Antiviral Foods

Mar 26, 2020 | Nutrition

Antiviral foods

COVID-19 (SARS-CoV-2) has changed our world. In these unprecedented times is hard to know what to do and how to act.  However, there is one thing that everyone agrees with, now is the time to look after our bodies.  Setting ourselves on the path to holistic health has never made more sense than now. Which is precisely the goal of the Healthy 2Day process.

Every aspect of the Healthy 2Day SENST, holistic health wheel and every tip helps to put us one step closer to holistic health. Right now, we need to look at how to boost our immune systems, specifically relating to coronavirus. Each of the SENST wheel wedges helps to strengthen your immune system. Therefore, this is the first in a five-part series. The series will cover each of the five areas of the SENST wheel outlining tips to boost your immune system in each area.

In this article, I will review nutrition and how to eat to not only boost your immune system but also, specifically protect against coronavirus with antiviral foods. Luckily, there are some studies from SARS and MERS and other coronaviruses.  There are also a few emerging studies on COVID-19 (SARS-CoV-2). Where applicable, I have included them as references throughout this article. 

Please note:

  1. these antiviral foods are not intended to treat coronavirus, I am simply conveying scientific information. Please consult medical advice before consuming the herbs, spices and foods mentioned here. Please refer to the Healthy 2Day  health disclaimer here for more information
  2. most of these studies are conducted in vitro, meaning, in a laboratory Petri dish or test tube, not on humans.  Therefore, it is unclear how the results will vary for human application.  However, most of the antiviral foods outlined in this article are healthy foods and are generally beneficial when incorporated into your normal diet, unless stated otherwise.

This is quite a long article since I cover general nutritional immune-boosting tips as well as the research for each of the antiviral foods specific to coronavirus strains or general viruses. I also suggested cooking methods to maximise the bioavailability of the antiviral compound. However, if you wish to jump to the conclusion, you can do so here: jump to the conclusion.


According to the American National Institute of Allergies and Infectious Diseases, coronaviruses are a large family of viruses, of which, there are hundreds, most of which circulate among animals including pigs, camels, bats and cats.  Some of them jump to humans.  Today, there are seven coronaviruses that affect humans, four of which produce mild cold-like symptoms: 229E, OC43, NL63 and HKU1. However, the other three are more serious: SARS (severe acute respiratory syndrome) which emerged in late 2002 and disappeared by 2004; MERS (Middle East respiratory syndrome), which emerged in 2012 and remains in circulation in camels; and COVID-19(SARS-CoV-2).

When researching for this article, I found studies relating to these coronaviruses, where possible.



I personally believe this is the best thing you can do to boost your immune system. A healthy microbiome not only protects against pathogens, it only regulates your immune system and protects against inflammation, as indicated by this study. Each surface of the human body contains microbiota (including the skin) and act as a defence system against pathogens. More specifically, a healthy microbiota minimises the chances of viruses as this study indicates. 

This most recent study mapped the interactions between populations of gut bacteria and the immune system in the human colon. 

To maintain and improve a healthy microbiome eat fermented foods such as:

Bone broth also supports a healthy microbiome.


To perform at our optimum, we need varied nutrients. Eating a wide range of whole foods that are nutrient-dense is an important part of this.  Nutrient-dense foods refer to the ratio of nutrients to calories. Refer to this table for nutrient-dense foods.





Licorice has been found to contain antiviral properties. This review found that licorice contained both antiviral and antimicrobial effects. It contains two triterpenes,  glycyrrhizic acid and glycyrrhizin which have been reported to have antiviral effects.  It was found that these triterpenes can inhibit the virus gene expression and replication as well as enhance the host cell.  Please note, licorice should not be consumed by patients with hypertension (high blood pressure).

Frankfurt University conducted a study to specifically analyse glycyrrhizin and SARS virus.  Researchers noted that high doses of glycyrrhizin inhibited the SARS virus from attaching and targeting host cells, as well as prevented it from replicating.

However, licorice is known to have side effects when consumed in large doses, over a long period of time. Side-effects include cardiac dysfunction, edema (fluid retention), and hypertension (high blood pressure).

Suggested uses: Licorice is available in many forms. As with all foods, I suggest finding a form that is as close to natural as possible to ensure all the beneficial phytochemicals are retained. For example, licorice root tea is available from health food stores.


