It is not possible for specific foods, nutritional supplements, and dietary interventions to cure or even control inflammation for everyone and individual food groups alone cannot contribute to better immune system functioning; however, there are food groups which research has associated with being supportive for aiding in a healthy balanced lifestyle to collectively boost immune system function and minimise long term inflammation.
Remember, nutrition is a conflicting field and whilst research does support the content we discuss, it’s still a field of ongoing change.
What Does the Immune System Do?
Be honest? How many times did you hear or read the words ‘immune system’ since the start of the 2020 pandemic? Almost every day for a year in my experience.
So, you might be asking, what is the immune system and what does it do? The immune system is a complex innate system, that protects us from becoming seriously sick when exposed to viruses, bacteria, fungi and toxins (Muscogiuri et al.,2021).
When these foreign substances are detected by the body, the immune cells (phagocytes/lymphocytes) respond by releasing antibodies (cytokines) to bind and terminate any further spread of foreign proteins. This in turn prevents a more severe illness in healthy people (Muscogiuri et al.,2021). When the immune system is actively fighting off foreign substances it initiates inflammation which is a natural reaction. Once the infection has been controlled, inflammation is reduced. However, ongoing inflammation becomes detrimental to health and has been associated with a range of chronic health conditions including obesity, heart disease and diabetes.
Nutritional Considerations to Boost the Immune System Function and Reduce Inflammation.
Since the body reacts in different ways for every client, particularly when chronic health conditions exist too, it is extremely challenging to state that specific foods should be consumed or avoided. However, the goal is to consume a balanced diet which works to minimise the activation of the innate immune system. The diet consumed should minimise excessive production of proinflammatory cytokines by promoting anti-inflammatory cytokines instead. The main strategies achieved through balanced nutrition include:
1) Maintain a healthy weight
Research suggests that obese individuals are more susceptible to infectious disease as a result of a reduced inflammatory response, hyperinsulinemia, hyperglycaemia and hyperleptinemia (Muscogiuru et al., 2021).
2) Consume Antioxidant Promoting Foods – to control inflammatory responses
3) Minimise Hyperinsulinemia – to control inflammatory responses
Let’s briefly explore some nutritional components which are suggested to potentially control inflammation and boost the immune system’s function.
Fruit and Vegetables
Fruit and vegetables are high in antioxidants, micronutrients and photochemical. These nutrients break down free radicals and reduce inflammation. The recommended daily intake of fruit and vegetables is 5+ per day. (Zhu et al., 2018).
Fibre is one of the most important nutrients for health as it binds to cholesterol and blunts the response of insulin after a meal.
This may promote better heart health and lower the risk of type 2 diabetes.
Fibre also acts as a prebiotic for the gut microbiota. Gut microbiota plays a vital role in regulating the functions of the immune system; therefore, we must not neglect dietary fibre.
Coaches and trainers can recommend at least 18-22g of fibre per day (Rijnaarts et al.,2021).
Fish Oils and Omega 3 Supplementation
Fish oils are suggested to inhibit the catalyst enzyme cyclooxygenase that triggers inflammation. Omega 3 can also be taken up through supplementation.
(Chen et al.,2022)
Protein and Dairy Intake
Dietary protein intake is crucial to promoting a healthy immune system.
Being deficient in dietary protein can impair the body’s ability to produce immune cells. Amino acids prevent the spread of infections and eliminate bacteria by activating natural killer cells and they also help to regulate the body’s response to oxidative stress which in turn reduces inflammation. The impact amino acids have on the immune system, cytokine release and prevention of inflammation is very significant (and complex) and warrants further reading and investigation.
Dairy is also suggested to help control inflammation but the mechanisms through which this is achieved are still not fully understood.
Vitamins and minerals are essential elements of nutrition which contribute to a healthier immune system overall (Gorji and Ghadri 2021). This does not mean that everyone needs to supplement their micronutrients but instead look at their existing diet to evaluate what they receive sufficient levels of and what areas may be lacking.
Of course, it is important to recommend clients consume 5 or more different fruits and vegetables per day to help achieve this balance.
