What Science Says You Should Know About Tea and COVID-19

What Science Says You Should Know About Tea and COVID-19

 Author: Millennia TEA’s Official Science Steeper, Allison Tannis M.Sc., RHN

10 Best Nutrients to Eat During the Pandemic, According to Researchers


You sip that cup of tea, brewed with your fresh tea leaves, knowing it has a long list of benefits, with scientists saying you should know it may include helping your body outsmart the pesky COVID-19 virus (officially called SARS-CoV-2). With no drug approved to treat COVID-19, scientists have been looking for naturally derived molecules that have known antiviral properties. Certain nutrients, called polyphenols, such as epigallocatechin-3-gallate (EGCG), are on the list of potentially helpful nutrients to eat during the pandemic, according to researchers. In a recent scientific review, published in the peer-reviewed journal, Phytomedicine, the famous polyphenol of green tea leaves, EGCG, could be a potential candidate to prevent, or perhaps in the treatment of COVID. By no means is EGCG a proven preventative, or treatment for COVID-19. However, if you enjoy steeping in science, here’s what researchers know so far about tea and COVID-19. And, where to find other nutrients scientific research is showing is good to eat during the pandemic.


What is EGCG?

Epigallocatechin gallate (EGCG) is one of the most abundant polyphenols found in the leaves of the tea plant, Camellia sinensis. EGCG has been tested for its antiviral activity against several viruses. For example, a virus with some similarities to COVID-19, which is a problem in the pig industry, called PRRSV, wasn’t able to infect the pigs when scientists administered EGCG either prior to, or after exposure. Newer research is investigating EGCG’s potential role against COVID-19 (SARS-CoV-2). Let’s steep into the EGCG research a bit to see what scientists know so far.

Could EGCG Prevent COVID-19?

Science isn’t sure yet. What scientists do know is that in order for a virus to enter a cell in the body, it has to bind to a receptor. EGCG blocks the COVID virus from infecting a cell at the entry step. It does this by interfering with how the virus’ spikes connect with the receptor sites on human cells. One can imagine EGCG acting like a giant piece of gum jammed into the keyhole in your front door, preventing a key (the virus’ spike) from gaining entry to your home. (Researchers would elaborate that analogy to explain in more detail that EGCG interferes with the engagement of the binding part of SARS-CoV-2 viral spikes to the receptor called angiotensin-converting enzyme-2 receptor on human host cells). But, that’s the sort of elaboration you probably won’t use as a conversation starter on your next Zoom meeting.



EGCG May Deter SARS-CoV-2 Says Research

Scientists have reported that EGCG can hamper another key tool the COVID virus needs to survive and cause illness. EGCG reduces an enzyme the COVID-19 virus needs to replicate itself. To better understand, know that once inside a human cell, viruses use the cell’s machinery to make more copies of the virus. It’s sort of like turning your body’s cells into a manufacturing factory for viruses. In order to successfully make a new virus-cell, enzymes called proteases are needed. Essentially, science is suggesting that it appears EGCG can hinder the SARS-CoV-2 life cycle, making it harder for the virus to use the body as a manufacturing plant and inducing illness. Whether or not this works in real-life scenarios is yet to be confirmed by researchers.


Polyphenols and COVID

Scientists are interested in a number of polyphenols with anti-viral abilities to see if they could potentially help fight infection by SARS-CoV-2 behind the COVID-19 pandemic. Many of these polyphenols you may be familiar with:

  • Curcumin (turmeric/yellow curry)
  • EGCG (fresh tea leaves/green tea)
  • Hesperidin (citrus fruits)
  • Resveratrol (purple grapes/red wine)


Does Drinking Green Tea Prevent COVID?

EGCG (found in high amounts in fresh tea leaves) has the potential to help fight off viruses, according to laboratory investigations. But, does it work in humans? There’s no conclusive evidence to suggest it will. However, when SARS-CoV-2 infected cells in a laboratory were treated with EGCG the results were good: a team of scientists looked at EGCG’s anti-viral ability in human lung cells that were infected with SARS-CoV-2 and found the virus was suppressed. Of note, the study looked at cells infected with a variety of SARS-CoV-2 variants of concern, at that time in history. Interestingly, the most effective results happened when the human cells were exposed to EGCG prior to infection. It might suggest that EGCG may be a nutrient with potential benefits during the pandemic.





Best Things to Eat to Boost Immune System during COVID-19

Good nutrition is important in supporting the immune response – it’s scientifically proven. Yet, which are the best things to eat during the pandemic? It’s probably no surprise that the best thing to eat to boost immune system health during COVID-19 is the same list of healthy foods you’re used to reading about (vegetables, fruit, nuts, seeds, beans, whole grains).


What Nutrients are Most Helpful Against SARS-CoV-2?


Vaccines, hand-washing, masking, and physical distancing are measures you can take to reduce the risk of transmission of COVID-19. There is no cure for COVID-19. For your body to produce immune cells, create antibodies, and coordinate immune responses certain essential nutrients are needed. Here’s a list of nutrients scientists say you should know about as they are required to mount an immune reaction to any infectious pathogen and what foods you can find them in:

  • Copper: mushrooms, potatoes, cashew nuts, sunflower seed kernels, dark chocolate.
  • Fibre: Eat more plants (seeds, nuts, whole grains, vegetables, fruit) as it promotes diverse gut microbiota (probiotics).
  • Iron: white beans, dark chocolate, lentils, spinach, firm tofu, kidney beans, chickpeas.
  • Selenium: tuna, halibut, brazil nuts, turkey, brown long grain rice, egg, whole wheat bread.
  • Vitamin A: salmon, green leafy vegetables, squash, carrots, broccoli, mangoes, apricots.
  • Vitamin B6, B9 (folate), B12: chickpeas, salmon, leafy greens, potatoes, banana, nutritional yeast, bulgur.
  • Vitamin C: kiwi, raspberries, citrus, bell peppers, broccoli, cauliflower, tomato.
  • Vitamin D: trout, mushrooms, salmon, fortified plant-based dairy alternatives.
  • Vitamin E: wheat germ, sunflower seeds, almonds, nut butter, spinach.
  • Zinc: oysters, crab, baked beans, fortified cereals, pumpkin seeds.


Good nutrition supports the immune response. Eating healthy foods can also promote a robust response to vaccination. For more up-to-date information about COVID-19 visit the Center for Disease Control (CDC), or the Health Canada COVID-19 website.






Epigallocatechin gallate from green tea effectively blocks infection of SARS-CoV-2 and new variants by inhibiting spike binding to ACE2 receptor. Cell Biosci 2021 Aug 30;11(1):168.


Antiviral activity of green tea and black tea polyphenols in prophylaxis and treatment of COVID-19: A review. Phytomedicine 2021 May; 85: 153286.


Multiple antiviral approaches of (-)-epigallocatechin-3-gallate (EGCG) against porcine reproductive and respiratory syndrome virus infection in vitro. Antiviral Res 2018 Oct;158:52-62.


EGCG, a Green Tea Catechin, as a Potential Therapeutic Agent for Symptomatic and Asymptomatic SARS-CoV-2 Infection. Molecules 2021 Feb 24;26(5):1200.


Potential protective mechanisms of green tea polyphenol EGCG against COVID-19. Trends Food Sci Technol 2021 Aug;114:11-24.


Nutrition and immunity: lessons for COVID-19. European Journal of Clinical Nutrition 2021 June;75(1309-1318.