Build Your Armour Against Viruses Such as the Coronavirus

The coronavirus seems to have blindsided us all. Most of us have never been faced with a brand-new virus such as this that has spread over so much of the developed world and impacted so many people. Its onset has engendered fear, anxiety and even panic in some as we listen to the incessant news about the disease and the death that it is causing. The interconnectedness of our modern world has perhaps done us an injustice in this situation. We are alerted constantly about the numbers of people suffering and dying from Covid-19 and, because this virus is affecting much of the planet, those numbers are huge. This in-your-face wave of information magnifies the impact of this disease and only increases our alarm.

This novel (newly emerged and unknown) coronavirus has been named SARS-CoV-2 and it causes the disease known as Covid-19. It has been studied ferociously since its first appearance in the late fall of 2019 in China. Scientists in many different countries are furiously working to understand what is going on and disseminating their discoveries to all of us, keeping us in continual awareness of what is known and what is not known. Unfortunately, the corollary information that would help us to put this disease into context is not so available. How does this virus compare to the “normal” flu viruses that we deal with every winter/spring season? We don’t really know that yet and what we are being told is in a constant state of flux. Testing for presence of Covid-19 has been sporadic and, with the majority of people not being tested, we have no idea about the true incidence of the disease. Additionally, a significant percentage of people infected with this coronavirus show no symptoms at all. Japan reported that 31% of their citizens evacuated from Wuhan at the beginning of the outbreak in China and returning to Japan were found to be carrying the virus but had no symptoms, even thirty days after their return (1). Many people who are infected have only a very mild case of the disease. It is difficult to put this all into context and it is likely that only through hindsight will we be able to file this virus into its place on the hierarchy of infectious diseases.

Fortunately, we need not feel helpless in the face of this onslaught. There are quite a few steps that we can take to protect ourselves, not only from this present virus, but also from the ones that we will no doubt meet in the future. A virus such as this coronavirus was not unexpected and there will be others. Periodically over the timeline of our existence as humans we have encountered new viruses that have caused disease and death among the earth’s population. This one seems to be different, though perhaps mostly because of our contemporary state of inter-connectedness. Yes, it has spread quickly and touched many different countries but we have never had the capacity before to be kept in such a relentless state of awareness of its effects. By the time we see the end of SARS-Cov-2, the vast majority of people in affected countries will have been infected by it, usually in a mild to moderate way, and will develop immunity to it. This is likely the same outcome as has occurred for every novel virus that has challenged us over the millennia of our existence.

So what is the DIY manual for arming your body against threats from novel viruses? And if you adapt some new habits now, is there any hope that you can change your susceptibility to this disease right away. The experts say, yes! There is no better time to act than now and you will indeed be able to strengthen your body to be better prepared to fight off this bug as well as any new one that threatens your health. The intense research on the present virus along with previous lessons learned from other viruses, have identified some factors that can reduce our vulnerability to such dangers.



Nitric oxide is a signalling molecule that participates in virtually every cellular and organ function in the body. It also dilates blood vessels promoting better blood flow. Nitric oxide is produced in various locations throughout the body (2). Studies have found that nitric oxide is associated with inhibiting viral infections both in the laboratory and in live subjects. This inhibition has been observed in infections caused by both RNA- and DNA-type viruses. Coronaviruses are RNA-type viruses (3). Nitric oxide has shown an ability to inhibit early stages of viral replication, preventing viral spread and promoting viral clearance and recovery of the host (4). After the SARS outbreak in 2002/2003, which was caused by a related coronavirus called SARS-CoV or SARS-CoV-1, physicians used inhaled nitric oxide gas to treat a number of people with SARS and noticed immediate improvement in breathing and reduced need for ventilator support (5,6). In March, 2020, during the present outbreak of Covid-19, the FDA in the US began allowing “emergency expanded access” of inhaled nitric oxide delivery for treatment of this virus, noting that nitric oxide acts as a vasodilator, relaxing the lungs’ muscles and blood vessels. “Emergency expanded access” is used when the benefits of a product appear to outweigh the risks, clinical trials are not feasible and there are no available alternatives (7).

