Functional Foods That Protect Us From Viruses

Functional Foods That Protect Us From Viruses

Cold and flu season is upon us again, and it is time to have another look at what steps we can take to protect ourselves during the winter months.  Of course, the most worrisome of the viral diseases right now is still COVID-19, though currently there appears to be a new wave of RSV (respiratory syncytial virus) that is generating some alarm.


Last year, BC Children’s Hospital reported nearly three times the usual number of RSV infections in kids under 3. Other provinces, such as Alberta, also had a higher-than-usual number of RSV-related hospitalizations. By many accounts, this year is shaping up to be worse for children’s hospitals, according to nearly a dozen pediatric specialists interviewed by The Globe and Mail.” (Source)

RSV is a virus that infects the lungs and airways and, while it can affect anyone of any age, it most commonly occurs in infants and young children. Although the media is touting this virus as the next new virus of major concern, it is, in fact, so common that by the age of three, almost all children have been infected with RSV.  Even the CDC (Center for Disease Control and Prevention) downplays this ailment: “RSV is usually a mild disease that goes away on its own in a week or two.”

However, “in very young children RSV can sometimes lead to serious infections like pneumonia or bronchiolitis (a swelling of the bronchioles — the smallest air passages of the lungs)”.   (Source)

That being said, “there is no specific treatment for RSV infection”, therefore in such cases one is best advised to turn to the wide range of natural anti-viral and immune-supportive agents discussed in previous newsletters, and to be discussed in this one.


This newsletter amounts to an overview and summary of a long meta-analysis of data from around the world, accumulated during the COVID years.

This study is titled, “A Review on the Antiviral Activity of Functional Foods Against COVID-19 and Viral Respiratory Tract Infections”, and was published in the International Journal of General Medicine, in May of this year.

In this review, the researchers “presented the relevant data which originated from trusted publishers regarding the practical benefits of functional foods (FFs) and their dietary sources, in addition to natural plant products, in viral respiratory and COVID-19 prevention and immune-boosting activities”.

As well as looking at functional foods, this particular meta-study also covers certain nutrients proven to fight viral infections, either with direct action or via the immune system. These nutrients (vitamins A, C, D, E, selenium, zinc, and probiotics) I have addressed in previous newsletters, so herein I will focus primarily on the foods discussed in the study.

Functional Foods

It is no surprise that “the food sector has been affected since the inception of COVID-19, and the demand for functional, organic, and sustainable foods has increased”.  Which may be the only good thing that has come out of this pandemic, for at least many more people are seeking natural alternatives to medical intervention. And, it can only be of great benefit for all of us if these types of foods and herbs grow in popularity, since using functional foods will ultimately reduce the frequency of all diseases.

The term “functional foods” (FF) was introduced in Japan in the early 1980s, and refers to “foods that have disease-prevention and/or health-promoting effects in addition to their nutritional value”.

Since then, many FF have been proven to have antioxidant, antimicrobial, anti-inflammatory, antiviral, and immune-modulating properties. And, many of these previous studies discovered that certain compounds found naturally occurring in common foods were able to suppress coronaviruses similar to COVID, including severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS).

Traditional herbal medicines like teas, roots, mushrooms, and dried plants and leaves, along with olive oils, fish oil, nuts, fruits, and vegetables, are among these functional foods. Most of the products mentioned above contain natural vitamins (such as vitamins A, C, and D) and minerals (like zinc, iron, and selenium), fatty acids, prebiotics, flavonoids and other polyphenols, all of which are particularly immunoprotective due to their antioxidant and anti-inflammatory effects.

Of course, aside from the medicinal properties of these foods, simply eating well is the first step to a strong immune system, which is the first step towards fighting off all viruses. This is why many of those who suffered the worst from COVID, and most often died from it, came from impoverished communities, or were obese (or had pre-existing severe medical conditions). These people most often are those consuming large amounts of bad fats, sugars and refined carbohydrates, and were commonly found to be deficient in vitamin D, zinc, selenium, and other essential nutrients.

Now let’s have a brief look at those functional foods which proved to have the best track record for protecting people from all respiratory viruses.


Elderberry, used in the form of tea, tincture, syrup, or in capsules, is well known to have an antiviral action against the common cold and influenza viruses.  “It was discovered that elderberry juice has a considerable antiviral effect against influenza virus infection in humans when tested on the human IAV (influenza A virus) using concentrated elderberry juice.” This study also “showed elderberry’s antibacterial activity against pathogens responsible for upper respiratory tract infections”.


To quote from the study we are examining: “Studies demonstrated that flavonoids have an antiviral effect against coronavirus.” Flavonoids, of which there are many kinds, are found in large amounts in apples, berries, cherries, grapes and onions. “They have numerous biologically beneficial activities in the human body, including anti-inflammatory, antioxidant, anti-mutagenic, and antiviral properties.”

Berries, more commonly consumed than elderberries, seem to be one of the best sources of these flavonoids for our purposes. One study “investigated the antiviral action of numerous berry extracts and realized that berry fruit extracts prevented the replication of IAV”.

It should be noted that quercetin, widely used in the natural medicine community for preventing and treating COVID, is also a flavonoid, found at particularly high levels in onions.

Our meta-study also highly recommended the flavonoid naringin which “has the highest binding affinity with spike protein compared with COVID-19 common medications”. By far, the highest source of naringin in the diet is found in grapefruit and grapefruit juice.

