone. After all, our research has shown that your gut microbiome and responses to food are unique. 

At ZOE, we believe that understanding how your body works is key to picking the right foods for you. 

With our at-home test, you can discover your blood fat and blood sugar responses to any food or meal, your unique mix of gut microbes, and receive personalized advice on the best foods to eat to support your health.

Want to learn more about what ZOE can do for you? Take our free evaluation and get started on your journey to better health today.