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Nutrition and COVID-19

STUDENT CONTRIBUTOR: Michael Sheng | School of Nutrition, Ryerson University

September 24, 2020

We’re eyeballs deep in a pandemic. The numbers are on the rise, again, and any chance of a vaccine to help manage the spread is at least another four to six months away. While we wait, we can help protect ourselves by following proper hygiene and hand washing techniques, following social distancing protocols and making sure we are eating healthy, balanced meals full of nutrients that support our immune system.

With flu season upon us, it’s especially important to power up our immune system. While there is limited evidence supporting any one specific dietary approach minimizing the risk of contracting or curing COVID-19, it is known that a healthy, balanced, nutritious diet rich in whole foods that have essential vitamins and minerals feeds the immune system and improves its function.

“A vitamin is a substance that makes you ill if you don’t eat it.” ~ Albert Szent-Gyorgyi | Nobel Prize Winner: Physiology or Medicine


Viruses, like COVID-19, often weaken the immune system, making it harder to recover and stay healthy. In a time when public health is a priority, a focus on diet - the foods we eat every day - is a beneficial way to boost our immune system and reduce health risks.

Globally, 1 in 3 people suffer from micronutrient deficiencies. Eating processed, refined, packaged foods that are high in saturated or trans fats and added sugars typically lead to low levels of essential micronutrients (vitamins, minerals) and macronutrients (carbohydrates, protein, fat) being available or absorbed within the body, leaving it less equipped to fight off bacteria and viruses.


A common culprit for weakened immune systems is the western diet; a diet most Canadians enjoy. Common foods found in the western diet can lead to inflammation in the body, which can be made worse by viruses and infections, leading to long-term health problems. This diet tends to be high in saturated fats and is shown to weaken the immune system and contribute to chronic diseases like diabetes and heart disease. In some cases, it can make self-management of chronic disease more challenging; e.g., if you have diabetes, insulin needs may rise due to increased stress on the body from the flu. There is not enough evidence, yet, to fully understand the impact on insulin needs for someone with diabetes who is diagnosed with the coronavirus, but early research does show an increased risk to heart health and other long-term complications.

High levels of saturated fats in a diet can also weaken your adaptive immune system, making it harder for your body to defend against new, foreign viruses such as COVID-19. To lower saturated fat levels, try to stay away from red meats such as beef, lamb, and pork, as well as butter and whole-fat dairy products.


Think about choosing nutrient dense, whole foods and eating a variety of proteins, grains, fruits and vegetables like filling your car’s tank with gas. If you don’t put gas in your car, you’re not going anywhere. If you don’t put the kind of gas your car needs, it clogs up the system and might even break down. Healthy, balanced meals made up of whole foods provide fuel for the body, giving us energy and feeding our brain, nervous system and muscles so that our bodies can work for us to prevent infections, disease and poor health.

The Canada Food Guide recommends half your plate be made up of fruits and vegetables (2 handfuls), a quarter of your plate being made up of lean protein (the size of your palm, and a quarter of your plate being made up of whole grains and starches (the size of your fist). Water is recommended as the drink of choice; 6-8 cups per day. Enjoy milk - a good source of calcium and protein - as an alternative to water. If you are sensitive to lactose, there are many lactose-free, plant-based milk varieties available. Including variety in your meals is important to ensure you are enjoying what you eat and getting the full benefit of all nutrients available from different foods.


Vitamin E

Vitamin E is an antioxidant that helps protect your cells from inflammation and is important for our eyes. Studies have shown that Vitamin E deficiencies lead to weakened immune responses.

You can find vitamin E in many plant-based oils (e.g., sunflower oil), sunflower seeds, almonds and other nuts, mangoes, avocados, salmon, olives, blackberries, kiwi and more.

Vitamin C

Like vitamin E, vitamin C is an antioxidant, meaning it protects your cells from inflammation introduced into the body through toxins and pollutants. Vitamin C also helps maintain bone health. Make sure you enjoy a variety of fruits and vegetables and avoid smoking to keep up with your vitamin C needs.

You can get vitamin C from foods like oranges, tomatoes, kale, cauliflower, broccoli, cabbage, potatoes, kiwi, lemons, strawberries, brussel sprouts and spinach.

B Vitamins

There is some evidence that B vitamins (2, 6, 9 and 12) have the ability to enhance the function of immune cells.

Vitamin B2, a.k.a. riboflavin, boosts the immune system. According to Everyday Health, riboflavin helps your body break down and use the carbohydrates, fats, and proteins in your diet and helps metabolize food into energy and keeps your skin, the lining of your gut, and your blood cells healthy. Natural food sources like nuts, green vegetables, meat, and dairy products have riboflavin.

B6 is involved in more than 100 enzyme reactions in the body's cells and could help reduce the risk of heart disease. B6 is found in a variety of whole grains, fruits and plant-based foods like bananas, beans, brown rice, carrots, cheese, chicken, lentils, milk, salmon, spinach, sunflower seeds and whole-grain flour.

Vitamin B9, a.k.a. folate, is critical to fetal development and helps manage our mood. Folate and its synthetic form, folic acid, is important during pregnancy. Folate is found in green leafy vegetables, beans, peas, peanuts, and other legumes, and citrus fruits.