Fortunately, the human body can produce its own nitric oxide and the type of food eaten greatly influences that production. Nuts and seeds supply nitric oxide through an essential amino acid that they possess which is involved directly in the production of nitric acid in the human body (8). Also, nitrates found in plants can be converted into nitrites by bacteria present in the saliva of the mouth and a portion of these nitrites will then be transformed into health-giving nitric oxide (9). (Regrettably, nitrates from processed meat follow a different metabolic path that results in the production of harmful nitrosamines (10)) For instance, beets contain high levels of nitrates. Studies show that drinking beetroot juice can significantly raise nitric oxide levels in subjects, with one investigation measuring a 21% increase in nitric oxide levels within 45 minutes of drinking the juice (12,13). Leafy greens are also nitrate-rich and promote high blood levels of nitric oxide that are associated with many health benefits (14). In fact, all whole plant foods contain nitrates with vegetables contributing around 85% of our daily nitrate intake from food. Levels in vegetables vary with the type of the plant, however the highest nitrate levels are found in beetroot and green leafy vegetables such as chard, arugula and cabbage (15).



We have learned from the present assault of Covid-19 that the immune system status and overall health of each person determines their susceptibility to this infection and the severity of their disease. A recent report from Italy’s national health authority concerning the present coronavirus pandemic stated that 99% of the deaths from Covid-19 in Italy happened in people already struggling with chronic diseases (11).

A review from China also alerts us that patients with underlying cardiovascular diseases have increased risk of death from Covid-19 (16). The virus actually enters the body through angiotensin-converting enzyme 2 (ACE2) receptors, proteins located in the arteries, lungs and the digestive system that are involved in heart function and the development of high blood pressure and diabetes. The SARS-CoV-2 virus can bind to this enzyme and then replicate itself in the heart and lungs. People with cardiovascular disease have more ACE2 receptors compared to healthy individuals. It appears also that ACE2 receptors are increased by some of the drugs used to lower blood pressure such as angiotensin-converting enzyme inhibitors (ACE inhibitors) and angiotensin-receptor blockers (ARBs) (16).

Cardiovascular disease is not the only pre-existing condition to increase the severity of Covid-19. The CDC (Center for Disease Control) recently reported the increased rates of death from Covid-19 in people with a chronic disease (17);

CHRONIC DISEASE                             DEATH RATE
Cardiovascular disease                                 10.5%
Diabetes                                                             7.3%
Chronic respiratory disease                           6.3%
High blood pressure                                         6%
Cancer of any type                                           5.6%

Compare these high death rates to those of patients in good health before being infected who have a fatality rate of 0.9% (17).

We have abundant research that tells us that diet choices have a huge affect on the risk of chronic diseases such as obesity, cardiovascular disease, diabetes, various types of cancer and osteroporosis, specifically that eating more plant-based foods and fewer animal-based foods reduces the risks of such diseases (43).



It is clear that the more nutritious foods you consume, the more potential you will have to build up your immune system. Increasing the amount of plant-sourced foods in your diet will address your nitric oxide level, your risk for developing a chronic disease and the strength of your immune system.

Plants contain a plethora of essential nutrients. Vitamins, minerals, phytochemicals and many other compounds are critical for optimal functioning of the body including that of the immune system. Antioxidants fight against inflammation by quelling reactive oxygen species. Plants are the best source of all of these nutrients; in fact, some of them cannot be obtained anywhere other than plants (18,19,20,21). One randomized controlled trial of elderly people found that increasing consumption of fruits and vegetables to five portions a day resulted in a significant increase in nutrients crucial to efficient operation of the immune system as well as enhanced antibody response after vaccination (22). Another study found that reduced-fat diets (containing 20% of calories from fat) increase the activity of natural killer cells which are essential players in the immune system (23). Excess body fat causes a state of low-grade, chronic inflammation along with disturbed levels of metabolic hormones. This results in suppression of immunity in overweight people. Studies reported increased morbidity and mortality in obese people compared to people of normal BMI following infection with the 2009 pandemic influenza A (24). Research on high-carbohydrate, low-fat diets illustrates that these diets can help in maintaining a healthy BMI and a highly functioning immune system (25).

