Supporting your immune system during COVID-19

Your news feed may have been flooded with information on weird and wonderful ways to “boost” your immune system during the COVID-19 pandemic, from loading up on citrus fruit to consuming probiotic-filled yoghurt. However, while certain aspects of the system require these vitamins and minerals to function normally, there is no substantial data to support the assertion that these strategies will supercharge immunity. 

On a brighter note, there are some evidence-backed ways to maintain an optimally functioning immune system. These include a well-balanced diet, regular exercise, keeping stress levels to a minimum, adequate sleep, and hydration. While these tips are not guaranteed to protect you from contracting COVID-19, they can significantly reduce your risk of severe infection and hospitalisation. 

Proper Nutrition 

Your diet is at the forefront of optimal health, and functions as a vital component helping to protect against disease and infection. The gut is a key site of immune activity and the assembly of antimicrobial factors, so it may not be so surprising that what you eat plays a crucial role in influencing your immune system.3 When your intake of vital nutrients is inadequate, the production and functioning of immune cells and antibodies are suppressed, resulting in an increased risk of severe infection. 

Experts agree that a high-fibre, predominantly plant-based diet with minimal processed foods is one of the best diets to have. It is suggested to opt for a high intake of fruits and vegetables, whole grains, legumes, healthy fats, and lean protein – most commonly known as the Mediterranean diet. Fruits and vegetables, which should comprise half of a meal, are a fantastic source of antioxidants and nutrients such as beta-carotene, vitamin C, E, and B6, all of which support the growth of beneficial gut microbes and stimulate immune cell activity.1  

A diet high in protein, sugar, or food additives may disrupt the balance of certain gut microbes. To help restore this balance and support your immune system, experts suggest consuming probiotics and prebiotics. 

  • Probiotic foods – such as kefir, yoghurt and tempeh – consist of beneficial bacteria that help stimulate the immune response against pathogens. 
  • Prebiotics – found in onions, garlic and asparagus, amongst other foods – are filled with fibre and molecules that support the maintenance and growth of beneficial bacteria in the microbiota.4  

Keep physically active

Exercise has many benefits, and supporting an optimal immune system is one of them. Regular physical activity decreases inflammation, increases the production of anti-inflammatory cytokines (cells that aid immune cell recruitment), and improves the circulation of blood and lymphocytes (white blood cells). These effects have been shown to lower the incidence and intensity of symptoms of viral infections like COVID-19.6 

Research has indicated that 30 minutes of daily, moderate exercise helps stimulate your immunity. In fact, overdoing exercise in the form of heavy, long-term physical activity, such as marathon running or intense strength training, could do more harm than good.7 Moderate aerobic exercise is most recommended, such as daily walks, cycling a few times a week, or going to the gym every 2-3 days.

Reduce stress levels 

Stress is a factor that can have detrimental effects on physical and mental health, and it is often the most difficult thing to control. Stress stimulates the production of cortisol, a hormone that can suppress the function of your immune system in protecting against pathogens. It does this by impairing the communication between immune cells and the production of lymphocytes (white blood cells) and natural killer cells.5 These are critical immune cells that help to fight off viruses. 

Tip! Finding a strategy that minimises stress levels is unique to each individual, so make sure you find something that suits you and your lifestyle. This may be exercise, meditation, a hobby, or staying connected with friends and family. Additionally, practising mindful breathing exercises throughout the day can help too. 

Controlling your stress levels can also impact the quality and duration of your sleep. 

Don’t compromise on sleep 

Sleep is a fundamental aspect of optimal health and the functioning of the immune system. Researchers have shown that, during sleep, our immune system releases protective proteins, known as cytokines, as well as infection-fighting antibodies and immune cells.8 However, when we don’t get adequate sleep, the production of these cells decreases.  

Similarly to how sleep improves brain learning and memory consolidation, sleep may also strengthen immunological memory.9 Although the precise mechanism is still unknown, it is hypothesised that the immune system can quickly respond to a future pathogen by recalling how it previously reacted to the same pathogen. 

