Published 15th September 2021

COVID-19: How can nutrition keep me healthy?

Research suggests that people who eat a healthy diet rich in plant-based foods are less likely to get COVID-19. Eating this way can also help you recover if you have the virus.

Scientists from the ZOE COVID Study, the largest of its kind, have found that people who ate a high-quality diet, rich in plant-based foods, were 10% less likely to get COVID-19 and 40% less likely to get severe COVID-19 requiring treatment in the hospital. 

In this article, you can discover what the latest research says about the link between food and COVID-19, find out what foods to eat and to avoid, and what to eat if you do have COVID-19.

Lower COVID-19 risk with plant-based diets

So far, only a handful of studies have looked at the food that people eat and how likely they are to get COVID-19. There isn’t one particular food or one type of diet that can definitely prevent you from catching this coronavirus. 

In the largest study to date, scientists at ZOE, Harvard Medical School, and King’s College London looked at the diet of nearly 600,000 study contributors in the United States and the United Kingdom. 

They found a link between what people ate and whether they developed COVID-19. The key factor was diet quality, which is a way to score how healthy the food is that someone eats. 

People who ate the healthiest diet were 10% less likely to report having COVID-19 compared with those who had the unhealthiest diet. They were also 40% less likely to have severe COVID-19 that required treatment in the hospital.

The healthiest diet included many plant-based foods, such as fruits, vegetables, and whole grains, but also oily fish and fermented foods that are good for gut health. These foods are important for your immune system, which fights off infections.

Smaller studies have also found links between greater vegetable and coffee consumption and being less likely to have COVID-19, as well as links between eating plant-based or pescatarian diets and being less likely to have moderate to severe COVID-19. 

Best foods to eat

There is more and more evidence that following a healthy diet that includes plenty of plant-based foods, like fruit and vegetables, can help reduce people's likelihood of getting COVID-19, particularly severe COVID-19. 

Keep ultra-processed foods, refined grains, and sweetened drinks to a minimum, and aim for a varied diet that includes a range of foods from the following groups:

1. Vegetables

Vegetables are full of fiber, minerals, and vitamins, which support your immune system and help you fight off diseases. 

You can incorporate vegetables into your diet in many ways. Aim for a variety throughout the week, which can include both fresh and frozen veggies. You can also eat canned vegetables, but look for brands that are low in added sugar and salt.

Vegetables can take center stage as the main component of your meal; think soups, roasted cauliflower, or a simple corn on the cob. Another way to incorporate more veggies into your meals is by chopping them finely and mixing them in with your other ingredients. 

Check out these ways to include more vegetables in your diet. 

2. Fruit

Whole fruit is naturally sweet and has many nutrients that are good for your health, including fiber and vitamins.  

Try starting your day with chopped fruit in your cereal or with yogurt, and reach for an apple or a banana as a snack between meals.

Look for seasonal fruits that are available fresh in your area or opt for frozen or canned fruit, looking out for brands that are low in added sugar and salt. 

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3. Whole grains

Whole grains, including brown rice and wholemeal pasta, contain all three parts of the grain: the bran, endosperm, and germ. This is in contrast to refined grains, which are processed to remove the bran and the germ.

There are plenty of nutrients in the bran and the germ, such as fiber, healthy fats, minerals, and vitamins, which you can only get by eating the whole grain. 

As well as wholemeal pasta and brown rice, there are plenty of other whole grain options:

  • buckwheat

  • bulgur wheat

  • corn

  • millet

  • quinoa

  • rye

  • oats

  • spelt

  • wild rice

Try swapping some regular all-purpose flour for spelt flour during baking. And substitute some white rice with brown or wild rice while cooking to gradually up your whole grain intake. 

4. Oily fish

Oily fish is high in omega-3 fats, which are essential for our health. Aside from these healthy fats, fish also has a host of other important nutrients, including iodine, iron, selenium, vitamin B2, vitamin D, and zinc. 

Some of the healthiest fish to eat are farmed trout, sardines, anchovies, and herring. 

Shallow frying, steaming, stewing, and roasting are all good ways to prepare these types of fish, but you could also try canned, pickled, or fermented fish.

5. Nuts and seeds

Nuts and seeds contain healthy fats and other nutrients, such as antioxidants, fiber, minerals, and vitamins. 

Almonds, Brazil nuts, cashews, hazelnuts, macadamia nuts, peanuts, pistachios, and walnuts all make convenient snacks and are easy to bring on the go.

Try them chopped at breakfast or in a salad at lunch, but limit the amount of roasted or salted nuts you eat. 

6. Legumes

Legumes — such as chickpeas, beans, lentils, and peas — are a good source of fiber and protein. 

Scientists have found that incorporating legumes into the diet can lower a person’s risk of developing chronic conditions such as heart disease and type 2 diabetes.

Try swapping some of the meat in bolognese sauce for lentils or adding chickpeas to salads and soups.

Canned versions are good if you don’t have the time to cook legumes from scratch, but look for versions that are low in salt and sugar. 

7. Fermented foods

Fermented foods are great for your gut. They increase the quantity and diversity of the trillions of microbes that reside here and form your gut microbiome

A healthy gut microbiome supports your immune system, helping you fight off infections, including COVID-19. 

