With temperatures cooling off and daylight hours reducing, it is time to start thinking about cold and flu season and what we can do to avoid getting sick. While it is not possible to eliminate the risk of getting a cold or the flu, taking steps to boost your immunity through diet may make your symptoms less severe if you do get infected.
Vitamins C, D, and E, selenium, zinc, and omega-3 fatty acids all play important roles in a healthy immune system. Not only does having adequate amounts of these nutrients decrease the risk of infection once exposed, but they also allow the immune system to function optimally when there is an infection. All of these nutrients help regulate and support the action of several types of cells responsible for mounting an immune reaction when needed. They also act as anti-inflammatories and antioxidants throughout the body allowing it to be in a better state to fight off infection.
Under normal circumstances, adequate amounts of most of these nutrients can be obtained by consuming a diet with a wide variety of fruits, vegetables, legumes, nuts, seeds, and fish. Since different foods contain different amounts of different nutrients, it is important to eat a variety of whole foods. These foods also contain other compounds, such as polyphenols and flavonoids, that can help support overall health.
Some of the best sources of these nutrients are listed below:
Vitamin C: citrus fruit, green peppers, broccoli, strawberries, tomatoes
Vitamin D: fortified dairy products, direct sun exposure, fatty fish
Vitamin E: nuts, seeds, vegetable oils
Zinc: whole grains, legumes, oysters, beef, poultry
Selenium: Fortified cereals, oysters, tuna, fish, poultry
Omega-3 fatty acids: fish, chia seeds, flax seeds, walnuts
When someone is at a greater risk of infection, such as during periods of acute stress, or in people with a low dietary intake, supplementation of Vitamin C, D and zinc may be beneficial to prevent infection. While the effect of consuming these supplements on the immune system may be modest for risk of infection and disease progression, taking them in certain situations may be beneficial. It is a relatively cheap and low-risk option to potentially avoid a cold or decrease the severity of symptoms as long as total intake is below the
tolerable upper intake levels issued by the Food and Nutrition Board. However, you should consult your doctor or a registered dietitian before taking any supplements to determine if they are appropriate for you.
References
Abioye, A. I., Bromage, S., & Fawzi, W. (2021). Effect of micronutrient supplements on influenza and other respiratory tract infections among adults: A systematic review and meta-analysis. BMJ Global Health, 6(1), e003176.
https://doi.org/10.1136/bmjgh-2020-003176
Barrea, L., Muscogiuri, G., Frias-Toral, E., Laudisio, D., Pugliese, G., Castellucci, B.,
Garcia-Velasquez, E., Savastano, S., & Colao, A. (2021). Nutrition and immune system: From the Mediterranean diet to dietary supplementary through the microbiota. Critical Reviews in Food Science and Nutrition, 61(18), 3066–3090.
Carr, A. C., & Maggini, S. (2017). Vitamin C and Immune Function. Nutrients, 9(11), 1211.