Impact of Nutritional Status on COVID-19-Induced Olfactory Dysfunction

Objective: Although olfactory dysfunction is one of the most common presenting signs of COVID-19 infection, little is known about which populations are most susceptible. The aim of this study is to evaluate the risk of COVID-19-induced chemosensory dysfunction in malnourished individuals. Methods: The N3C database was queried for adults having positive COVID-19 test result, diagnosis of chemosensory dysfunction within 2 weeks of positive test date, and overnutrition or undernutrition (i.e., deficiency or excess of micro- and macronutrients) related diagnoses prior to COVID-19 infection. Individuals previously diagnosed with chemosensory dysfunction were excluded. COVID-19-positive adults without olfactory dysfunction were similarly analyzed. Statistical analysis was performed using odds ratio calculations (95% confidence interval [CI]). Results: Of 3,971,536 patients with COVID-19, 73,211 adults were identified with a diagnosis of undernutrition and 428,747 adults were identified with a diagnosis of overnutrition prior to infection. Of those with undernutrition, 264 (0.36%) individuals were identified with a diagnosis of olfactory dysfunction within 2 weeks of infection. Of those with overnutrition, 2851 (0.66%) individuals were identified with a diagnosis of olfactory dysfunction within 2 weeks of infection. The calculated odds ratio for undernutrition and olfactory dysfunction was 0.731 (p < 0.0001, 95% CI [0.0647, 0.0825]). The calculated odds ratio for overnutrition and olfactory dysfunction was 1.419 (p < 0.0001, 95% CI [1.3359, 1.5081]). Conclusion: Overnutrition may increase the risk of COVID-19-related olfactory dysfunction, while undernutrition may slightly protect. While reasons are unclear, baseline differences in metabolic, inflammatory, and structural biochemistry deserve closer inspection. Level of Evidence: 3