Share on facebook
Share on twitter
Share on linkedin

Nutrition, Lifestyle, Immunity and the Novel Coronavirus (COVID-19)

The novel coronavirus (COVID-19) poses a significant threat to public health and the global economy. In this article, Cliff looks into how we can best reduce our risks of transmission while also staying healthy.
Infographic: Patients with COVID-19 have reportedly had mild to severe respiratory illness. Symptoms include: fever, cough, and shortness of breath.

Immunity is a BIG topic right now due to the emergence of COVID-19 (the novel coronavirus). The emergence of this new form of coronavirus also resulted in greater awareness of the public health implications of other seasonal illnesses like influenza, flu-like viruses, and the common cold (itself often caused by a form of coronavirus or rhinovirus) which result in significant numbers of hospitalisations and deaths every year.

COVID-19 has recently been upgraded to a pandemic.

Total number of COVID cases over time

Because there is a lot of concern (and quite rightly so) about the potential implications of COVID for public health, society, and the economy, there has been a lot of discussion online about how we might avoid the virus. This advice runs the gamut from sensible, through to ridiculous (ummm 5G causes COVID… yeah… OK…)

advice runs the gamut from sensible, through to ridiculous (ummm 5G causes COVID… yeah… OK…)

In a nutshell, when we’re talking about immunity, we’re referring to the actions of the immune system. This system is the body’s defence system (along with physical barriers like skin) and it protects us against pathogens (viruses, bacteria, protozoa, and fungi) that can cause disease.

Note: If you’re currently feeling unwell or have any unexplained symptoms, please contact your medical doctor!

Symptoms of COVID-19 include:

  • a cough
  • a high temperature (at least 38°C)
  • shortness of breath
  • Less commonly: muscle pain, sputum production, sore throat


What is COVID?

Coronavirus disease 2019 (COVID-19) is disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

While the majority of cases result in mild symptoms, the disease can result in pneumonia and multi-organ failure. The case fatality rate is estimated to be between 1% and 5% with the greatest impact in those older or immune-compromised. The infection is spread from one person to others via respiratory droplets, often produced during coughing or sneezing.


Reducing the spread of COVID-19

Despite what many alt-health gurus are claiming, there are NO supplements, diet interventions, or lifestyle interventions that can cure COVID-19 or prevent someone being infected and claims of such are unwarranted at best and dangerous at worst.

Despite what many alt-health gurus are claiming, there are NO supplements, diet interventions, or lifestyle interventions that can cure COVID-19

The best ways to reduce the spread of COVID and your likelihood of catching it are also the best practices for avoiding other cold- and flu-like viruses, namely (from the New Zealand Ministry of Health):

  • Cough or sneeze into your elbow or by covering your mouth and nose with tissues.
  • Put used tissues in the bin or a bag immediately.
  • Wash your hands with soap and water often (for at least 20 seconds).
  • Try to avoid close contact with people who are unwell.
  • Don’t touch your eyes, nose or mouth if your hands are not clean.
  • Avoid personal contact, such as kissing, sharing cups or food with sick people.
  • Clean and disinfect frequently touched surfaces and objects, such as doorknobs.
  • Stay home if you feel unwell.

[In New Zealand, call Healthline on 0800 358 5453 if you have any symptoms and have been to any countries or territories of concern or have been in close contact with someone confirmed with COVID-19]

Can nutrition support a healthy immune system?

While there is a lot of misinformation circulating about ‘natural’ or ‘alternative’ remedies for COVID-19 and other flu-like viruses which isn’t helpful, the backlash against people talking about ways they can support the immune system through sound, sensible actions like eating a healthy diet, sleeping well, and reducing lifestyle stressors is equally unwarranted…

Yes, many of the claims being made for Supplement X or Herb Y are spurious, BUT being healthy is known to be protective against the effects of many viruses, and this is likely to be the case with COVID-19 too. Please be clear, I’m not suggesting that being healthy will stop you catching it or prevent serious effects, but the healthier one is, the more likely it will be that they will have better resistance to infection and a stronger chance of recovery without serious effects.

Being healthy is known to be protective against the effects of many viruses

In other words, the healthier you are, the more likely you will be (in general) to have milder effects from colds and flu-like viruses and this may mean you are less prone to serious effects from viruses like COVID-19.

A healthy diet that that provides sufficient energy, essential fats, protein, and micronutrients will help us to be healthier and more resilient in the face of pathogens. On the other hand, diets that are high in processed and refined foods, and especially those high in trans-fats and sugar are likely to worsen responses to infections.