Oregano contains a phenol called carvacrol which has been found to have antiviral properties. This study found that oregano oil inhibited the murine norovirus (MNV) which affects mice.   Research is typically conducted on MNV since it is similar to the human norovirus which is very difficult to replicate in a laboratory.

This Brazilian study indicates that oregano oil exhibited antiviral activity against several viruses including herpes simplex virus type-1; rotavirus, and respiratory syncytial virus.  Researchers indicated that the best effect was if oregano oil was taken both before and during infection.

Suggested uses: Oregano oil can be purchased at your health food store. Simply add a couple of drops into your glass bottle of water. Add fresh oregano to your cooking or drink as a tea.  However, heating may dilute its efficacy.


This review indicates that echinacea (Echinacea purpurea) could treat numerous viruses including SARS.

In this randomised placebo study, 755 participants were studied over 4 months and it was found that the echinacea group were 58% less likely to fall ill. Interestingly, the best results were found with membranous viruses, such as coronavirus, parainfluenza virus, and influenza virus.

Suggested uses: Echinacea is easy to purchase in at your local health food store. I recommend buying the organic liquid form and gargling.  It’s not a pleasant process and it numbs your throat but it works.  Coronavirus enters through mucous membranes and starts in the upper respiratory area, so it makes even more sense to me.


This study indicates that elderberry (Sambucus nigra is its botanical name) stem extract can inhibit the replication and viral attachment of Human coronavirus NL63.

These researchers studied its effect on the chicken coronavirus and suggest taking it at the early stage of the infection, suggesting it may render the virus non-infectious.

Suggested uses: It is possible to purchase elderberry from health food stores in many forms.  However, processing may destroy the benefits.  This study suggests that herbal infusions and syrups (undiluted) are the best forms.  As with everything, I believe in choosing the less-processed product. Unfortunately, I couldn’t find any tinctures or cold-pressed juices. antiviral foods - elderberry teaI found a tea which also had echinacea. However, I doubt the quantities are sufficient to make a difference.  It does taste great though!

A better alternative is to buy the dried elderberries, which I found online at the site also has a recipe to make the syrup which you can find here


You have probably heard of green tea’s antioxidants effect. It also contains flavonoids and polyphenols. Up to 25-35% of green tea is polyphenols.  One, in particular, known as catechins provide green tea with its antiviral properties by disrupting the virus’ replication cycle. The green tea is a product of the plant Camellia Sinensis. You may recognise this is the plant is of the same genus as the Camellia Japonica mentioned above.  This review of nearly 100 studies outlines green tea’s antiviral activity. Researchers analyse green tea’s ability to inhibit the Bovine coronavirus and indicate that its efficacy is higher in the intestinal tract where the temperature is 37 degrees Celcius.


As you might guess, there are several studies referring to Chinese herbs coming out of Asia.  Below are those I found that specifically relate to SARS and MERS. 

Please note: herbs are not suitable for everyone and can contradict some medications. In addition, some herbs can be toxic if ingested in large quantities. Therefore, please do not take herbal treatments unless prescribed by a herbalist.

One study published in 2014 looked at herbs that can have an inhibitory effect on coronavirus, specifically SARS and MERS. They noted the following herbs:

This review also confirmed the three herbs above prevented the early stage of the coronavirus 229E  infection, including viral attachment and penetration. 

This study conducted in 2016 found the following plants had inhibitory effects on coronavirus. In this case, it was MERS and PEDV (swine flu) strains

This study found four herbs that contained compounds with antiviral properties against coronavirus SARS.

  1. Artemisia annua
  2. Lycoris radiata
  3. Pterostylis lingua
  4. Lindera aggregata

This Chinese study reviewed hundreds of Chinese medicinal herbs and identified the following herbs as having a moderate to potent antiviral effect against SARS:

Another Chinese study outlined Houttuynia cordata following herbs as a natural inhibitor against SARS 

This study identified Isatis tinctoria, also called woad, dyer’s woad, or glastum as having a natural inhibitor against SARS 

This study identified Torreya nucifera as a natural SARS inhibitor 

To my knowledge, none of these herbs are readily available to the average person in Australia.  Should you wish to pursue the purchase of these herbs, I suggest visiting a herbalist. Which as I mentioned above, is always recommended when administering herbs to ensure proper use and dosage.  However, even though it may be difficult to obtain some of these herbs, I wanted to include them since some of the best results were obtained from these Chinese herbs in laboratory tests.




