Can a healthy diet protect you against COVID-19?

June 24, 2021

In our latest expert webinar, our ZOE COVID Study lead, Professor Tim Spector, was joined by Dr Sarah Berry, a reader at King’s College London and the lead nutritional scientist at ZOE, Professor Andrew Chan from Harvard Medical School, and Emily Leeming, a registered dietician and a nutrition research consultant for ZOE. They shared our latest findings about how your diet affects your COVID risk and how you can use food to protect yourself during the pandemic.


Investigating the link between COVID and diet 

Over the course of the pandemic, several factors have emerged that are linked to an increased risk from COVID-19, including age, body mass index (BMI), ethnicity and underlying health conditions. But so far, few studies have looked at the impact of what we eat. 

Although most of you will know ZOE because of our COVID Study app, before the pandemic we were focused on nutritional research. Over the past year, we’ve found ourselves uniquely placed to investigate the links between diet and COVID-19

That’s why several months ago, we asked our app contributors to complete surveys about eating habits pre and post-pandemic. Around 1.1 million people responded to the survey, making it the world’s largest dietary database of its kind. 

“Based on their responses to the survey, we analysed whether people had a poor, moderate, or high-quality diet. And then we looked at how the quality of their diet was associated with their risk of catching COVID and the severity of their COVID symptoms,” explains Sarah. 

What have we learned about diet and COVID risk?

“We found that people with the highest quality diet were less likely to catch COVID-19 compared with those that had the worst quality diet, and impressively they were significantly less likely to get severe COVID-19 disease and go to the hospital,” says Andy. 

“We were also able to show that the relationship between COVID-19 and diet was independent of other risk factors for COVID-19, including your age, your weight, your race, ethnicity, or other underlying health conditions,” he says. 

However, we found that the impact of a poor diet was more pronounced in low-income communities, suggesting that food may contribute to the health disparities we have seen during the pandemic.

“It shows that when we are trying to alleviate disparities in health outcomes, we should be thinking about how we can improve people's diet, particularly in areas that are socioeconomically deprived,” says Tim. 

You can read more about the findings of our research  a preprint of our on medRvix


What do we mean by diet quality?

“Diet quality is a spectrum. If we say you have a high-quality diet, usually we mean you have a diet that is diverse and well balanced, which provides you with enough energy and nutrients to live an active, fulfilled life,” says Emily. 

High-quality diets usually include lots of plant-based foods, including fruits, vegetables and whole grains, along with foods that nourish the microbes that live in your gut and support your immune system.

“On the other end of the spectrum, if you have a low-quality diet, typically we’re thinking of foods that are associated with poorer health outcomes, for example, ultra-processed foods,” explains Emily.

Examples of ultra-processed foods include things like packaged bread, breakfast cereals, chocolate and soft drinks. Unfortunately, much of the food we eat in the UK and US are ultra-processed, which may partially explain why we have been hit so hard by the pandemic compared with some other countries. 

“One of the big problems with food processing is that you're losing an essential component that confers health benefits to food - its structure. When we remove that structure, people tend to eat more calories at a given sitting. It also removes many of the beneficial compounds that are in foods that have favourable health effects,” explains Sarah.  

How can you improve the quality of your diet?

While there are several risk factors for COVID-19 that we can’t alter, we can change what we eat

Recent results from our landmark PREDICT nutrition study show that eating a plant-rich, ‘gut friendly’ diet is linked to a more diverse gut microbiome and better markers of health. Now these latest findings suggest that paying attention to the food on your plate could also play a part in helping you stay healthy during the pandemic.

However, Sarah warns people away from focusing on specific foods or nutrients, such as fat, carbohydrates or specific vitamins, and instead looking at the bigger picture of overall diet quality. 

“We're starting to understand that the food we eat has a complex structure that has a big effect on modulating how nutrients impact our health. So we need to be thinking about the foods we're eating and our overall dietary patterns, not single nutrients,” says Sarah.

She recommends increasing your intake of plant-based foods like legumes, whole grains, fruits, vegetables, nuts and seeds, and cutting down on ultra-processed foods. You could also include oily fish, which contain omega-3 fats that support immune function and heart health.

This high-quality diet has plenty of fibre to support your microbiome, but if you want to go the extra mile, you could add fermented foods like yoghurt or kefir, which contain beneficial probiotic bacteria that support gut health.

For more tips on improving your diet and gut health, check out our nutrition blog.

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