It is recommended that adults get at least 7 hours of sleep, teenagers aim for 8-10 hours, and younger children get 11-13 hours in a day. Less than 7 hours regularly creates a fight-or-flight state: a state characterised by high levels of stress hormones and the production of adrenaline.10 

Less alcohol, more water

A regular, high intake of alcohol is associated with reduced immune function and  various other detrimental health impacts. When you drink a lot of alcohol, your body consumes a lot of energy in detoxifying your system, rather than maintaining normal immunological functions to fight infection.11 Therefore, it is beneficial to try and reduce alcohol consumption as much as possible. 

Water also functions to support an optimal immune system. It helps transport oxygen around the body to allow for the adequate functioning of your body’s systems. Additionally, water aids in the production of lymph fluid that detoxifies the blood and circulates white blood cells and nutrients to different tissues.12 

References:

  1. Guillin, O.M., Vindry, C., Ohlmann, T., Chavatte, L. Selenium, selenoproteins and viral infection. Nutrients. 2019 [cited 2 Mar 2022]; 11(9): 2101.
  2. Molendijk, I., van der Marel, S., Maljaars, P.W. Towards a Food Pharmacy: Immunologic Modulation through Diet. Nutrients. 2019 [cited 2 Mar 2022]; 11(6): 1239.
  3. Caballero, S., Pamer, E.G. Microbiota-mediated inflammation and antimicrobial defense in the intestine. Annual review of immunology. 2015 [cited 2 Mar 2022]; 33: 227-56.
  4. Klaenhammer, T., Kleerebezem, M., Kopp, M. et al. The impact of probiotics and prebiotics on the immune system. Nat Rev Immunol. 2012 [cited 2 Mar 2022]; 12: 728–734. 
  5. Herbert, T.B. Stress and the immune system. World Health. 1994 [cited 2 Mar 2022]; 2: 4-5. 
  6. da Silveira, M. P., da Silva Fagundes, K. K., Bizuti, M. R., Starck, É., Rossi, R. C., and de Resende E Silva, D. T. Physical exercise as a tool to help the immune system against COVID-19: an integrative review of the current literature. Clinical and experimental medicine. 2021 [cited 2 Mar 2022]; 21(1): 15–28. 
  7. Nieman, D.C., Johanssen, L.M, Lee, J.W. and Arabatzis, K. Infectious episodes in runners before and after the LA marathon. The Journal of sports medicine and physical fitness. 1990 [cited 2 Mar 2022]; 30(3): 316-28. 
  8. Besedovsky, L., Lange, T. and Haack, M. The Sleep-Immune Crosstalk in Health and Disease. American Physiological Society. 2019 [cited 2 Mar 2022]; 99(3): 1325-1380. 
  9. Division of Sleep Medicine at Harvard Medical School. Sleep, Learning, and Memory [Online]. USA: Healthy Sleep. 2019 [cited 2 Mar 2022]. Available from: http://healthysleep.med.harvard.edu/healthy/matters/benefits-of-sleep/learning-memory
  10. Dimitrov, S., Lange, T., Gouttefangeas, C., et al. Gas-coupled receptor signaling, and sleep regulate integrin activation of human antigen-specific T cells. J Exp Med. 2019 [cited 2 Mar 2022]; 216 (3): 517–526.
  11. Sarkar, D., Jung, M. K., and Wang, H. J. Alcohol and the Immune System. Alcohol Research: Current Reviews. 2015 [cited 2 Mar 2022]; 37(2): 153–155.
  12. Popkin, B. M., D'Anci, K. E., and Rosenberg, I. H. Water, hydration, and health. Nutrition reviews. 2010 [cited 2 Mar 2022]; 68(8): 439–458. 

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Vicky Stogiannidou

University of Bath, BSc Biology
Vicky Stogiannidou has graduated from the University of Bath with a BSc Biology where she studied topics related to neuroscience, biochemistry and immunity. Vicky has developed a strong interest in health-related fields, one of these being nutrition. Vicky deeply believes that diet is instrumental for optimal health and is the culprit underlying many chronic diseases today. Beyond the keto diet, she has been researching heavy metals, which are found in many food sources and act as toxic catalysts for numerous diseases.

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