Fermented foods include:

  • kefir

  • kimchi 

  • sauerkraut

  • yogurt

For more tips, check out this article on how to improve diet quality and protect against COVID-19 by the ZOE COVID Study team.

Foods to avoid

A diet that includes a lot of lower quality, unhealthy foods leaves less space for healthier choices. Try to cut down on these types of foods and swap them for healthier options that support your immune system and lower your chances of getting COVID-19. 

1. Ultra-processed foods

People in the U.S. and the U.K. consume nearly 60% of their energy intake each day in the form of ultra-processed foods. 

These foods are highly processed and often contain added sugar, salt, fats, and additives. They are designed to be extra tasty but contain few valuable nutrients. 

Scientists have found that people who eat a lot of ultra-processed foods are more likely to have excess weight and chronic health conditions like asthma, cancer, depression, heart disease, and type 2 diabetes. 

Ultra-processed foods include store-bought bread, sweetened breakfast cereals, chocolate, and microwave meals.

Look for healthier alternatives, including wholemeal homemade or artisanal bread and plain breakfast cereal, such as steel-cut oats. Reach for vegetables, fruits, and nuts when you’re in the mood for a snack. 

2. Refined grains

Refined grains, like white rice, white pasta, and all-purpose flour, don’t contain as many nutrients or fiber as their whole grain cousins.

Try swapping refined grains for those whole grain options that we list above.

3. Sweetened beverages

Sugar-sweetened drinks, including soda, iced tea, energy drinks, and frappuccinos, contain a lot of sugar and essentially no nutritional value. 

Regularly drinking these is linked to a higher risk of developing chronic conditions like heart disease, gout, and type 2 diabetes. 

Sugar-free drinks, such as diet soda, may not have the calorie impact of sugar-sweetened drinks, but some scientists are concerned about the effects of artificial sweeteners on our health. 

Early data from ZOE’s PREDICT Program, the largest nutritional study of its kind, shows artificial sweeteners can lead to a rise in blood sugar in some people. 

Water is by far the healthiest option. The World Health Organisation (WHO) recommend staying hydrated by drinking plenty of water as part of a healthy diet during the COVID-19 pandemic. 

What to eat if you have COVID-19

If you have COVID-19, it’s important that you stay hydrated and eat plenty of nutritious and high-energy food

Your body loses a lot of water while fighting off an infection, particularly if you have a fever or if you experience diarrhea and vomiting. It’s important that you maintain your fluid levels if you have COVID-19. 

Water is the best option, but hot drinks and those that are high in calories, such as smoothies and full-fat milk drinks, are also good choices. 

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You may not feel like eating much while you are sick. But your body needs energy to help you recover. Not eating enough can increase your risk of malnutrition, which will make it harder for your body to fight off infections and get better. 

Eating smaller meals or snacks throughout the day may be easier than eating big meals. 

Aim for foods that are high in protein, such as:

  • full-fat dairy or plant-based alternatives

  • oily fish

  • eggs

  • tofu

  • legumes

  • nuts and seeds

Summary

Looking after your body by eating healthy foods can lower your chances of getting COVID-19, particularly severe COVID-19. It can also help you recover if you have COVID-19.

Vegetables, fruit, whole grains, oily fish, nuts and seeds, legumes, and fermented foods are all healthy options to support your immune system and your overall health. 

ZOE’s research shows that eating these foods is important for your gut microbiome, which, in turn, contributes to your immune system and helps you fight off infections, including COVID-19. 

Sources

Common questions about fruits and vegetables. (n.d.).

https://www.hsph.harvard.edu/nutritionsource/common-questions-fruits-vegetables/

COVID-19/Coronavirus — Advice for the general public (n.d.).

https://www.bda.uk.com/resource/covid-19-corona-virus-advice-for-the-general-public.html

Dietary behaviors and incident COVID-19 in the UK Biobank. Nutrients. (2021).

https://www.mdpi.com/2072-6643/13/6/2114/htm

Diet quality and risk and severity of COVID-19: a prospective cohort study. Gut. (2021). 

https://gut.bmj.com/content/early/2021/09/06/gutjnl-2021-325353

#HealthyatHome: Healthy diet. (n.d.).

https://www.who.int/campaigns/connecting-the-world-to-combat-coronavirus/healthyathome/healthyathome---healthy-diet

Legumes and pulses. (n.d.).

https://www.hsph.harvard.edu/nutritionsource/legumes-pulses/

Plant-based diets, pescatarian diets and COVID-19 severity: a population-based case–control study in six countries. BMJ Nutrition, Prevention & Health. (2021). 

https://nutrition.bmj.com/content/4/1/257

Sugary drinks. (n.d.). 

https://www.hsph.harvard.edu/nutritionsource/healthy-drinks/sugary-drinks/

Ultra-processed foods and added sugars in the US diet: evidence from a nationally representative cross-sectional study. BMJ Open. (2015).

https://bmjopen.bmj.com/content/6/3/e009892

Ultra-processed foods and excessive free sugar intake in the UK: a nationally representative cross-sectional study. BMJ Open. (2018).

https://bmjopen.bmj.com/content/9/10/e027546

Whole grains. (n.d.).

https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/whole-grains/

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