The association between salivary zinc levels and dysgeusia in COVID-19 patients

Abstract

Objective: Zinc insufficiency has been proposed to play a role in taste and smell impairment in Coronavirus disease 2019 (COVID-19) patients. Therefore, this study aimed at comparing salivary zinc levels in COVID-19 patients with and without dysgeusia.

Patients and methods: A total of 127 participants were recruited for this study. The patients were divided into three groups based on their COVID-19 test results and taste impairment. Groups I and II were COVID-19 positive with and without taste loss, respectively. Group III included the negative control participants. Salivary zinc levels were measured at baseline in all groups and three months after baseline in groups I and II. Wilcoxon signed-rank test was used to compare the zinc levels between baseline and three months after baseline within each group. Mann-Whitney U test was used to compare zinc levels between groups with different degrees of taste loss.

Results: Salivary zinc levels were significantly lower in the COVID-19 positive group with taste loss compared to levels in the group without taste loss or the negative controls (p<0.005). Three months after baseline, salivary zinc levels were significantly elevated in both COVID-19 positive groups (p<0.001).

Conclusions: COVID-19 patients with dysgeusia had significantly lower levels of salivary zinc than positive and negative controls. Zinc levels were elevated after recovery, which may indicate that salivary zinc is directly associated with taste abnormalities and COVID-19 outcomes. This study showed that taste impairment is associated with lower salivary zinc levels in COVID-19 patients.