Foods with antiviral properties

Compromised immune systems can put people at greater risk of various diseases—including viral infections. One emerging area of research is the use of functional foods to beef up the immune system. Functional foods facilitate the immune system’s capability to guard against and control pathogenic viral infections, according to the authors of a review published in Nutrients.

"Functional foods and nutraceuticals within popular diets contain immune-boosting nutraceuticals, polyphenols, terpenoids, flavonoids, alkaloids, sterols, pigments, unsaturated fatty-acids, micronutrient vitamins and minerals, including vitamin A, B6, B12, C, D, E, and folate, and trace elements, including zinc, iron, selenium, magnesium, and copper," the authors wrote.

Let’s take a closer look at seven functional foods that fight viral infections.

Olive oil

Olive oil is full of monounsaturated fatty acids, as well as several polyphenols such as oleuropein and hydroxytyrosol, which offer viral protection in the form of antioxidative and anti-inflammatory factors. Of note, these properties are strongest in extra virgin olive oil.

Oleuropein has demonstrated antiviral properties against respiratory syncytial virus, due to its main fragment elenolic acid. Elenolic acid also protects against herpes, influenza, and parainfluenza viruses. Moreover, the antioxidant capacity of olive oil is exerted independently of its antiviral effects.

The authors of the aforementioned review wrote that "hydroxytyrosol antiviral mechanisms were shown through its inactivation effects on influenza A viruses, especially during the virus morphological changes, such as the presence of a viral envelope which is an integral membrane protein involved in several aspects of the virus life cycle including its assembly, budding, and pathogenesis."

Intriguingly, hydroxytyrosol found in olive oil can also have preventative effects on HIV from entering the host cell and binding to the HIV-1 catalytic site, thus stymieing both viral entry and integration.

Cyclotide-containing foods

Plant cyclotides are found in pumpkin, squash, zucchini, legumes, and more. Due to their stable structure, these compounds have been researched extensively to help develop antiviral drugs.

The ability of plant cyclotides to protect against viruses and other pathogens is suggested to be secondary to the prevention of immune-cell malfunctioning. This inhibition occurs with lymphocytes, thus mitigating the over-reactivity of the immune system’s defense machinery.  

Vitamin D-containing foods

Vitamin D found in dairy has recently gained much attention for its ability to battle COVID-19 and influenza infections. 

Different mechanisms explaining the antiviral effects of vitamin D have been postulated. First, vitamin D could lower viral replication rates and prevent lung infection via anti-inflammatory cytokines. Second, the intake of vitamin D could address deficiency, which has been shown to play a role in acute respiratory distress syndrome.

Garlic

This delicious bulb contains many compounds that fight viruses, including allicin, diallyltrisulfide, ajoene, and quercetin. Mechanisms of antiviral action include hindrance of viral attachment to the host cell and alterations in the transcription and translation of the viral genome, as well as interference with viral assembly. 

Garlic exerts activity against influenza A, herpes simplex virus (HSV), and human cytomegalovirus.

Black pepper

The active ingredient piperine is responsible for the antiviral properties of black pepper. It inhibits the entry of viruses by blocking glycoprotein synthesis. 

Black pepper is active against various viruses including coxsackievirus, vesicular stomatitis, and human parainfluenza virus.

Mushrooms

The active ingredients found in mushrooms include polysaccharides and terpenoids. They inhibit the binding of HIV-1 protease and its reverse transcriptase activity. 

Other viruses that mushrooms protect against include influenza A and cytomegalovirus. 

Yogurt

This probiotic mitigates the adsorption and internalization of viruses into cells. It supports the production of metabolites marked by antiviral effects.  

Furthermore, the active compounds found in yogurt facilitate immunomodulation to promote viral protection. Yogurt provides protection against the influenza virus, as well other RNA viruses.

Bottom line

Even with an expanding pool of drugs to treat viral infections, pharmaceuticals can help only so much. Drugs cannot protect against all the viruses in the environment. Diet can be an inexpensive and effective way to help prevent viral illnesses. Moreover, active compounds found in plants can inform the development of antiviral drugs.