I find it interesting that, when investigating viruses, researchers often turn to tea—possibly to drink, but generally as something to analyze.
It’s way too early to know if this will hold true for COVID-19, but here are a few examples of how tea and its abundant polyphenols have been studied and may someday be part of our anti-virus toolkit.
Severe Acute Respiratory Syndrome or SARS coronavirus (SARS-CoV) was first identified in 2003 when it swept through 26 countries in 2002–2003. A couple years later, a team of researchers based in Taiwan screened 720 compounds that were in a natural product library* to see if any of them combated the SARS coronavirus.
Of those hundreds of compounds, only 2 of them inhibited the virus: tannic acid and 3-isotheaflavin-3-gallate. Both of these compounds are polyphenols that are present in tea.
The researchers then looked at different teas and found that pu-erh and black tea extracts inhibited the virus more than did green or oolong extracts. They also looked at additional compounds in tea and discovered that the phenol theaflavin digallate, found in black tea, inhibited the virus (Chen et al. 2005).
The Zika virus, or ZIKV, was first identified in 1947, but then resurged in South America in the past few years, tragically affecting pregnant women who then gave birth to children with microcephaly, as well as causing Guillain-Barré syndrome and other neurologic problems. Currently, there is no vaccine for this virus, although there have been some promising recent studies.
A 2016 study evaluated the efficacy of the polyphenol epigallocatechin gallate (EGCG), found in green tea and therefore labeled a “natural drug,” against Zika virus.
This particular phenol is effective against many viruses because it seems to interact with a host cell’s “lipid envelope, leading to a subsequent destruction of the virus particle” (Carneiro 2016). There’s even some preliminary indication that EGCG crosses the placental barrier and lessens (but not totally eliminates) ZIKV’s effects on an embryo, plus it’s safe for both embryo and mother (Carneiro 2016).
Still, this isn’t a perfect solution. Because EGCG isn’t stable and doesn’t easily permeate membranes, among other issues, it would need tweaking so that it’s available within the human body at a dose high enough to work. Natural compounds extracted from plants often have these problems, plus can degrade when exposed to oxygen (Bayraktar et al. 2017).
To make EGCG sufficiently available, it can be chemically altered it—or it can be encapsulated, the preferred method because it gets the phenol to where it needs to be, in the concentration that’s effective (Bayraktar et al. 2017). Research continues.
A 2015 review of polyphenols found that they show a great deal of promise for preventing and treating flu. Our current treatments for flu are not always adequate, and tens of thousands of people die each year (61,200 during the 2018–19 flu season according to the CDC).
Polyphenols, naturally found in food, and particularly rich in tea, can damp down the replication cycle of viruses, can affect how viruses get into the host cells, and so on, which make them potentially valuable complements to current drugs.
Roodabeh Bahramsoltani and team (2015) recommend that more study be done on nontoxic polyphenols that are known to be effective so that we may better understand how they work against the flu virus. With that knowledge, it’s possible that they “could be used as a skeleton for designing a novel generation of antiviral drugs” (Bahramsoltani et al. 2015).
Well, laboratory tests using extracts from tea are definitely not the same as drinking a cup of tea.
Still, we all know that a plant-based diet is healthy for us. And more and more studies are demonstrating that tea provides measurable benefits, with some going so far as to argue that drinking tea is better than drinking water—although both hydrate, tea contains all those polyphenols that water does not.
I cannot say whether tea has any effect whatsoever against COVID-19, but in light of its overall benefits—including, and perhaps most importantly, simply the enjoyment that I get from drinking tea—I’m filling my cup yet again today.
Besides, things always look better when you’re holding a cup of your favorite tea!
*A note on libraries
There are many such product libraries, with 22 natural product libraries currently listed on the NIH website. “Natural products,” in addition to your expected plant and animal sources, include bacteria and fungi, extracts from natural products, and even synthetic compounds extracted from natural sources.
The advantage of using compounds obtained from such a library?
A large number of compounds are readily available.
And a natural product library specifically?
As we need to develop more drugs to address current needs, some scientists are shifting back to natural products, which fell out of favor with the advent of the pharmaceutical industry.
Some of the advantages of natural compounds?
For one thing, living entities have spent their existence as a species developing protections against infections and infestations—and against being eaten out of existence.
Phytochemicals [biologically active compounds found in plants] also demonstrate far greater structural diversity and complexity than the relatively simple molecules that populate most synthetic compound libraries, and their structural features tend to be more drug-like than randomly synthesised compounds. (Caithness Biotechnologies)
Further, on a practical level, there are fewer compounds in a natural product library vs a synthetic product library, which facilitates efficacy by smaller and/or less well-funded research groups.
All teas shown here are available at TeaHaus.
See previous post: Amid the COVID-19 Pandemic, a Look at Tea and Stress
–Bahramsoltani, Roodabeh et al., “The preventive and therapeutic potential of natural polyphenols on influenza,” Expert Review of Anti-infective Therapy 14(1). 2016.
–Bayraktar, Oguz, et al., “Nanocarriers for plant-derived natural compounds,” Nanostructures for Antimicrobial Therapy, ed. by A. Ficai and A. Grumezescu, Elsevier, 2017.
–Carneiro, Bruno M., et al., “The green tea molecule EGCG inhibits Zika virus entry,” Virology 496:215–18. September 2016.
–Caithness Biotechnologies, accessed March 18, 2020.
–Chen, Chia-Nan, et al., “Inhibition of SARS-CoV 3C-like protease activity by theaflavin-3,3′-digallate (TF3),” Evidence-Based Complementary and Alternative Medicine, vol. 2. 2005.