You probably remember hearing about people who lost their sense of taste during the pandemic. For most, it came back within weeks. For others, favorite meals have tasted like cardboard ever since.
Now a team at the University of Colorado Anschutz and two Swedish universities thinks it has pinned down why.
In a study published in Chemical Senses, the researchers report that taste cells in these patients are low on a specific protein that normally boosts the signal from tongue to brain.
The protein is called PLCβ2. It sits inside the taste cells that detect sweet, bitter, and savory (also called umami) flavors. When it works, it turns a small chemical nudge into a clear message the brain can read. When it is in short supply, that message fades.
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How the researchers tested it
The team examined 28 people who had kept having taste problems for more than a year after a COVID-19 infection. None of them had been sick enough to go to the hospital. Twenty of them agreed to let the researchers take tiny tissue samples from the tongue.
Taste testing on the group showed a clear pattern. Sweet, bitter, and savory were the flavors that kept coming up wrong. Salty and sour were mostly left alone. Eleven of the 28 could not detect at least one of the taste qualities at all.
The tissue samples pointed in the same direction. Levels of the messenger RNA that cells use to build PLCβ2 were lower than normal, and some taste buds looked disorganized under the microscope.
"PLCβ2 acts like a molecular amplifier inside taste cells," said Thomas Finger, professor of cell and developmental biology at the University of Colorado Anschutz. His institution's statement was carried by EurekAlert.
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"It strengthens the signal before it's transmitted to the brain. When levels are reduced, the taste signal weakens."
Why salty and sour are spared
Salt and acid are detected through different cells that do not need PLCβ2 to pass their signal along. That is why many patients who struggle with their morning coffee or a bowl of pasta can still clearly taste a pinch of salt or a squeeze of lemon.
The study is small and does not prove that the protein shortage is the only cause of long-term taste problems. The researchers also saw taste buds that looked unusual in shape, so more than one process may be at work at once.
Still, it is one of the first findings to tie a specific molecule to the symptom.
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How many people this may affect
Taste loss after COVID is not rare.
A cross-national survey of 2,745 adults was published in July 2026 in the International Forum of Allergy & Rhinology. It found that 22.9 percent of US participants and 17.3 percent of UK participants reported ongoing taste loss in the post-pandemic years.
For readers who are still waiting for sweet, bitter, or umami to come back, there is no approved treatment aimed at PLCβ2 yet.
The authors suggest it is a promising target for future therapies, and they recommend that patients with persistent taste changes see an ear, nose, and throat doctor to rule out other causes.
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This article is made and published by Aksel Kryhlmand, who may have used AI in the preparation.