In addition, some nutrients (many of which are commonly lacking) have been shown to help support immunity. For example, many people in New Zealand fail to get enough vitamin A from diet alone, (1) and this vitamin is intricately involved in immunity, (2) and having sufficient Vitamin A is associated with immunity to illness and infections. (3, 4) Similarly, vitamin E also has anti-inflammatory and immunomodulatory effects, (5) and vitamin D is a key immune regulator and has also shown promise for aiding several auto-immune conditions like systemic lupus and rheumatoid arthritis. (6)

Vitamin C is getting a lot of attention in the wake of the COVID pandemic, both positive and negative. And, while contrary to popular belief, vitamin C probably won’t cure the common cold, research suggests that it might help to reduce symptoms of colds and shorten their duration, (7) and might even help to prevent the occurrence of colds in athletes and others prone to higher levels of stress (when taken regularly). (8, 9) Research also shows that bioflavonoids from plants reduce upper-respiratory-tract infections. (10) Other antioxidant-rich foods like grapeseed,  rosehips, and cacao improve antioxidant status and immunity and reduce inflammation. (11-16)

There is also the suggestion that some herbs, (17-26) spices (like turmeric), (27) and mushrooms (Lion’s Mane, Shiitake, Reishi, Chaga) may offer either anti-viral effects or provide other benefits to immune function, (28-32) and probiotic supplementation is also likely to reduce the incidence and severity of respiratory infections. (33-38)

Take home message:

None of this is to say that these foods will be effective against COVID!

But it is prudent to improve your baseline health by eating a nutrient-dense diet based on unrefined foods.

  • Eat your veggies
  • Choose unrefined foods
  • Base your meals on protein
  • But don’t think that because you eat ‘clean’ you’re immune to COVID
  • AND just because you’re young and healthy…don’t be a dick by risking being a carrier and infecting those less fortunate!

Lifestyle and immunity


Exercise is known to improve health overall, and specifically the functions of the immune system. However, excessive amounts of exercise, leading to over-stress and overtraining can result in impaired immune function and greater risk of infections, especially colds and flu-like viruses. (39)


Stress, in particular work-related stress is known to impact the immune system and reduce resistance to infections. (40) Interestingly, the effort-to-reward ratio (how much we value the benefits from our job versus the effort it requires) has a greater effect on immunity than overwork. (41)

Other factors that can negatively affect immunity:

  • Poor sleep
  • Smoking
  • Excessive alcohol use

Take home message:

Exercising, but not overtraining, getting quality sleep, and reducing undue stress (especially work-related stress) are likely to help to increase your resilience in the face or pathogens.

I do all these things…should I even be worried about COVID?

Even if you are healthy, eat well, exercise, and get enough sleep, along with minimal stress, you can still contract COVID!

While we don’t want to promote a culture of excessive fear, it is very important to do all we can to reduce the spread of this illness as we simply do not know all of the ramifications of it at this time, and by all accounts it appears to be more aggressive and with a higher mortality rate than influenza.

While we don’t want to promote a culture of excessive fear, it is very important to do all we can to reduce the spread of this illness

If you’re young and healthy, you may not experience the severest effects, which typically occur in the aged and immune-compromised, or those without access to quality public health facilities, but you can still contract the illness and you can still be a carrier.

In fact, someone who contracts the illness and has milder symptoms (i.e. those ‘healthier’) may be a greater ‘spreader’ of the illness because they will exhibit less symptoms and will be more likely to leave home, and may not be so prudent with actions like handwashing, sneezing, and avoiding close contact with others.

‘Healthier’ people risk becoming ‘spreaders’ of the illness

So, live a healthy lifestyle and do all you can to live your best life…BUT don’t be a dick and risk becoming a carrier who infects people who may have a lesser chance of fighting off the illness.

Infographic: You can help prevent the spread of respiratory illness with these actions: Avoid close contact with people who are sick. Avoid touching your eyes, nose, and mouth. Wash hands often with soap and water for at least 20 seconds.


1.         University of Otago and Ministry of Health. A Focus on Nutrition: Key findings of the 2008/09 New Zealand Adult Nutrition Survey. Wellington; 2011.

2.         Wiseman EM, Bar-El Dadon S, Reifen R. The vicious cycle of vitamin a deficiency: A review. Critical Reviews in Food Science and Nutrition. 2017;57(17):3703-14.

3.         Mayo-Wilson E, Imdad A, Herzer K, Yakoob MY, Bhutta ZA. Vitamin A supplements for preventing mortality, illness, and blindness in children aged under 5: systematic review and meta-analysis. BMJ. 2011;343:d5094.