While not a food per se, one of the richest sources of a wide range of unusual flavonoids is propolis (a bee-metabolized sticky material from various plant sources, used as a glue in hive building and to keep the hive antiseptic). “Evidence from the literature strongly suggested that propolis and its constituents can be a promising source of pharmacological for prevention and symptomatic treatment in patients infected with COVID-19.”


Known as “Russian penicillin” in WW 2 due to its amazing antibacterial properties, most of us already turn to garlic whenever we have a cold or flu. Thus, it will surprise no one reading this that “garlic and its organosulfur compounds were shown to have antiviral effects against common cold, influenza, and acute respiratory viral infections in various clinical studies”.


Fresh ginger has been found to have antiviral action and is effective against the respiratory syncytial virus (RSV).”


The antiviral action of honey has been well studied, having shown antiviral activity against the Rubella virus, and herpes simplex virus-induced chronic lesions (used topically in this case). “Because of its antiviral properties, this compound will effectively prevent influenza virus replication.

Of the variety of honeys available the most medicinal is Manuka honey, as this other study noted: “Our results showed that honey, in general, and particularly manuka honey, has potent inhibitory activity against the influenza virus, demonstrating a potential medicinal value.”  (Source)

Honey is also of great value for a dry cough, by moistening the lungs allowing them to expel mucous more effectively. In fact, recently it was determined by researchers from Oxford University’s Medical School that “honey was more effective in relieving the symptoms of cold and flu-like illnesses than the usual commercial remedies, and could provide a safer, cheaper and more readily available alternative to antibiotics”.  (Source)

Lemon Balm

Extracts of lemon balm were found to “prevent influenza virus duplication at different steps of the multiplication cycle, specifically during direct interaction with virus particles, also their antiviral action against human immunodeficiency virus type 1 (HIV-1)”.  While available in capsule and tincture form, lemon balm is easy to incorporate into the diet as a herbal tea.


Glycyrrhizin, isolated from licorice, “was the most effective treatment in preventing the multiplication of the SARS-associated virus based on the medication of two clinical isolates of coronavirus from SARS cases hospitalized to the Clinical Center of Frankfurt University in Germany. According to studies, liquorice has high immunomodulation activity and is helpful, especially in improving the body’s immune system’s ability to combat microbial diseases.”

Licorice is also easy to use in tea form, as a regular part of one’s diet, but should be avoided by those with high blood pressure.


“Prebiotics contribute to short-chain fatty acid production that can modulate the immune system by enhancing anti-inflammatory cytokine production and decreasing pro-inflammatory cytokine development.”  And, of course, prebiotics feed good probiotics in the gut, and probiotics have been well established to be essential to a well functioning immune system.

High amounts of prebiotic fibers are found in asparagus, bananas, barley,  beans, dandelion greens, flax seeds, garlic, Jerusalem artichoke, lentils, oats, and onions.  Many prebiotic powders are also on the market, and can easily be added to food or beverages. These include inulin (from chicory root), acacia fiber, and hydrolyzed guar gum.

Prebiotics work in part by producing the short-chain fatty acid butyrate, and perhaps the best source of butyrate in the diet is butter.

Butyrate has been shown to have a role in gene regulation, cell differentiation, immune modulation, regulation of the intestinal barrier, intestinal motility, diarrhea control, and visceral sensitivity.”  (Source)

(Two of our products serve this prebiotic function well: Lactospore and Provide Smoothie Mix.)


Flavonoids are a category of compounds known broadly as polyphenols, and resveratrol is a powerful polyphenol found in grapes, mulberry, peanuts, red wine, as well as in other plants. This substance has antioxidant, anticancer, and antiviral properties, and is of particular value when treating COVID.

The coagulation disorders and thrombotic events are the consequences of COVID-19, which increases inflammatory cytokines. For these reasons, it is speculated that resveratrol, as a natural substance with anti-thrombotic characteristics, could effectively protect against COVID-19. Resveratrol has been reported to significantly inhibit MERS-Coronavirus replication and reduce cell death (25%) after virus infection.”


Curcumin is a flavonoid component of the spice turmeric, one which has shown antiviral properties against numerous viruses.

For COVID-19 management, there is a suggestion that curcumin may have a beneficial effect on viral encapsulation, cytokine storm protection, and cellular signalling pathways by blocking virus entry and viral protease encapsulation. Furthermore, curcumin also alters the structure of viral surface proteins, making it difficult for the virus to enter the host cell.”

(For a shortcut to obtaining the benefits of both curcumin and resveratrol one can use our Liposomal Curcumin/Resveratrol product.)


In conclusion, eat lots of these foods, and maintain a generally healthy diet, and you will be ahead of the game when viruses come looking for you. Or. as Michael Pollan summarized in his book “In Defense of Food”: “Eat food. Not too much. Mostly plants.”

It is Pollan’s definition of “food” that makes this the best and simplest advice we can follow. He discusses in his book how much of what we eat is not really food: “We are eating a lot of edible food-like substances, which is to say highly processed things that might be called yogurt, might be called cereals, whatever, but in fact are very intricate products of food science that are really imitations of foods.”  (Source)

For much more detail on the functional foods we have examined, and for clinical reference points on each, follow this link to the original meta-study.  (Source)

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