So, how do you embrace this information and incorporate it into your own life to fortify your immune system? The following is a suggested plan that ensures you eat all the key foods needed to achieve this objective. It is based on Dr. Michael Greger’s Daily Dozen (26) with some extra additions focusing on the immune system.

Make it your goal to include all of these listed foods in their suggested amounts in the meals you eat each day. This will provide you with about 1,400 to 1,500 calories. Once you have these listed foods covered, you can add in anything else that you choose to obtain the total number of daily calories that you need. Although be forewarned. Whole plant foods are very filling and satisfying. You may not have room left in your stomach for much extra! Choosing even more of the healthy foods on this list would be the optimum choice for your extra foods. Ideally, you’d also back off on processed foods and animal-sourced foods. They do not contain the beneficial, immune-boosting nutrients you are looking for and, whatever amount of these less nutritious foods you consume means less room in your stomach for the foods that will make you healthier. As an added bonus, the foods on this list will not only bolster your immune system but will also have other benefits. Consuming these suggested foods will promote a healthy microbiome. The human microbiome and the immune system are constantly shaping each other in a mutual aim to thrive and whole plant foods beneficially affect both the microbiome and immune response (27). In addition, you can reduce your risk of developing many chronic diseases and may even reverse diseases such as cardiovascular diseases, diabetes, cancers and autoimmune diseases.

It is important to remember that whole foods are what you are looking for, not isolated parts of whole foods. Their advantage comes from the inter-relationships between all the nutritious components making up each food. Their high fiber content slows the release of their natural sugars. Their complex mixture of nutritious ingredients can never be matched by supplements. Indeed, studies show that supplements do not provide the same benefits as the whole food and may even produce negative effects (42). Adopting a diverse diet of whole plant foods will provide your body with the raw materials it needs for peak operation of every system in your body, including your vast and complicated immune system.



Legumes – 3 servings
The legume family encompasses many different plant foods – all kinds of beans, split peas, fresh peas, chickpeas and lentils. A serving is ½ cup cooked legumes; 1 cup of fresh peas or sprouted lentils; or ¼ cup of hummus or bean dip.

Berries – 2 servings
Berries are very high in antioxidants as well as vitamins. Any kind of berries are included here – strawberries, raspberries, blackberries, blueberries and even cherries and grapes. A serving is ½ cup fresh or frozen berries; or ¼ cup dried berries.

Other fruits – 3 servings
There is a delicious variety of fruits to choose from. Be sure to eat citrus fruits regularly for immune system health. One serving is 1 medium-sized fruit; 1 cup of cut-up fruit; or ¼ cup of dried fruit.

Cruciferous vegetables – 1 serving
This remarkable family of vegetables includes broccoli, cauliflower, Brussels sprouts, kale, collard greens, arugula, cabbage, Chinese cabbage, mustard greens, radishes, broccolini and broccoli rabe. Their defining ingredient is sulforaphane which can significantly strengthen the immune system and also has remarkable benefits against various types of cancer, may decrease the risk of cardiovascular disease and help in autism and osteoporosis (28,29). One serving is ½ cup chopped; or ¼ cup Broccoli sprouts or Brussels sprouts.

Greens – 2 servings
Examples of greens are spinach, arugula, beet greens, kale, Swiss chard, watercress, dandelion greens and any young salad greens. One serving is 1 cup of raw greens; or ½ cup cooked greens.

Allium Vegetables – 1 serving
Alliums include onions, garlic, leeks, scallions, chives and shallots. They contain sulfur in the form of an organosulfur compound which has well-known health benefits. They are antioxidant, antiviral, antibacterial, anti-cancer, immune-boosting, anti-inflammatory and help prevent blood clots (30,31,32). A study on garlic found that a single meal containing garlic turned on genes related to improved immunity (33). One serving of an allium vegetable is ½ cup cooked vegetable.

