A small study published in March and drawing new attention this month found molecular and structural changes in taste cells of people whose taste problems lasted more than a year.

Taste bud samples from people whose sense of taste stayed impaired for more than a year after COVID-19 showed reduced activity of a protein that amplifies sweet, bitter, and savory signals, according to a study in the journal Chemical Senses. The researchers call it a possible explanation for why some foods can stay flavorless long after infection.

The study, led by researchers at the University of Colorado Anschutz with two Swedish universities, was published March 2 and is drawing fresh attention after ScienceDaily featured it this month. It involved 28 people, none of whom had been hospitalized for COVID-19, who reported taste problems lasting more than a year. The work was organized by Göran Hellekant of the University of Wisconsin and the Swedish University of Agricultural Sciences.

For people still living with dull food years after infection, the finding matters because it points to a measurable change in taste cells rather than a problem that is all in their heads, though — importantly — it does not yet lead to a treatment.

What Researchers Saw Inside the Taste Buds

Of the 28 participants, eight had clearly abnormal scores on taste tests, and 11 had trouble detecting specific tastes, mainly sweet, bitter and umami, the savory taste of broth and aged cheese. Salty and sour tastes were largely spared.

The team took tiny taste bud samples from 20 participants. They found reduced messenger RNA for PLCβ2, a protein that boosts the signal inside taste cells that detect sweet, bitter and umami. "PLCβ2 acts like a molecular amplifier inside taste cells," said corresponding author Thomas Finger, a professor of cell and developmental biology at CU Anschutz, according to the university.

Because sweet, bitter and umami cells all rely on PLCβ2 in their signaling chain, a shortfall in that one protein could dull three tastes at once. Cells that detect salty and sour use different signaling pathways that do not depend on PLCβ2, which may explain why those tastes held up. The authors described their results as "measurable evidence of long-term taste disruption in some post-COVID patients." The tissue samples also varied. "Some subjects had normal-looking taste buds, while others showed structural disorganization," Finger said, suggesting both molecular and structural changes may play a role.

Taste Cells Renew, So Why Doesn't Taste Bounce Back?

Taste bud cells normally turn over every two to four weeks, so damage to individual cells would usually be repaired quickly. The researchers found evidence that the signaling disruption may persist much longer in some people, well beyond many rounds of cell renewal.

That raises a possibility the study did not answer: whatever changed may affect how new taste cells develop, not just the cells present during infection. The team said further work is needed to learn whether the dysfunction can fully reverse and whether therapies could restore normal taste signaling, according to the Swedish University of Agricultural Sciences, one of the partner institutions.

Evidence Check: Small Study, Competing Explanations

This was a small study, with 28 people tested and 20 biopsied, and the published summaries do not describe a comparison group of people without long COVID. That makes it hard to know how unusual the PLCβ2 levels are, and the findings may apply only to a subgroup of patients.

Other research points in a different direction. A 2024 national study in JAMA Network Open found that taste problems had largely cleared a year after COVID-19 while smell problems lingered, and suggested long-term taste complaints may reflect damage to smell-sensing tissue rather than taste buds, according to a summary by the American Society for Clinical Pathology. Much of what people call flavor comes from smell. In that study, smell problems affected 30.3% of people with prior COVID-19 compared with 21% of those without a known infection.

The two findings may describe different groups of patients. The new study offers what its authors call the first direct biological evidence of taste cell changes, which other researchers will need to confirm.

Living with Muted Flavors and Getting Checked

The scale of the problem is meaningful. A 2022 analysis in the BMJ estimated that about 4.4% of COVID-19 patients may develop long-lasting taste problems, roughly 12 million people worldwide at the time, although 79% had recovered taste within 30 days, according to Singapore General Hospital, which led the work.

People who have lost taste for months should talk with a primary care doctor or an ear, nose and throat specialist, who can test taste and smell separately and rule out other causes such as medications, dental problems or nerve conditions. Keeping notes on which tastes seem weaker, and whether smell has changed too, can help that visit. Separating taste from smell matters, because the causes and the specialists involved can differ.

There is no approved treatment based on this finding, so be cautious about supplements or products marketed as taste cures. Seek prompt care if taste loss comes with sudden weakness, facial drooping, or trouble swallowing, which can signal other serious conditions.

What happens next is larger studies with comparison groups and tests of whether taste signaling can be restored. The bottom line is that low levels of a signal-boosting protein offer a possible, not proven, explanation for lasting taste loss after COVID-19, and people affected should seek a medical evaluation rather than wait.

What Readers Want to Know

What did the study find?

Taste bud samples from some long COVID patients had reduced messenger RNA for PLCβ2, a protein that amplifies sweet, bitter, and umami signals.

Which tastes were most affected?

Sweet, bitter, and umami. Salty and sour were largely preserved because those cells use different signaling pathways.

Is this a new study?

It was published in Chemical Senses on March 2, 2026, and drew renewed attention this month.

Does this prove why taste loss lasts?

No. It is a possible explanation from a small study, and some research suggests lasting flavor loss is mostly tied to smell.

Is there a treatment?

Not yet. Researchers say more work is needed to see if taste signaling can be restored.

Who should I see about lasting taste loss?

A primary care doctor or an ear, nose, and throat specialist who can test taste and smell and check for other causes.