While most people get plenty of B vitamins through food, a deficiency in vitamin B12 is common in seniors, people with GI disorders and some who follow a vegan or vegetarian diet. Natural sources rich in vitamin B12 are dairy products, fish, meat, and — in particular — beef liver and clams. Breakfast cereals and nutritional yeast are fortified with B12.

Vitamin A

Vitamin A is also an antioxidant. Are you noticing the trend, yet? Antioxidants are good for you! Vitamin A is unique, though, because it plays a slightly different role in the immune system. Known as the anti-inflammation vitamin, it also helps in the development and regulation of the immune system. *Oral supplementation of vitamin A is not recommended, as new research shows that high levels of Vitamin A can actually weaken the immune system, making your immune system ‘forget’ past infections that your body has grown to defend against.

Foods rich in Vitamin A include carrots, broccoli, dairy, fish, hard-boiled eggs, organ meats, salmon, trout, cheeses and fortified cereals.

Vitamin D

Vitamin D, a.k.a. ‘the sunshine vitamin’, is a crucial vitamin for maintaining bone health, and is also shown to aid in the immune response for the flu, especially with people with pre-existing chronic illnesses. Vitamin D also has anti-inflammatory properties, as Vitamin D deficiencies have been linked to increased risk of respiratory diseases. For people who live in areas where the seasons change and find themselves inside for extended periods without exposure to sunlight, oral supplementation helps to meet recommended daily intakes. *Always speak to your doctor or registered dietitian before you start taking oral supplements.

Foods high in Vitamin D include salmon, herring, sardines and other fatty fish, cheese, egg yolks, mushrooms, soy products like tofu and milks, as well as fortified juices and cereals. In addition to getting Vitamin D from food sources, your body can also naturally synthesize Vitamin D with the help of some natural sunlight! So take advantage of your body’s natural abilities, and go out for a (socially-distanced) stroll in the sun!


Zinc is a mineral crucial in metabolism and growth, promotes immune functions and helps people resist infectious diseases; including diarrhea, pneumonia and malaria. Zinc is also needed for healthy pregnancies. A diet including foods with zinc may help to lower the incidence and reduce the duration of common cold.

Zinc can be found in red meats and poultry, shellfish, legumes, nuts and seeds, potatoes, green beans, eggs, cheese, milk, whole grains, oysters, beans, and dark chocolate.


If you don't get enough iron through the foods you eat, a deficiency could weaken the immune system. Iron can be found in both animal and plant-based sources, but the iron in meats is absorbed better by the body. Vitamin C helps the body absorb iron. Combining iron-rich foods with vitamin C can help boost your absorption. You can also improve your absorption of iron from foods by using cast-iron pots and pans to cook with, and avoiding tea or coffee with meals. Iron is necessary, but can be tricky because high levels of iron can actually work against you and suppress the immune system. Make sure to speak to your doctor or registered dietitian before taking any supplements.

Foods rich in iron include meat, poultry, fish, shellfish, legumes, nuts, seeds, cruciferous vegetables and dried fruit.

Omega-3 Fatty Acids

The strength of the immune system is also dependent on a sufficient supply of Omega-3, which plays an essential role in the regulation of inflammation. Omega 3 fats play a crucial role in the growth and proper functioning of the human body. Include foods that are rich in omega 3 in your diet and you won't need to buy expensive supplements.

Sources of Omega-3 include fatty fish like salmon or tuna, canola oil, chia seeds, ground flaxseed, nut butters, oatmeal, pumpkin seeds, tofu, brussel sprouts, avocado, shellfish, walnuts and fortified dairy and juices.

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It’s always best to look for what you need through whole foods. Some people, however, aren’t able to get all the necessary nutrients we need to meet recommended amounts due to dietary restrictions (e.g., allergies, intolerances or issues with malabsorption). In this case, taking a multivitamin or oral supplements can be beneficial to prevent deficiencies.

*IMPORTANT: speak to your doctor or a registered dietitian before taking supplements.


There is no diet guaranteed to cure or prevent to COVID-19, but there are many foods that can help strengthen the immune system and get a step ahead of things.

Try to limit processed and refined foods that are high in saturated fats, or enjoy them less often in smaller portions.

Enjoy foods that are high in antioxidants; such as zinc and vitamins A, C, D and E (examples listed above). Making a plan to get most of your nutrients through natural, whole food and/or plant-based sources should provide you all the nutrients you need.

Stay hydrated. Drink 6-8 cups of water every day. Some people have a hard time meeting the daily recommendations with plain water, but fluids in things like soups, coffee and tea count, too! Remember - variety is the spice of life!

Get moving. Health Canada recommends that people ages 1-4yrs should be active at any intensity for at least 180 minutes spread throughout the day. Ages 5-17yrs should be active for at least 60 minutes per day, participating in vigorous activity at least three times per week. Adults 18yrs+ should get active for an average of 150 minutes of physical activity per week in bouts of at least 10 minutes each time. Check out the Canadian Physical Activity Guidelines for more details and suggestions for how to get your body moving. *Always check-in with your doctor before increasing your physical activity or starting a new exercise program.

There is no vaccine or cure for COVID-19, yet, so please be sure to continue wearing your mask, washing your hands frequently and practicing physical distancing by keeping to your personal bubble and staying two meters apart from those outside your bubble.


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