Cloves contain the phenolic compounds of eugenol, eugenol acetate and gallic acid and are one of the richest sources of these polyphenols. This study investigated six foods: flower buds of clove, fenugreek seeds, garlic and onion bulbs, ginger rhizomes, and jalapeño peppers were tested for antiviral activity. The star performers were cloves and ginger.

Suggested uses: Cloves are delicious used whole in cooking or chai tea. However, not, excessive eugenol might slow blood clotting.  Slow blood clotting may increase the chance of bruising or bleeding.


A study of fresh and dried ginger against human respiratory syncytial virus indicated that fresh ginger was able to decrease plaque counts to 19.7% and 27% and was most effective when given prior to exposure to the virus. Plaque counts are a way of determining virus strength and the rating systems is 10 to 100.  Specifically, high quantities of fresh ginger given prior to exposure could decrease plaque counts to 12.7%.

 Suggested uses: Slice or chop peeled fresh sliced ginger in tea or cooking, however, try to reduce heat damage.


Cassia Cinnamon contains coumarin which has been found to contain antiviral properties. Researchers found that coumarin can target various enzymes and pathways that are essential for viral entry, survival and infection. 

However, high quantities of coumarin can negatively affect your liver. How much is too much?  (0.1 mg/kg per day). Which equates to approximately 5mg (2 teaspoons) for an average 59Kg person.  

Suggested uses: Cinnamon powder or stick form can be used in either chai tea or general cooking.  For chai tea, pound cinnamon stick with mortar and pestle to make chai spices for tea.


Turmeric contains the polyphenol curcumin. This study investigated turmeric’s antiviral properties on enteric coronavirus (porcine epidemic diarrhea virus) and concluded that curcumin can prevent the entry and replication of the virus by changing the structure of the viral protein. 

However, curcumin is susceptible to degradation at high temperatures, in addition, it has poor bioavailability.  Therefore, to ensure you are obtaining all the beneficial properties of curcumin from turmeric, do not cook at high temperatures for a long period of time. To improve bioavailability use in conjunction with black pepper, this increases curcumin’s bioavailability by 2000% according to this study.  In addition, use in conjunction with fats (I suggest milk or coconut oil), as indicated in this study

Suggested uses:  A turmeric latte with ginger and coconut oil and honey is delicious, add some cinnamon and cloves for extra antiviral properties!




This study indicates that plant terpenoids and lignoids have inhibitory effects on SARS. Examples of plant terpenoids are:

  • Cannabis
  • Ginkgo biloba
  • Turmeric
  • Mustard seed 



This Chinese study identified the flavonoid Kaempferol as having an antiviral effect on SARS coronavirus. Kaempferol foods include

  • kale
  • rocket
  • watercress
  • mustard greens

This study that found quercetin has antiviral activity against SARS. Quercetin can be taken as a supplement. However, I always prefer foods to supplements.  You can find quercetin in the following foods:

  • capers (careful of the sodium content when packaged)
  • coriander
  • radicchio
  • okra

Quercetin can be easily found in supplemental form.


The same study that found quercetin, also found that luteolin displayed inhibitory activity for the entry process of SARS into host cells.  Foods containing luteolin are:

  • radicchio
  • Mexican dried oregano
  • green capsicums
  • globe artichokes

Luteolin can be found as a supplement.  Currently, Chemist Warehouse has the Blackmores supplement on sale



This recent research from the University of Seoul reviewed several flavonoids against the SARS virus. They also included Kaempferol (listed above) and found herbacetin, rhoifolin and pectolinarin were the most inhibitory against the SARS virus.

You can find herbacetin in flaxseeds.  Rhoifolin comes from citrus peel and found in highest concentration in grapefruit and pummelo. Pectolinarin is a Chinese herb and difficult to source.



Myricetin is a flavonoid and antioxidant. Researchers from the University of Seoul found that both Myricetin and Scutellarein inhibit the SARS in vitro (in a test tube).  Foods high in Myricetin are

  • cranberries
  • swiss chard
  • green hot chilli
  • garlic

Scutellarein can be found in the herb Scutellaria lateriflora




The same study that identified luteolin and quercetin above also identified TGG as displaying inhibitory activity for the entry process of SARS into host cells.  Unfortunately, TGG is predominantly a Chinese medicine and I am unaware of how to source it in Australia.


