Loss of Sour Taste Is the Striking Feature among Four Basic Taste Qualities in Tunisian COVID-19 Patients

Abstract

Background: Taste disorders (TDs) have been reported to be very common in patients suffering from coronavirus disease 2019 (COVID-19), which is caused by the SARS-CoV-2 virus. In most of the hitherto conducted studies, a gustatory assessment was performed on the basis of surveys or self-reports by patients. The aim of our study was to undertake an objective assessment of four basic taste qualities by conducting tasting sessions that allowed detection thresholds in COVID-19 Tunisian patients and to study their associations with inflammation. Methods: This analytical cross-sectional study was conducted on 89 patients aged between 21 to 70 years who had been diagnosed with COVID-19. We used Burghart taste strips to assess taste perception of the four taste qualities, i.e., sour, bitter, sweet, and salty. Serum levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and C-reactive protein (CRP) were measured. Results: Taste disorders were reported by 40.4% of the patients, while objective assessments revealed that 63.8% of participants were suffering from hypogeusia and/or ageusia. Sour taste was the most altered (70.8%) gustatory quality. Patients with severe COVID-19 had significantly lower sour and bitter taste scores when compared to patients with minor/moderate forms. There was no significant association between serum inflammatory markers and taste disorders. However, the relationship between bitter and sweet taste qualities and IL-1β levels was significant (p = 0.018 and p = 0.041). Conclusions: Our results demonstrate the interest in the objective assessment of taste dysfunctions in COVID-19 patients.

Post-COVID-19 patients suffer from chemosensory, trigeminal, and salivary dysfunctions

“…Ageusia and specific ageusia, which are rare conditions, were found in almost one-third of the patients. In this study, specific ageusia for bitter, salt, sour and sweet taste was found, consistent with other studies 39 , 40 . Findings from the present study revealed that about one-fifth of post-COVID-19 patients had no bitter taste sensation, about one-tenth had no salt or sour taste sensation, and only one patient reported no sensation for sweet taste.…”

“…Findings from the present study revealed that about one-fifth of post-COVID-19 patients had no bitter taste sensation, about one-tenth had no salt or sour taste sensation, and only one patient reported no sensation for sweet taste. While in the present study, bitter taste ageusia was most common, other studies have reported specific ageusia for sour taste as the most prevalent 39 , 40 . Loss of perception of bitter taste may have serious implications as bitter taste warns about ingestion of potentially harmful, toxic, or poisonous chemical substances 57 .…”

“…The most explored chemosensory dysfunction is parosmia, which has been found to be highly prevalent in post-COVID-19 patients 34 – 36 . Other conditions such as loss of smell (hyposmia 37 , anosmia 37 ), loss of taste (hypogeusia 37 , ageusia 38 , specific ageusia 39 , 40 ), other single taste disturbances 41 – 43 , altered taste (dysgeusia 44 ), xerostomia 45 and trigeminal dysfunction 37 , 46 have also been reported in different sets of patients recovering from COVID-19. However, to our best knowledge, only one study has explored these dysfunctions in the same group of post-COVID-19 patients 45 .…”

COVID-19 on Oral Health: A New Bilateral Connection for the Pandemic

“…One well-known sign of COVID-19, reported in about 40% of SARS-CoV-2 positive individuals, is the loss of taste, and, interestingly, a strong positive correlation has been reported between SARS-CoV-2 RNA in the saliva and patients' self-reported "loss of taste" in symptomatic individuals [155,156]. There have been two patients to date who have reported taste abnormalities linked to a high viral load in their saliva and a considerable epithelial (pCK+) cell infection in ACE2-expressing cells [27].…”

The Revived Interest in Ageusia Research during the COVID-19 Pandemic: A Bibliometric Analysis

“…The third plausible mechanism could be through a direct infection and damage to the cranial nerves responsible for taste sensation, such as the facial nerve, the glossopharyngeal nerve, and the vagus nerve [11]. Some studies reported that patients with COVID-19 suffered from sour and salty taste suppression more severely than bitter and sweet tastes, and suggested that the differences were due to the former two taste qualities being transmitted by ion channels whereas the latter were by transduction via G-protein-coupled receptors [12,13]. Regardless of the pathogenesis, ageusia could have serious implications for the well-being of the affected patients, as a recent study showed that COVID-19-related ageusia might increase the risk of depression and suicidal ideation by 30% [14].…”