Vitamin D and smell impairment: a systematic literature review

Abstract

Objective: Smell impairment affects 60-80 per cent of individuals aged over 80 years. This review aimed to identify any association between vitamin D deficiency and smell impairment, and determine the efficacy of vitamin D to treat smell impairment.

Methods: A literature search was conducted across four databases between the years 2000 and 2022. The literature screen was performed by two independent reviewers.

Results: Seven articles were included in this review. Four studies examined the association between vitamin D deficiency and smell impairment, with three studies identifying a significant relationship. Three studies investigated the use of vitamin D as treatment for smell impairment, which found complete resolution or significant symptom improvement after vitamin D deficiency was treated.

Conclusion: This review identified limited studies on this topic. As vitamin D supplementation is relatively cost-efficient, further large-scale studies should be carried out to investigate the efficacy of vitamin D for treating anosmia.

Keywords: Coronavirus; Evidence-based medicine; Smell; Systematic review; Vitamin D.