Many studies point to the medicinal properties of mushrooms. This review looked at over 150 studies of mushrooms to see if there are pharmacological possibilities to develop an antiviral medicine. However, standard button mushroom may not be the answer. More exotic mushrooms such as mitake (hen of the woods), scaly wood and shitake which have more beta-glucans which are known to be antiviral and antibacterial.

What about cooking? When cooking methods were studied, it was found that the antioxidant level in mushrooms was reduced when boiling and frying but increased when grilled. However, conversely total glucans, which is the antiviral property in mushrooms, increased when boiled.

Suggested uses: mushroom soup with exotic mushrooms described above.


Garlic has been used for centuries to ward off illness. It contains a compound called alliin which has been found to regulate your immune system Research indicates that it could assist with colds and flu. Specific to coronavirus, this study indicates that garlic had inhibitory effects against coronavirus in embryonic chickens. 

Note, the way you cook with garlic may inhibit the alliinase enzyme (which converts to alliin).   This study indicates that heat destroys the allyl sulphur compound. However, it goes on to say that if you crush or slice garlic which increases the alliinase enzyme, then let it stand for 10 minutes this may reduce the negative effects of heating. Researchers also suggest increasing the quantity in meals. 

Suggested uses: chimichurri is a great condiment to accompany deep water fish since the coriander and parsley chelates heavy metals which are found in deep water fish.  It also uses raw garlic, so it is particularly effective as an antiviral.





This study indicates that Vitamin A plays a role in immunity and fighting viruses

Whereas, this study specifically notes coronavirus and indicates that Vitamin A and Vitamin D work together to fight viruses, noting coronavirus as an example of a virus.

High sources of vitamin A foods include:

  • Cod liver oil – make sure you buy cold-pressed oil to ensure no degradation during processing
  • Animal liver – also a very nutrient-dense food, a great choice.  I make organic liver pate with organic butter and ghee which also have vitamin A.
  • Eggs (choose pasture-raised)
  • Goats cheese

There are no plant sources of vitamin A.  However, if our body is working optimally, it will convert carotenoids into vitamin A.  The  carotenoids, beta-carotene and alpha-carotene and collectively known as provitamin A.  Sources of provitamin A are:

  • Sweet potato
  • Kale
  • Butternut pumpkin 


There are conflicting studies on the efficacy of vitamin C with viruses.

However, without a cure for COVID-19 (SARS-CoV-2), Chinese doctors are conducting a study into Vitamin C.  The current study conducted by Zhongnan Hospital in China is to determine if high doses of vitamin C may prevent cytokine surge caused by sepsis of the COVID-19 (SARS-CoV-2). They refer to this study where students were divided into two groups: 463 in the control group, aged 18 to 32 and 252 in the test group, aged 18 to 30.  When symptomatic, the test group were given hourly doses of 1000 mg of Vitamin C for the first 6 hours and then 3 times daily thereafter. Those not reporting symptoms in the test group were also administered 1000-mg doses 3 times daily.  the difference between the test group reported 85% fewer symptoms compared to the control group.

Foods high in vitamin C are:

  • Capsicum
  • Citrus fruits
  • Kiwi fruit
  • Papaya

Vitamin C is destroyed with heat. Therefore, eat vitamin C rich foods raw. 

Suggested uses: I normally recommend foods over supplements, however, in this case, I will make an exception.  If I was symptomatic, I would administer 3-40000mg on the first onset of symptoms, followed by 1000mg of vitamin C every hour for the first day, then 1000mg, 4-6 times per day whilst you are symptomatic.


This in-vitro study (not tested on a live being) indicates that zinc can inhibit the replication of SARS-coronavirus in cell culture. 

Please note the maximum zinc intake recommendations from the Australian National Health & Medical Research Council below. UL is the upper limit





This study indicates that antioxidants may play a role in the treatment of viral infections.

Infections and viruses trigger oxidative stress. Macrophages (immune cells) fight off viruses and produce free radicals as a normal by-product of this process. However, under normal circumstances, free radicals are eliminated when the infection disappears. However, if the body was already under oxidative stress, this can exacerbate the situation.

This study indicates that nutritionally induced oxidative stress limits the body’s ability to fight viruses.

Read more about oxidative stress in my article on antioxidants and oxidative stress. Second to a healthy microbiome, this is my next area of focus for a healthy immune system.