Other vegetables – 2 servings
All the vegetables that haven’t been mentioned already are included here. Some examples are carrots, corn, bell peppers, green beans, tomatoes (technically a fruit but used like vegetables), sweet potatoes, squash and mushrooms. Studies on mushrooms showed increased secretion of IgA antibodies along with anti-inflammatory effects, both of which are signs of healthy immune function (34). One serving is ½ cup raw or cooked non-leafy vegetables; or ½ cup vegetable juice.

Flaxseeds or chia seeds – 1 serving
These tiny seeds contain cancer-fighting lignans as well as omega-3 fatty acids, both of which are difficult to find in other foods. Chia is lower in lignans than flaxseeds. One serving is 1 tablespoon of ground flaxseed; or 2 tablespoons of chia seeds.

Nuts and Seeds – 1 serving
All nuts are found in this section – almonds, cashews, pistachios, walnuts, peanuts, pumpkin seeds sunflower seeds among others. One serving is ¼ cup of nuts or seeds; or 2 tablespoons of nut or seed butter.

Turmeric – 1 serving
Turmeric is so healthful that it is recommended that you eat a serving of it every day. One serving is ½ teaspoonful.

Other Herbs and spices – 3 or more servings
This group is a powerful source of antioxidants which fight inflammation. Examples are cinnamon, chili powder, nutmeg, basil and oregano but of course there are many more. One serving is ¼ teaspoon.

Whole Grains – 3 servings
This category includes all whole grains such as brown rice, oats, quinoa, barley, buckwheat, amaranth, popcorn and whole-wheat pasta. One serving is ½ cup hot cereal or cooked grains; 1 slice of bread; or 3 cups popped popcorn.

11 Beverages – 5 servings
The most important beverage is of course water but tea and coffee are good too. This is in addition to the water that you obtain from all the plants you eat. Studies on green tea have found that it can prevent infection from the influenza virus (35,36). One serving is a 12-ounce glassful.



Exeercise Daily 
Studies show that moderate exercise enhances immune function and lowers the risk of a wide variety of illnesses, including infectious diseases. Even just a short brisk walk for 15 to 30 minutes can make a big difference (37). Exercise can be split up over the day. Indulging in ninety minutes of moderate-intensity activity such as brisk walking, cycling, yard work or yoga or forty minutes of vigorous activity such as jogging, weight training, cycling hills or swimming laps will go a long way to optimizing the operation of your immune system. Note: Don’t over-exercise. Prolonged strenuous exercise depresses white blood cell function and can allow viruses and bacteria to gain a foothold, allowing an infection to develop (38).

Sleep Nightly
Sleep is essential to your immunity. The amount of nightly sleep needed varies between different people, however, a good 6 to 8 hours of sleep per night is a good goal to aim for. Research has shown that lack of sleep depresses immunity (39).

Avoid Stress
Acute, short-lived stress can prepare the immune system for “fight or flight” dangers such as imminent injury. However, chronic stress is associated with decreases in almost all measures of immunity (40). One study showed that rates of catching a respiratory infection such as a cold increased along with the degree of psychological stress in the participants (41).

Try as much as you can to avoid stress. Avoid following the news too closely and shut it off when you realize it is starting to drag you down. Exercise each day. Take the time to indulge in activities that bring you relaxation – read a book; play or listen to music; watch a comedy movie or TV show; practice stretching, meditation or yoga.



It may take you awhile to integrate these changes into your daily life. You can decide to take it slowly or go all in if that is better for you. Remember that you have a very good reason to do this. Changing your lifestyle to promote better health is an empowering thing to do. When the next threat to your wellbeing approaches, you can be confident that you have done everything that you can to arm yourself against it. This alone will help you relax and get on with life in spite of possible risks. In addition, all the changes that you make will have you feeling healthier, stronger and more energetic and, inevitably, happier as well.




2 Luiking, Y.C., Engelen, M.P., Deutz, N.E. Regulation of nitric oxide production in health and disease. Curr Opin Clin Nutr Metab Care. 2010; 13(1): 97–104. doi:10.1097/MCO.0b013e328332f99d


4 Reiss, C.S., Komatsu, T. Does nitric oxide play a critical role in viral infections?. J Virol. 1998;72(6):4547–4551.

5 Groneberg, D.A., Poutanen, S.M., Low, D.E., Lode, H., Welte, T., Zabel, P. Treatment and vaccines for severe acute respiratory syndrome. The Lancet. March 1, 2005; 5(3): 147-155.