4.         Cruz S, da Cruz SP, Ramalho A. Impact of Vitamin A Supplementation on Pregnant Women and on Women Who Have Just Given Birth: A Systematic Review. Journal of the American College of Nutrition. 2018;37(3):243-50.

5.         Nazrun Shuid A, Das S, Mohamed IN. Therapeutic effect of Vitamin E in preventing bone loss: An evidence-based review. International Journal for Vitamin and Nutrition Research. 2019:1-14.

6.         Franco AS, Freitas TQ, Bernardo WM, Pereira RMR. Vitamin D supplementation and disease activity in patients with immune-mediated rheumatic diseases: A systematic review and meta-analysis. Medicine. 2017;96(23):e7024-e.

7.         Hemila H, Chalker E. Vitamin C for preventing and treating the common cold. The Cochrane database of systematic reviews. 2013;1:CD000980.

8.         Van Straten M, Josling P. Preventing the common cold with a vitamin C supplement: a double-blind, placebo-controlled survey. Advances in therapy. 2002;19(3):151-9.

9.         Sasazuki S, Sasaki S, Tsubono Y, Okubo S, Hayashi M, Tsugane S. Effect of vitamin C on common cold: randomized controlled trial. Eur J Clin Nutr. 2006;60(1):9-17.

10.       Braakhuis AJ, Somerville VS, Hopkins WG. Effect of Flavonoids on Upper Respiratory Tract Infections and Immune Function: A Systematic Review and Meta-Analysis. Advances in Nutrition. 2016;7(3):488-97.

11.       Nuttall SL, Kendall MJ, Bombardelli E, Morazzoni P. An evaluation of the antioxidant activity of a standardized grape seed extract, Leucoselect. Journal of clinical pharmacy and therapeutics. 1998;23(5):385-9.

12.       Kar P, Laight D, Rooprai HK, Shaw KM, Cummings M. Effects of grape seed extract in Type 2 diabetic subjects at high cardiovascular risk: a double blind randomized placebo controlled trial examining metabolic markers, vascular tone, inflammation, oxidative stress and insulin sensitivity. Diabet Med. 2009;26(5):526-31.

13.       Patel S. Rose hip as an underutilized functional food: Evidence-based review. Trends in Food Science & Technology. 2017;63:29-38.

14.       Espinoza T, Valencia E, Quevedo R, Díaz O. Physical and chemical properties importance of Rose hip (R. canina, R. rubiginosa): a review. Scientia Agropecuaria. 2016;7(1):67-78.

15.       Araujo QRD, Gattward JN, Almoosawi S, Parada Costa Silva MdGC, Dantas PADS, Araujo Júnior QRD. Cocoa and Human Health: From Head to Foot—A Review. Critical Reviews in Food Science and Nutrition. 2016;56(1):1-12.

16.       Martín MÁ, Ramos S. Health beneficial effects of cocoa phenolic compounds: a mini-review. Current Opinion in Food Science. 2017;14:20-5.

17.       Almatroudi A, Alsahli MA, Alrumaihi F, Allemailem KS, Rahmani AH. Ginger: A novel strategy to battle cancer through modulating cell signalling pathways. Current pharmaceutical biotechnology. 2019.

18.       de Lima RMT, dos Reis AC, de Menezes A-APM, Santos JVdO, Filho JWGdO, Ferreira JRdO, et al. Protective and therapeutic potential of ginger (Zingiber officinale) extract and [6]-gingerol in cancer: A comprehensive review. Phytotherapy Research. 2018;32(10):1885-907.

19.       Jafarzadeh A, Nemati M. Therapeutic potentials of ginger for treatment of Multiple sclerosis: A review with emphasis on its immunomodulatory, anti-inflammatory and anti-oxidative properties. Journal of Neuroimmunology. 2018;324:54-75.

20.       Shergis JL, Zhang AL, Zhou W, Xue CC. Panax ginseng in Randomised Controlled Trials: A Systematic Review. Phytotherapy Research. 2013;27(7):949-65.

21.       Lee DC, Lau AS. Effects of Panax ginseng on tumor necrosis factor-α-mediated inflammation: a mini-review. Molecules (Basel, Switzerland). 2011;16(4):2802-16.

22.       Jamil SS, Nizami Q, Salam M. Centella asiatica (Linn.) Urban—a review. 2007.

23.       Arora D, Kumar M, Dubey S. Centella asiatica-A Review of it’s Medicinal Uses and Pharmacological Effects. Journal of Natural remedies. 2002;2(2):143-9.

24.       Tiwari R, Chakraborty S, Saminathan M, Dhama K, Singh SV. Ashwagandha (Withania somnifera): Role in safeguarding health, immunomodulatory effects, combating infections and therapeutic applications: A review. J Biol Sci. 2014;14(2):77-94.

