Gustatory and Saliva Secretory Dysfunctions in COVID-19 Patients with Zinc Deficiency.

Hironori Tsuchiya

doi:10.3390/life12030353

Abstract

Given the ever-progressing studies on coronavirus disease 2019 (COVID-19), it is critical to update our knowledge about COVID-19 symptomatology and pathophysiology. In the present narrative review, oral symptoms were overviewed using the latest data and their pathogenesis was hypothetically speculated. PubMed, LitCovid, ProQuest, and Google Scholar were searched for relevant studies from 1 April 2021 with a cutoff date of 31 January 2022. The literature search indicated that gustatory dysfunction and saliva secretory dysfunction are prevalent in COVID-19 patients and both dysfunctions persist after recovery from the disease, suggesting the pathogenic mechanism common to these cooccurring symptoms. COVID-19 patients are characterized by hypozincemia, in which zinc is possibly redistributed from blood to the liver at the expense of zinc in other tissues. If COVID-19 induces intracellular zinc deficiency, the activity of zinc-metalloenzyme carbonic anhydrase localized in taste buds and salivary glands may be influenced to adversely affect gustatory and saliva secretory functions. Zinc-binding metallothioneins and zinc transporters, which cooperatively control cellular zinc homeostasis, are expressed in oral tissues participating in taste and saliva secretion. Their expression dysregulation associated with COVID-19-induced zinc deficiency may have some effect on oral functions. Zinc supplementation is expected to improve oral symptoms in COVID-19 patients.

Highlights

Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)are well known to present with fever, cough, dyspnea, myalgia, fatigue, myocarditis, cardiomyopathy, arrhythmia, cardiac arrest, anorexia, nausea, and diarrhea [1,2]
Gustatory dysfunction and saliva secretory dysfunction in the early phase of COVID19 and after recovery from COVID-19 are firstly overviewed, and COVID-19 patients are characterized by hypozincemia
Gustatory dysfunction and saliva secretory dysfunction frequently cooccur in patients infected with SARS-CoV-2, and both dysfunctions can persist after recovery from COVID19

Summary

Introduction

Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Are well known to present with fever, cough, dyspnea, myalgia, fatigue, myocarditis, cardiomyopathy, arrhythmia, cardiac arrest, anorexia, nausea, and diarrhea [1,2]. In addition to these clinical manifestations, chemosensory disorders such as anosmia and ageusia have been frequently reported by patients with coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2. It is becoming evident that the symptoms specific to oral tissues and functions are closely associated with COVID-19 [6–8]. COVID-19 patients may develop other oral symptoms such as saliva secretory dysfunction, which results in dry mouth, xerostomia (subjective complaint of oral dryness), and hyposalivation (objective reduction of salivary flow rates) [7,10,11]

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Discussion

Conclusion