6 Akerström, S., Mousavi-Jazi, M., Klingström, J., Leijon, M., Lundkvist, A., Mirazimi, A. Nitric Oxide Inhibits the Replication Cycle of Severe Acute Respiratory Syndrome Coronavirus. J Virol. Feb 2005; 79(3).


8 Mirmiran, P., Bahadoran, Z., Ghasemi, A., Azizi, F. The Association of Dietary l-Arginine Intake and Serum Nitric Oxide Metabolites in Adults: A Population-Based Study. Nutrients. 2016;8(5):311.

9 Bondonno, C.P., Croft, K.D., Puddey, I.B., Considine, M.J., Yang, X., Ward, N.C., Hodgson, J.M. Nitrate causes a dose-dependent augmentation of nitric oxide status in healthy women. Food Funct. 2012 May;3(5):522-527.

10 Scanlan, R.A. Encyclopedia of Food Sciences and Nutrition (Second Edition): Nitrosamines. 2003; Pages 4142-4147


12 Kroll, J.L., Werchan, C.a., Rosenfield, D., Ritz, T. Acute ingestion of beetroot juice increases exhaled nitric oxide in healthy individuals. PLoS One. 2018 Jan 25;13(1):e0191030.

13 Baião Ddos, S., Conte-Junior, C.A., Paschoalin, V.M., Alvares, T.S. Beetroot juice increase nitric oxide metabolites in both men and women regardless of body mass. Int J Food Sci Nutr. 2016;67(1):40-46.

14 Milkowski, A., Garg, H.K., Coughlin, J.R., Bryan, N.S. Nitric Oxide – Nutritional epidemiology in the context of nitric oxide biology: A risk–benefit evaluation for dietary nitrite and nitrate . 2010 Feb 15; 22(2):110-119.

15 Lundberg, J.O., Weitzberg, E., Gladwin, M.T. The nitrate-nitrite-nitric oxide pathway in physiology and therapeutics. Nat Rev Drug Discov. 2008 Feb;7(2): 156-617.

16 Zheng, Y.-Y., Ma, Y.-T., Zhang, J.-Y. COVID-19 and the cardiovascular system. Nature Reviews Cardiology. March 5, 2020.



19 Rodriguez-Casado, A. The Health Potential of Fruits and Vegetables Phytochemicals: Notable Examples. Crit Rev Food Sci Nutr. 2016 May 18; 56(7):1097-1107. doi: 10.1080/10408398.2012.755149.

20 Leitzmann, C. Characteristics and Health Benefits of Phytochemicals. Forsch Komplementmed. 2016;23(2): 69-74. doi: 10.1159/000444063.

21 Liu, R.H. Health-promoting components of fruits and vegetables in the diet. Adv Nutr. 2013 May 1;4(3):384S-392S. doi: 10.3945/an.112.003517.

22 Gibson, A., Edgar, J.D., Neville, C.E., Gilchrist, S.E., McKinley, M.C., Patterson, C.C., Young, I.S., Woodside, J.V. Effect of fruit and vegetable consumption on immune function in older people: a randomized controlled trial. Am J Clin Nutr. 2012 Dec; 96(6):1429-1436. doi: 10.3945/ajcn.112.039057.

23 Hebert, J.R., Barone, J., Reddy, M.M., Backlund, J.-Y. C. Natural killer cell activity in a longitudinal dietary fat intervention trial. Clinical Immunology and Immunopathology. 1991; 54(1), 103–116. doi:10.1016/0090-1229(90)90010-n

24 Milner, J.J., Beck, M.A. The impact of obesity on the immune response to infection. Proc Nutr Soc. 2012 May; 71(2): 298-306. doi: 10.1017/S0029665112000158.

25 Santos, M. Immunological effects of low-fat diets with and without weight loss. J Am Coll Nutr. 2003 Apr; 22(2): 174-182.


