Since the beginning of the pandemic, health organizations and experts have been struggling to contain the spread of fake news and myths surrounding alleged "miracle cures" for COVID-19, suggesting, for example, that consuming garlic or lemon could prevent the risk of infection. 

While these myths were busted, scientists across the world have actually turned to fruits, herbs, and vegetables with renowned therapeutic qualities to examine whether they could be helpful in the fight against COVID-19. 

Because, although no food has proved to be able to cure or prevent COVID-19, a healthy immune system and proper nutrition are fundamental in keeping us well in these challenging times and could be a precious defense, alongside social distancing, hand washing and vaccines, against the virus.

Plants have been used for centuries in almost all cultures across the world as natural remedies to treat chronic infections, including viral diseases. More than 2,500 years ago, the father of western medicine, Hippocrates, said: "Let food be thy medicine and let medicine be thy food."

The introduction of important medicinal food plants in the general public's daily diet could be an easily achievable game-changer in the fight against viruses and diseases, strengthening and improving people's immune system and overall health.

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Below, you can find a summary of the compounds from fruit, vegetables and herbs that have proved more promising in tackling SARS-CoV-2.

Although none of these natural remedies can replace medicines, these substances have the potential to engage with the virus in a way that could be a relief for patients and lighten the burden for health care system struggling with high numbers of infections.

Pomegranate

A study conducted by researchers at the University of Banja Luka in Bosnia and Herzegovina found pomegranate polyphenols extracted from peels of pomegranate fruit can play a role in inhibiting coronavirus infection.

Those extracts have previously shown to have beneficial effects for other diseases such as type 2 diabetes, cardiovascular diseases, atherosclerosis, inflammatory diseases and even some types of cancer. Most importantly, they have shown significant antiviral activities against some viruses other than SARS-CoV-2, preventing influenza virus entry and RNA transcription.

Based on these premises, the scientists at the University of Banja Luka are currently researching whether pomegranate could be an aid to treating and preventing COVID-19.

"It's a long way to say it's a drug, or it could stop SARS-CoV-2 infection," said research leader Relja Surucic, who warned it would be an exaggeration to call pomegranate a cure for COVID-19. However, he thinks it has the potential to be used as a complementary treatment or a supplement to treat the infection.

Ginger

"Enjoy ginger, but it's not a 'cure' for COVID-19", the World Health Organization (WHO) let the public know during the first wave of COVID-19 back in 2020. 

As the theory that ginger could help cure COVID-19 started circulating online among other such 'social media remedies', the WHO informed that while natural remedies such as ginger can have a "positive impact on your health," they are by no means a medically proven treatment for fighting COVID-19. 

But the idea that ginger can boost energy levels and the immune system and relieve the symptoms of other diseases, such as a cold, is rooted in its actual medicinal properties. Ginger is a natural anti-inflammatory and antioxidant, used for centuries not only as a spice, but also as a herbal medicine to relieve pain, nausea and vomiting.

A systematic review analyzing all clinical studies on the efficacy of ginger in treating different conditions (including nausea, gastrointestinal function, pain, inflammation and metabolic syndromes) found that in the majority of cases, ginger showed to be effective in alleviating symptoms of each condition. 

But the quality of the trials was admittedly inconsistent, and more research is needed to understand the real beneficial properties of this 'wonder root' and whether it could prevent or efficiently treat COVID-19.

Dandelion

Dandelion, a plant that can grow naturally in meadows or open fields amid weed and grass, is one of the many plants scientists are testing for potential use against COVID-19. 

A study conducted by scientists in Freiburg, Germany, found evidence that the common dandelion (Taraxacum officinale) is able to block interaction between the spike S1 protein and the human ACE2 cell surface receptor in vitro (the protein on the surface of many cells the virus attach itself to).

Another study looking at data coming from Sweden and the UK, both consumers of dandelion as food, concluded that the plant has proven useful for medical use against COVID-19.

Although we still know very little about dandelion effects on health, dandelion root has recently also been studied for potential use against cancer, with promising results in prostate and breast cancers.

Curcumin

Curcumin, a natural compound found in the spice turmeric, is another promising herb scientists are looking at. A study published in the Journal of General Virology found that curcumin can prevent infection from Transmissible gastroenteritis virus (TGEV), a coronavirus that infects pigs. 

Curcumin has also been shown to inhibit the replication of viruses including dengue virus, hepatitis B and Zika virus.

In the context of COVID-19, several studies have shown that curcumin can hinder cellular entry and replication of SARS-CoV-2, but once again more evidence is needed.

Licorice

Licorice root extract is a well-known anti-inflammatory natural medicine.

A team of scientists in Germany conducted a study analyzing the impact of licorice root extract in neutralizing SARS-CoV-2 in vitro.

What they found is that glycyrrhizic acid, a substance which is found in high concentrations in licorice roots, acted as an active antiviral ingredient and it exhibited antiviral activity against many viruses, including herpes simplex viruses, the human immunodeficiency virus (HIV), and human and animal coronaviruses.

Another study conducted in Egypt and reviewing clinical trials on the beneficial effects of licorice root around the world came to the same conclusion as the German research, showing that glycyrrhizin and licorice extract have the capacity to disrupt the virus' entry into the host cells.

The German study has not been peer-reviewed yet, so it cannot be considered conclusive. But the scientists are positive that glycyrrhizic "potently neutralizes SARS-CoV-2 by inhibiting the viral main protease" and they suggest more studies should follow to further investigate this potential antiviral compound as a treatment for COVID-19.

Thyme, ivy, primrose and more

Another study conducted by the same team at the University of Freiburg in Germany who looked at dandelions, analyzed how five herbal medicinal products interacted with the virus and could potentially help treat the symptoms of COVID-19. 

The herbal extracts studied were bronchipret thyme-ivy (an extract of thyme herb and ivy leaves), bronchipret thyme-34 primrose (an extract of thyme herb and primrose root), imupret (an extract including, among others, chamomile flowers, dandelion herb and oak bark), sinupret extract (containing verbena herb, sorrel herb, primrose and elder flowers and gentian root) and tonsipret (normally used in tonsillitis tablets). 

Results derived by in vitro screenings showed that the extracts could activate defense mechanisms in the cells exposed to the virus.

In the case of the extracts including thyme and ivy, thyme and primrose and imupret, these had the ability to interfere with various steps of the viral replication cycle by inhibiting the binding of the SARS-CoV-2 spike S1 protein and the human ACE2 receptor, identified as the key cellular receptor facilitating uptake of the SARS-CoV-2 virus into the host cell.

The catch? The concentration of these extracts which is able to inhibit interaction between the virus and the host cell is highly toxic to humans. 

But not all research was in vain: both imupret and the combination of thyme and primrose root extract showed to be able to trigger an immune defense response at a lower concentration that is safe for people. It might be a matter of fine-tuning the concentration of the herbs in the extracts.

Despite positive evidence, more research is needed to confirm the beneficial effect of these herbal medicines against COVID-19 – and whether they could be useful for patients at all is still to be tested.