Most of these studies were conducted with natural extracts of the antiviral foods. It is not always possible to obtain natural sources of antiviral foods, however, please always try to obtain the closest form to the organic whole food. Pills, powdered and processed forms are not close to natural. Of course, at times of short supply, you might not have a choice. But if you do, choose organic, whole natural foods every time. This goes for all types of food. Read my article on healthy nutrition here and convenient meal preparation here. Not all foods need to be organic all the time if you are experiencing budget or supply issues.  Check the list of foods that need to be organic here.

Cooking methods are discussed in each of the antiviral foods’ descriptions above. As a generalisation, most phytochemicals (which in most cases are the active compounds that provide the antiviral properties) are destroyed by heat.  Therefore reduce the temperature and duration of cooking. For example, I use tea forms of many of the antiviral foods.  When preparing the tea, I put room temperature water on the tea first, then add boiling water so the antiviral foods are not hit with boiling water.

After researching all the studies, here is what I will be doing to incorporate these antiviral foods into my life.  Everyone is different and you can make your own decisions as to what you would like to do. However, please bear in mind the indications associated with each of the antiviral foods in the article. Not all antiviral foods are suitable for everyone.

Licorice tea or all-natural licorice confectionery (beware of added process sugars).  I will be going with organic licorice root and using it as a tea.

Oregano – oregano oil can be found in most health food stores. A  couple of drops in my bottled water (glass bottle). I have bought pots of herbs from Harris Farm (they can be found in many outlets). I add fresh oregano to my cooking and drink as a tea.

Echinacea – purchase organic liquid from the health food store and gargle on the first sign of sore throat.

Elderberry – I was unable to find fresh berries. I am unaware of where to purchase them from. However, I found organic elderberry liquid online.

Green tea – Organic loose leaf green tea to make into spice tea (see below). Also with ginger and lemon (add after the tea has cooled)

Cloves – Organic cloves to use in chai tea (see below) cooking etc.

Turmeric – each morning I add a heaped teaspoon to bone broth (include the fat) with black pepper, chilli, ginger and lemon and enjoy as a drink. alternatively, make a turmeric latte with warm milk, turmeric, ginger, black pepper, coconut oil.

Notes: Try not to boil or expose turmeric to heat for too long as this destroys the antiviral curcumin.  To enhance the bioavailability of turmeric’s curcumin by 2000%, always add back pepper. Add fat to further increase bioavailability (for example, milk, coconut oil, fat in bone broth).

Chai Spice Tea – buy organic spices such as cloves, cinnamon stick, cardamom pods, allspice berries, star anise and pound with mortar and pestle to create a spice mix.  Mix with loose leaf green, licorice and elderberry tea.

Kaempferol, luteolin & quercetin foods – foods that I will increase in my diet – kale, rocket, radicchio, capers (careful of salt), watercress, green capsicum (also high in vitamin C so I eat them raw in a salad), globe artichokes, silverbeet, green chillis, garlic

Supplements – Personally, I am not normally a fan of supplements. I believe in obtaining nutrients from foods. However, in these abnormal times, when our bodies may be under abnormal duress, this is what I will be doing. You can make your own decisions. I will be taking high doses of vitamin C (as I indicated in the vitamin C section above). In addition, I will be supplementing with zinc (without going over the limits outlined) Quercetin and Luteolin.  Refer to the appropriate sections for details.



The World Health Organisation (WHO) renamed COVID-19 to SARS-CoV-2 on February 11 and stated:

This name was chosen because the virus is genetically related to the coronavirus responsible for the SARS outbreak of 2003.  While related, the two viruses are different. 

Therefore, in summary, I would pay particularly close attention to those six antiviral foods which have been shown to have inhibitory effects on SARS.  Those are, in order of ease of supply and use:

  1. Quercetin – use supplements in these abnormal times
  2. Luteolin – use supplements in these abnormal times
  3. Zinc – use supplements but adhere to limits
  4. Licorice – use in moderation (see notes above)
  5. Terpenoid phytochemical found in
    • Cannabis
    • Ginkgo biloba
    • Turmeric
    • Mustard seed
  6. Kaempferol flavonoid found in
    • kale
    • rocket
    • watercress
    • mustard greens
  7. Chinese herbs listed that are hard to come by

In addition, Chinese doctors are studying vitamin C specifically for COVID-19 (SARS-CoV-2). Therefore, I will also be supplementing with vitamin C.

I hope this helps!

Stay tuned for the next article on coronavirus stress tips. Join the newsletter to get notified when it is published. You can sign up below.

On a final note, please practice social distancing, if you must leave your home. Otherwise, please stay at home, for the sake of you and your community.

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