A medical expert is convinced tannin can help in the fight against Covid. He spoke exclusively to Wine-Searcher.
By W. Blake Gray | Posted Monday, 08-Feb-2021
It's possible that the tannins in red wine, and tea, could inhibit
Covid-19. A prominent cancer researcher in Taiwan is investigating the
theory right now.
Dr. Mien-Chie Hung is president of China Medical University in
Taiwan. He spent 40 years in the US and for many years was chair of the
department of molecular and cellular oncology at University of Texas MD
Anderson Cancer Center in Houston before moving home to Taiwan in 2019.
His theory is based on Taiwanese research from 2003 into SARS, which
like Covid-19 is caused by a coronavirus. SARS appeared in China in 2002
and killed 774 people in 11 countries before disappearing. There has
not been a case of SARS reported since 2004, although a team at a
different Houston research hospital developed a prototype vaccine in
2016 in the event of a re-emergence. That vaccine has never been tested.
"SARS occurred about a half year, and then totally disappeared," Hung
told Wine-Searcher. "All the research stopped. Nobody wanted to do it
anymore. We thought tannin might have some impact on SARS but the research is incomplete."
Hung said that the Taiwanese lab showed that pure tannic acid can
inhibit two enzymes critical to SARS that are also critical to Covid-19.
First, tannic acid was shown to have the ability to inhibit the main
protease of SARS, which is also the main protease of Covid-19. Proteases
are enzymes that perform necessary biological functions in many
organisms; protease inhibitors are how AIDS drugs work.
Second, tannic acid also inhibits an important enzyme in human cells,
TMP RSS2. This enzyme is on the surface of human cells. When a human is
infected by a coronavirus, the virus recognizes TMP RSS2 on the cell
surface and clips it with its spike protein. Several research projects
are looking into inhibiting TMP RSS2 and one inhibitor of it has already
been approved for clinical use in treating Covid-19.
"Two birds, one stone," Hung said. "The spike protein's entry into
the human cell has two steps. Tannic acid can inhibit both steps."
That's the very good news. Before you start guzzling Malbec, now come the caveats.
First, researchers worked with pure tannic acid. Hung said that
tannic acid is only a part of the tannins of wine and it is unknown if
all tannins will have the same effect on coronaviruses.
"Tannin is rich in the red wine because it is also rich in grapes,"
Hung said. "However, tannic acid is not equivalent to tannin. When we do
research it is very difficult to use a mixture. What we use is pure
compound, and that is tannic acid. That belongs to the tannin family.
Red wine and different fruits, they have tannins in the tannin family.
"Most of the time when people analyze red wine, they analyze tannin.
However, at this moment what we know scientifically is that tannic acid
has the ability to inhibit Covid-19. But will the whole tannin family do
that? We don't know. We have a small group of scientists studying
tannin, the whole group. But while working on that, when you have a
mixture together, it becomes very complicated."
Hung said that normally research like this would proceed at an
academic pace – consider the SARS vaccine finally being developed 12
years after the disease disappeared. He was not satisfied with that,
even though Taiwan has had a relatively easy time with Covid-19 (its
citizens wear masks without complaint) because of the world crisis.
"We need to come out with a strategy that most people would like to
know," Hung said. "I consider this a university social responsibility."
How much is enough?
He was prepared to answer the logical question: How much red wine would you have to drink to get the positive effect?
Before answering, Hung pointed out several assumptions one needs to
make: That all tannins work; that the wine drinker has an average
metabolic rate, because some people can absorb 100 percent of the
tannins in wine into their cells, but others might absorb only 10
percent.
But he did give an estimate: "Based on the human body, based on
research, in order for us to drink enough wine to have tannin
concentration to reach [inhibitory effect], it would have to be about
one liter."
Drinking a liter of wine every day would cause other health problems
and isn't worth it. But it is encouraging – and significant – that the
hypothetical number is not, say, 100 liters.
The reason is this: Covid-19 does not cause symptoms in everyone
infected. This means some people carry it in their systems, perhaps for a
while. Their immune systems succeed in preventing it from causing
illness.
"Those who are Covid-negative, are they really negative?" Hung said.
"Their concentration is so low that under the current detection systems,
they are not detected. When a virus infects a human being, we are
fighting with the virus all the time. If your system is strong enough to
fight the virus, you don't become sick. Since we are fighting with the
virus all the time, if you drink red wine, the concentration [of tannic
acid] might not be high enough to reach the level we use in the lab. But
the low dose might have a mild prevention effect."
I have been trying not to overstate the significance of this
research, but there's no doubt that the following quote is what the wine
industry and wine drinkers want to hear:
"If two people are infected by the same amount of virus, but one
drinks wine and the other one doesn't," Hung said, "The one who drinks
the tannic acid, their protection will be stronger than the other."
Hung does not drink wine himself; ironically he said he does not have
the enzyme to process alcohol (a relatively common complaint among
Asians.) Initially he planned to do the research around tea, for which
Taiwan is well known.
"I drink tea all the time," Hung said. "This one, for wine, I did not
expect to get so much attention. We knew about tannic acid, this
activity, about a half year ago. We think, we better know more about it.
Then we decide, it's not fair to the community. We decide we have to
say what we know. When we first started, we talked about tea."
But he said wine companies contacted him and urged him to research
wine, and he believes it is university social responsibility to do so.
Hung doesn't drink wine, but his sister owns Lichau Hill Vineyards on Sonoma Mountain;
she bought it in 2012 as a weekend getaway and moved there permanently
from San Francisco after the pandemic started. Hung says he misses
visiting his sister, as well as his son in Houston. Before the pandemic
started, he was flying to Houston every month as part of his goal to
bring top cancer biomedical research to Taiwan to help people.
The last thing he said in our conversation was: "Stay safe and drink wine."
