The Importance of Nutrition for the Immune System
Recently an international research team published a report advising how the public can support their immune system and give it the best chance of fighting the coronavirus. And guess what? They suggest nutrition is an important strategy that should be included in public health recommendations (1). If you are reading this blog you are probably aware of the importance of nutrition for all aspects of health. This is a good opportunity for this message to reach the wider public as well as governments and health officials.
Whilst the research team acknowledge that practices such as hand washing and social distancing help reduce the spread and impact of infections additional measures are necessary. The role nutrition plays in supporting the immune system is well-established. A healthy immune system is key to providing good defence against pathogenic organisms. The immune system works in a number of ways:
- by providing an exclusion barrier
- by identifying and eliminating pathogens
- by identifying and tolerating non-threatening sources of antigens
- by maintaining a memory of immunological encounters.
Nutrient deficiencies decrease immune defences, making an individual more susceptible to infection.
Evidence for Nutritional Support
Inadequate intake and status of some nutrients are widespread, leading to a decrease in resistance to infections. The research team make the following recommendations:
- Supplementation with vitamins, minerals and omega-3 fatty acids to help support optimal immune function. See blog post on Supplements for Immune Support for more information.
- Supplementation above the Recommended Dietary Allowance, but within recommended upper safety limits, for specific nutrients such as vitamins C and D.
- Public health officials are encouraged to include nutritional strategies in their recommendations to improve public health.
Foods recommended to support the immune system include:
- Fruit, vegetables, nuts and beans – contain antioxidants including polyphenols, triterpenoids and flavonoids which may reduce cell damage caused by viruses (2). Polyphenol rich foods include grapes, cherries, blackberries, blueberries, cacao, green tea and beans such as soy beans.
- Fibre – promotes the growth of good bacteria which play an important role in all aspects of health including the immune system.
- Omega 3 fatty acids – help to regulate and control the immune system. Sources of omega 3 fats include oily fish, walnuts, pumpkin seeds, chia seed, flax seeds and cold pressed oils.
- Meat – for its iron and vitamin B12 content. People who do not eat meat may need to supplement.
- Fermented foods and probiotics – support the health of the microbiome and enhance immune function (3).
- Synergy – research shows that the immune supporting properties of polyphenols can be enhanced by combining them with foods containing other antioxidants. For example combining several polyphenols with vitamins, minerals and amino acids has a greater effect than individual polyphenols (4).
- Oils – combining vegetables with oil increases the bioavailability of nutrients. For example, adding an oil based dressing to foods such as cabbage, spinach, carrots and papaya has been shown to increase the absorption of beneficial compounds (5).
- Spice it up – turmeric has become famous for it’s anti-inflammatory and immune supportive properties (6). However, curcumin from turmeric is poorly absorbed. Luckily, the bioavailability of curcumin from turmeric is increased when combined with piperine from black pepper (7,8).
- Garlic – contains allicin which is a potent, broad spectrum antimicrobial with antiviral, antifungal, antibacerial and anti-parasitic activity (9)
- Ginger – has anti-inflammatory properties and blocks the attachment of viruses to cells in the airways where they often first enter the body (10).
Professor Calder from the research team adds, “The present situation with COVID-19 shows that we cannot rely on vaccinations to limit the impact of respiratory infections. Improving our nutrition is a step we can all take to help our bodies deal with infections and limit the emergence of new, more virulent strains of viruses. We strongly encourage public health officials to make sure nutritional strategies are included in all their messaging about coping with viral infections.”
For more information about who may be particularly at risk of COVID-19 see blog post Why COVID-19 Affects Different People in Different Ways.
1. 2020 Apr 23;12(4). pii: E1181. Optimal Nutritional Status for a Well-Functioning Immune System Is an Important Factor to Protect against Viral Infections. Calder PC et al.
2. Niedzwiecki A, Roomi MW, Kalinovsky T, Rath M. Anticancer Efficacy of Polyphenols and Their Combinations. Nutrients. 2016 Sep 9;8(9). pii: E552.
3. Proc Nutr Soc. 2013 Aug;72(3):299-309. Feeding the immune system. Calder PC.
4. Urikura M, Morishige J, Tanaka T, Satouchi K. Phosphatidic Acid production in the processing of cabbage leaves. J Agric Food Chem. 2012 Nov 14;60(45)
5. Mashurabad PC, Palika R, Jyrwa YW et al. Dietary fat composition, food matrix and relative polarity modulate the micellarization and intestinal uptake of carotenoids from vegetables and fruits. J Food Sci Technol. 2017 Feb;54(2):333-341.
6. Biomed Res Int. 2014;2014:186864.A review on antibacterial, antiviral, and antifungal activity of curcumin. Moghadamtousi SZ et al.
7. Indian J Pharmacol. 2017 Jan-Feb;49(1):65-70.Cardioprotective effect of curcumin and piperine combination against cyclophosphamide-induced cardiotoxicity. Chakraborty M, Bhattacharjee A, Kamath JV.
8. Integr Med. 2016 Sep 1;13(3):247-255. Influence of piperine and quercetin on antidiabetic potential of curcumin. J Complement. Kaur G, Invally M, Chintameaneni M.
9. Microbes Infect. 1999 Feb;1(2):125-9. Antimicrobial properties of allicin from garlic. Ankri S, Mirelman D.
10. J Ethnopharmacol. 2013 Jan 9;145(1):146-51. Fresh ginger (Zingiber officinale) has anti-viral activity against human respiratory syncytial virus in human respiratory tract cell lines. Chang JS et al.