Welcome back! We hope you are well, safe, and continuing to fit exercising into your daily routine.
This week’s blog focuses on food. In particular, we want to bust some of the myths and misinformation you might be seeing about food and nutrition and how it can prevent or treat COVID-19. In order to present the best and most up-to-date information on this subject we have invited Janice L. Thompson, Professor of Public Health Nutrition and Exercise at the University of Birmingham to be this week’s guest blog writer.
How what you eat affects your immune function
The foods we eat affect our ability to fight off infections and recover from illness, particularly foods containing certain vitamins and minerals. So eating foods that contain these nutrients can help your body deal with viruses and infections. In contrast, a lack (deficiency) of one or more of these nutrients makes it more likely we could get infected, and leads to more severe levels of illness and poorer recovery.
Nutrients and foods that support a healthy immune system
The good news is that these important nutrients are in a lot of commonly available foods.
This table shows you the nutrients that can help strengthen your immune system, and the foods that contain them.
|Nutrient||Food Sources||Role is supporting immune function|
|Vitamin A:||Animal-based: Liver (beef and chicken), full-fat milk, egg yolks, cheese
Plant-based: Dark green leafy vegetables(spinach, kale, rocket, Bok choy)-Orange-coloured fruits and vegetables (carrots, sweet potatoes, pumpkin, butternut squash, apricots, mango, cantaloupe melon)
|-Supports the health of the cells in our bodies-Helps support T-cells, which are a type of white blood cell that identifies viruses that enter our bodies|
|Vitamin C||Animal-based:None – only found in plant-based foods.
Plant-based:Citrus fruits (oranges, lemons, limes, grapefruit), sweet peppers (red, orange or yellow), broccoli, cauliflower, sweet potatoes, strawberries, green vegetables, tomatoes.
|-Helps our immune cells attack pathogens such as viruses-Helps clear out old immune cells from areas of infection-Helps maintain our skin, which acts as a barrier to infection|
|Vitamin E||Animal-based:None – only found in plant-based foods.
Plant-based:Vegetable oils (all types), avocado, peanuts, peanut butter, sunflower seeds, almonds, breakfast cereals with vitamin E added.
|Protects white blood cells and other parts of our immune system.|
|Vitamin D-Very limited amounts found in foods||Animal-based:Oily fish (salmon, mackerel, sardines, pilchards, anchovies), eggs, dairy products fortified with vitamin D
Plant-based:Breakfast cereals fortified with vitamin D
Other sources:We create our own Vitamin D when our skin is exposed to sunlight. People who do not go outside much or who do not expose their skin to the sun may need to take a supplement (a tablet or spray)
|-Helps our bodies to make some types of immune cells-Helps reduce inflammation that can result from infection and other causes|
|Zinc||Animal-based:Meat (all types), poultry, some shellfish (oysters, crab), cheese, yogurt
Plant-based:Nuts and seeds, whole-meal breakfasts cereals, whole-meal and seeded breads
|-Helps us to build various types of immune cells-Supports communication between immune cells to help fight infection|
|Selenium||Animal-based:Meat (all types), poultry, fish (tuna, halibut), shellfish, cheese
Plant-based:Nuts and seeds (mixed nuts, Brazil nuts, cashews, sunflower seeds) whole grains (whole-meal pasta, couscous)
|-Helps us to build various types of immune cells-Helps reduce the ability of viruses to multiply and mutate into more harmful strains|
|Iron||Animal-based:Meat (all types), poultry, fish (canned sardines), shellfish (cockles, mussels)
Plant-based:Breakfast cereals fortified with iron, beans, pulses, nuts and seeds, whole grains (quinoa), whole-meal breads, dried fruits
|-Helps maintain health and function of various immune cells-Excessive iron intake can damage immune cells and increase rate of infection|
|Copper||Animal-based:Meat, fish, shellfish
Plant-based:Whole-meal breads and breakfast cereals, rice, quinoa, pulses, avocado, dried fruits, nuts and seeds
|-Helps maintain health and function of various immune cells|
Can Nutritional Supplements protect against COVID-19?
There is some limited evidence that taking vitamin C supplements or zinc lozenges may reduce the length and/or severity of the common cold, but the common cold is caused by a different virus to COVID-19. To date there is no food or nutrient identified to prevent or treat COVID-19. Anyone who suggests there is is probably trying to sell you something – so beware!
As you can see from the table above, eating a wide range of foods means that most people should not need to take vitamin or mineral supplements. In fact, taking individual nutrient supplements can interfere with some medications, so check with your doctor if this is something you plan to do. Also, stick to the government recommended doses as taking too much of an individual supplement can be bad for your health.
However, there are some people who are not able to eat a good diet for some reason who may benefit from taking a multivitamin and mineral supplement. Keep in mind that there are no nutritional supplements that provide the range of nutrients present in the foods we eat. As such, getting nutrients from your food is always the best approach. But if you do feel you would benefit from taking a multivitamin and mineral supplement, check with your GP or other healthcare professional to make sure it is safe for you.
We hope this week’s blog has helped you to see how your diet can support your immune system and help you fight COVID-19 and other viruses.
Professor Janice L. Thompson
Dr Janet Withall, REACT Trial Manager, University of Bath
Dr Afroditi Stathi, REACT Chief Investigator, University of Birmingham
Dr Jolanthe de Koning, REACT Research Associate, University of Bath
Dr Pete Ladlow, UK Defence Medical Rehabilitation Centre