27 Mezouar, S., Chantran, Y., Michel, J., Fabre, A., et al. Microbiome and the immune system: From a healthy steady-state to allergy associated disruption. Human Microbiome Journal. December, 2018; 10: 11-20.

28 Vanduchova, A., Anzenbacher, P., Anzenbacherova, E.. Isothiocyanate from Broccoli, Sulforaphane, and Its Properties. J Med Food. 2019 Feb;22(2): 121-126.

29 Houghton, C.A. Sulforaphane: Its “Coming of Age” as a Clinically Relevant Nutraceutical in the Prevention and Treatment of Chronic Disease. Oxid Med Cell Longev. 2019; 2019:2716870.

30 Arreola, R., Quintero-Fabián, S., López-Roa, R.I., et al. Immunomodulation and anti-inflammatory effects of garlic compounds. J Immunol Res. 2015; 2015:401630. doi:10.1155/2015/401630

31 Zhou, Y., Zhuang, W., Hu, W., Liu, G.J., Wu, T.X., Wu, X.T. Consumption of large amounts of Allium vegetables reduces risk for gastric cancer in a meta-analysis. Gastroenterology. 2011 Jul;141(1):80-89.

32 Majewski, M. Allium sativum: facts and myths regarding human health. Rocz Panstw Zakl Hig. 2014;65(1):1-8.

33 Charron, C.S., Dawson, H.D., Albaugh, G P., Solverson, P.M., Vinyard, B.T., Solano-Aguilar, G I., et al. A Single Meal Containing Raw, Crushed Garlic Influences Expression of Immunity- and Cancer-Related Genes in Whole Blood of Humans. The Journal of Nutrition. 2015;145(11), 2448–2455.

34 Jeong, S.C., Koyyalamudi, S.R., Pang, G. Dietary intake of Agaricus bisporus white button mushroom accelerates salivary immunoglobulin A secretion in healthy volunteers. Nutrition. 2012 May; 28(5):527-531. doi: 10.1016/j.nut.2011.08.005.

35 Matsumoto, K., Yamada, H., Takuma, N., Niino, H., Sagesaka, Y. M. Effects of Green Tea Catechins and Theanine on Preventing Influenza Infection among Healthcare Workers: A Randomized Controlled Trial. BMC Complementary and Alternative Medicine 2011; 11(1). doi:10.1186/1472-6882-11-15

36 Song, J.-M., Lee, K.-H.,Seong, B.-L. Antiviral effect of catechins in green tea on influenza virus. Antiviral Research 2005; 68(2): 66–74. doi:10.1016/j.antiviral.2005.06.010

37 Nieman, D.C., Wentz, L.M. The compelling link between physical activity and the body’s defense system . Journal of Sport and Health Science. May 2019; 8(3): 201-217.

38 Walsh, N.P., Gleeson, M., Shephard, R.J., Gleeson, M., Woods, J.A. et al. Position Statement Part One: Immune function and exercise. Exerc. Immunol. Rev. 201l; 17:6-63.

39 Walsh, N.P., Gleeson, M., Pyne, D.B., Nieman, D.C., Dhabhar, F.S. et al. Position Statement Part Two:Maintaining Immune Health. Exerc. Immunol. Rev. 2011; 17:64-103.

40 Segerstrom, S.C., Miller, G.E. Psychological stress and the human immune system: a meta-analytic study of 30 years of inquiry. Psychol Bull. 2004 Jul;130(4):601-30.

41 Cohen, S., Tyrrell, D.A.J., Smith, A.P. Psychological Stress and Susceptibility to the Common Cold. N Engl J Med. 1991; 325: 606-612.



Promoting a healthy adventurous lifestyle powered by plants and the strength of scientific evidence.

My name is Debra Harley (BScPhm) and I welcome you to my retirement project, this website. Over the course of a life many lessons are learned, altering deeply-rooted ideas and creating new passions.


  1. Ruth Russell on April 24, 2020 at 1:48 pm

    Thanks Deb. Reading this article was a good reminder of the best foods to be consuming during this pandemic and going forward.

    • Deb on April 26, 2020 at 9:48 pm

      Thanks Ruth. I’m glad you found this article useful.

Leave a Comment