“So we suspected that patterns of smell loss would differ between the two groups,” he said.
Philpott and his colleagues studied smell and taste function in 10 Covid-19 patients, 10 acute cold patients and 10 healthy people who served as a control group.
The researchers not only found that the smell and taste function of Covid-19 patients was significantly worse than in both the cold patients and the healthy individuals — but also the ability to detect sweet and bitter tastes was particularly impaired in Covid-19 patients.
“It is particularly interesting that Covid-19 seems to particularly affect sweet and bitter taste receptors, because these are known to play an important role in innate immunity,” Philpott said in the release.
Philpott called for additional research to explore the relationship between the virus and these taste receptors.
“It was this loss of true taste which seemed to be present in the Covid-19 patients compared to those with a cold,” he said in the release.
The researchers believe that loss of taste in Covid-19 patients isn’t just more severe, but is caused by a different mechanism in the olfactory system, which is responsible for the body’s sense of smell. The researchers say their findings indicate that Covid-19 patients are experiencing a direct loss of the ability to taste, rather than an indirect loss of taste because the sense of smell is impaired.
Covid-19 can produce increased inflammation throughout the body. The researchers suggest that this inflammation can damage taste receptors. They say it is also possible that Covid-19 can affect a part of the brain stem connected to the sense of taste.
Both the Covid-19 and cold patient groups in the study reported improvement in their sense of taste and smell over time, although only 30% of Covid-19 patients reported complete recovery.
The researchers say it is likely that a portion of the Covid-19 patients will experience persistent loss of taste after they clear the virus.
The research had some limitations, including the small study size. More research is needed to determine whether similar findings would emerge among a larger group of Covid-19 and cold patients.
Yet overall, Philpott and colleagues say smell and taste tests can discriminate between Covid-19 and cold patients, which means these tests could potentially be an additional screening tool for those with the novel coronavirus.
That symptom appears to be more prevalent in mild or moderate cases of Covid-19, and tends to appear at the beginning of the illness. It may even be one of the first signs that you are sick.
CNN’s Sandee LaMotte contributed to this report.