25.       Block KI, Mead MN. Immune System Effects of Echinacea, Ginseng, and Astragalus: A Review. Integrative Cancer Therapies. 2003;2(3):247-67.

26.       Nieto G, Ros G, Castillo J. Antioxidant and Antimicrobial Properties of Rosemary (Rosmarinus officinalis, L.): A Review. Medicines. 2018;5(3):98.

27.       Fallah Huseini H, Zahmatkash M, Haghighi M. A review on pharmacological effects of Curcuma longa L.(turmeric). Journal of Medicinal Plants. 2010;1(33):1-15.

28.       Lee HH, Lee JS, Cho JY, Kim YE, Hong EK. Study on immunostimulating activity of macrophage treated with purified polysaccharides from liquid culture and fruiting body of Lentinus edodes. Journal of microbiology and biotechnology. 2009;19(6):566-72.

29.       Gaullier J-M, Sleboda J, Ofjord ES, Ulvestad E, Nurminiemi M, Moe C, et al. Supplementation with a Soluble Beta-Glucan Exported from Shiitake Medicinal Mushroom, <i>Lentinus edodes</i> (Berk.) Singer Mycelium: a Crossover, Placebo-Controlled Study in Healthy Elderly. 2011;13(4):319-26.

30.       Sheu S-C, Lyu Y, Lee M-S, Cheng J-H. Immunomodulatory effects of polysaccharides isolated from Hericium erinaceus on dendritic cells. Process Biochemistry. 2013;48(9):1402-8.

31.       Soccol CR, Bissoqui LY, Rodrigues C, Rubel R, Sella SRBR, Leifa F, et al. Pharmacological Properties of Biocompounds from Spores of the Lingzhi or Reishi Medicinal Mushroom <i>Ganoderma lucidum</i> (Agaricomycetes): A Review. 2016;18(9):757-67.

32.       Song H-S, Lee Y-J, Kim S-K, Moon K, Moon W, Kim D, et al. Downregulatory Effect of AGI-1120 (Ñß-Glucosidase Inhibitor) and Chaga Mushroom (Inonotus obliquus) on Cellular NF-kB Activation and Their Antioxidant Activity. Korean Journal of Phamacognosy. 2004.

33.       de Araujo GV, de Oliveira Junior MH, Peixoto DM, Sarinho ESC. Probiotics for the treatment of upper and lower respiratory-tract infections in children: systematic review based on randomized clinical trials. Jornal de Pediatria. 2015;91(5):413-27.

34.       Ahanchian H, Kianifar H, Ganji T, Kiani M, Khakshour A, Jafari S. Probiotics in childhood upper respiratory tract infections: a systematic review. Journal of North Khorasan University of Medical Sciences. 2015;7(2):445-52.

35.       Ozen M, Kocabas Sandal G, Dinleyici EC. Probiotics for the prevention of pediatric upper respiratory tract infections: a systematic review. Expert Opinion on Biological Therapy. 2015;15(1):9-20.

36.       Peng Y, Li A, Yu L, Qin G. The Role of Probiotics in Prevention and Treatment for Patients with Allergic Rhinitis: A Systematic Review. American Journal of Rhinology & Allergy. 2015;29(4):292-8.

37.       Güvenç IA, Muluk NB, Mutlu FŞ, Eşki E, Altıntoprak N, Oktemer T, et al. Do Probiotics have a role in the Treatment of Allergic Rhinitis? A Comprehensive Systematic Review and Metaanalysis. American Journal of Rhinology & Allergy. 2016;30(5):e157-e75.

38.       Zajac AE, Adams AS, Turner JH. A systematic review and meta-analysis of probiotics for the treatment of allergic rhinitis. International Forum of Allergy & Rhinology. 2015;5(6):524-32.

39.       Jones AW, Davison G. Chapter 15 – Exercise, Immunity, and Illness. In: Zoladz JA, editor. Muscle and Exercise Physiology: Academic Press; 2019. p. 317-44.

40.       Nakata A. Psychosocial Job Stress and Immunity: A Systematic Review. In: Yan Q, editor. Psychoneuroimmunology: Methods and Protocols. Totowa, NJ: Humana Press; 2012. p. 39-75.

41.       Eddy P, Heckenberg R, Wertheim EH, Kent S, Wright BJ. A systematic review and meta-analysis of the effort-reward imbalance model of workplace stress with indicators of immune function. Journal of Psychosomatic Research. 2016;91:1-8.

Share this post

Share on facebook
Share on twitter
Share on linkedin
Share on pinterest
Share on print
Share on email