The spread of severe acute respiratory syndrome coronavirus [SARS-CoV-2] has consequently led to the global COVID-19 pandemic. Many patients, whether hospitalized or not, have reported a variety of complications that persist after recovery. The admission for COVID-19 has been associated with anosmia and hyposmia, the inability or decreased ability to smell. Deficiencies in the ability to smell tend to recover within weeks. However, a significant number of cases have been reported in which smell distortions last for several months. Experimental research has identified inflammation as a factor disrupting olfactory neurons. Precisely, local inflammation through cytokine release in sustentacular and horizontal basal cells interferes with the function of olfactory neurons. Further studies have reported that these local inflammatory events are not responsive to common corticoid treatments. Therefore, in order to mediate the recovery of olfaction in COVID-19 patients after viral recovery, this study evaluates vitamin C, vitamin D, vitamin E, and omega-3 polyunsaturated fatty acids to develop a prospective dietary approach with anti-inflammatory properties to reduce the local inflammation of sustentacular and horizontal basal cells.

Neurogenesis is vital in the preservation of cognition. Previous studies have reported antioxidant vitamins as a key regulatory factor in neurogenesis. However, current research investigating their role is inconclusive due to the limited number of studies that have been conducted and conflicting results. This review evaluates the scientific evidence behind the potential roles of antioxidant vitamins in neurogenesis. Observations concerned with the mechanistic and functional aspects of how antioxidant vitamins modulate neurogenesis are both assessed. Vitamin A is evidently involved in cell cycle regulation and cell proliferation; vitamin C reportedly promotes neural differentiation and maturation while inhibiting neurite outgrowth; vitamin E is identified to inhibit cell proliferation while improving cell viability. Varying antioxidant vitamin concentrations have been implicated in facilitating cognition in terms of attention, memory, language, and executive function. Moreover, this review suggests a threshold antioxidant vitamin concentration that should be maintained to promote optimal levels of adult neurogenesis.