One of the biggest mysteries of the novel coronavirus is why it affects some people more severely than others. Now, a group of scientists has found that people who experience a greater-than-average intensity of bitter taste — known as "supertasters" — were less likely to become infected with, or become severely ill from, COVID-19.
This enhanced bitter taste is driven by a gene called T2R38; when a person inherits a copy of the gene from both parents, that person becomes a supertaster, according to The Washington Post.
But this gene does more than enhance the taste of bitterness; it has also been linked to having a better innate immune response against pathogens.
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Those who inherit this gene from both parents tend to have more hair-like filaments, called cilia, in their nose and sinuses, and these filaments help to clear pathogens from the body. When activated, two copies of this gene also trigger the body to produce more mucus and nitric oxide to fight pathogens, according to the Post.
Previous research that focused mainly on bacterial infections and inflammation found that the more intensely people experience bitter tastes, the stronger their innate immune responses are, according to the Post.
In a new study, published May 25 in the journal JAMA Network Open, researchers wanted to see how supertasting affected the ability to fight COVID-19.
Dr. Henry Barham, lead author of the new study and an ear, nose and throat doctor at Baton Rouge General Medical Center in Louisiana, became interested in the question after spending hours and hours performing operations that increased his exposure to SARS-CoV-2, the virus that causes COVID-19, according to the Post. Despite wearing protective gear, some of his colleagues got COVID-19 at the hospital, but Barham, a supertaster, did not.
For the study, Barham and his team recruited 1,935 participants, gave them taste strip tests and asked them to rate how intensely bitter the test strip was. Then, the researchers classified people as supertasters, tasters (those who inherit only one copy of the gene from one parent) or nontasters (those who don't inherit any copy of the gene and who either experience lower intensity of bitter tastes or who don't taste them at all).
They found that 508 participants were supertasters, 917 were tasters and 510 were nontasters. During the course of the study period, from the start of July 2020 to the end of September 2020, a total of 266 participants tested positive for COVID-19, and 55 of them required hospitalization.
Nontasters were "significantly more likely" than tasters and supertasters to test positive for SARS-CoV-2, to be hospitalized and to be symptomatic longer. Of the 55 patients with COVID-19 who were admitted to the hospital, 47 (85%) were nontasters. Of the 266 people who tested positive for COVID-19, only 15 (6%) were supertasters.
Overall, the ability to taste bitterness could accurately predict who was going to develop severe COVID-19 about 94.2% of the time, according to the Post.
Still, the study was small, and the researchers only discovered a potential link between this enhanced ability to taste bitterness and the risk of developing severe COVID-19.
"Our largest limitation in this observational study is the potential for confounding factors and the fact that SARS-CoV-2 is a novel virus, thus preventing prior knowledge of the degree of inoculation, symptoms and outcomes in different populations," the authors wrote.
Still, supertasters should get vaccinated against COVID-19, Barham told the Post. "Even supertasters, as they age, have the potential to get sick, especially if exposed to a high viral load," he said. (Barham has a financial interest in the test kit that was used in the study.)
Read more about the supertaster study in The Washington Post.
Originally published on Live Science.