If a client finds it difficult to get micronutrients from the diet, then it may be appropriate for them to supplement them, but this is a conversation they can have with a dietician or qualified professional.
Vitamin D intake
Deficiency in vitamin D may reduce the body’s ability to produce the molecules that fight off an infectious disease (Bui et al., 2021). Vitamin D can be attained through diet or sunlight exposure.
The recommended vitamin D intake is at least 800IU (Cosman et al., 2014).
Minimise Intake of the Following
Foods which have very low anti-inflammatory properties or contribute to the elevation of insulin should be minimised in an effort to balance out the markers in the body to control inflammation and boost immune function. These include refined carbohydrates and fried and processed foods. Also, consideration should be taken in relation to the balance between Omega 6 and Omega 3. Omega 6 can potentially produce pro-inflammatory reactions in the body but can be safely offset with the balance of Omega 3.
In summary, a balanced diet will continue to be recommended. Often a Mediterranean style diet is recommended by many organisations supporting people with chronic health conditions due to the balance of fruits and vegetables and limitations of processed foods. Keeping it simple is key. In addition to nutrition, there are many factors which can contribute to a healthy immune system and reduced potential for inflammation such as stress management, sleeping and activity.
Bui, L., Zhu, Z., Hawkins, S., et al. ‘Vitamin D regulation of the immune system and its implications for COVID-19: A mini review’ SAGE Open Medicine 9 (1): 20503121211014073
Chen, J., Jayachandran, M., Bai, W., et al. (2022). ‘A critical review on the health benefits of fish consumption and its bioactive constituents’ Food Chemistry 369 (1):130874
Cosman, F., LeBoff, M.S., Lewiecki, E.M., et al. (2014). ‘Clinician’s Guide to Prevention and Treatment of Osteoporosis’ Osteoporosis International 26 (7): 2045
Gorji, A., &., Ghadri, M.K. (2021). Potential roles of micronutrient deficiency and immune system dysfunction in the coronavirus disease 2019 (COVID-19) pandemic. Nutrition 82:111047
Gwin, J.A., Church, D.D., Hatch-McChesnev, A., et al. (2021). ‘Effects of high versus standard essential amino acid intakes on whole-body protein turnover and mixed muscle protein synthesis during energy deficit: A randomized, crossover study’ Clinical Nutrition 40 (3): 767-777
Muscogiuri, G., Pugliese, G., Laudisio, D., et al. (2021). ‘The impact of obesity on immune response to infection: plausible mechanisms and outcomes’ Obesity Reviews 22 (6):e13216
Rajput, S., Paliwal, D., Nathanie., et al. (2021). ‘COVID-19 and gut microbiota: a potential connection’ Indian Journal of Clinical Biochemistry 36 (3): 266-277
Rignaarts, I., De Roos, N.M., Wang, T., et al. (2021). Increasing dietary fibre intake in healthy adults using personalised dietary advice compared with general advice: a single-blind randomised controlled trial. Public Health Nutrition 24 (5): 1117-1128
Rogeri, P.S., Zanella, R., Martins, G.L., et al. (2022). ‘Strategies to Prevent sarcopenia in the aging process: Role of Protein Intake and Exercise’ Nutrients 14(52): 1-33
Hess, J. M., Stephensen, C. B., Kratz, M., & Bolling, B. W. (2021). Exploring the Links between Diet and Inflammation: Dairy Foods as Case Studies. Advances in nutrition (Bethesda, Md.), 12(Suppl 1), 1S–13S. https://doi.org/10.1093/advances/nmab108
Lee, Y., Bae, S., Song, G. (2012). ‘Omega-3 Polyunsaturated Fatty Acids and the Treatment of Rheumatoid Arthritis: A Meta-analysis’ Archives of Medical Research. 45(3): 356-362
Zhu, F., Du, B., Xu, B. (2018). ‘Anti-inflammatory effects of phytochemicals from fruits, vegetables, and food legumes: A review’ Critical Review in Food Science and Nutrition 58(8):1260-1270