Vitamin A in resistance to and recovery from infection: relevance to SARS-CoV2

Abstract

SARS-CoV2 infects respiratory epithelial cells via its cellular receptor angiotensin-converting enzyme 2 (ACE2), causing a viral pneumonia with pronounced inflammation resulting in significant damage to the lungs and other organ systems, including the kidneys, though symptoms and disease severity are quite variable depending on the intensity of exposure and presence of underlying conditions that may affect the immune response. The resulting disease, COVID-19, can cause multi-organ system dysfunction in patients requiring hospitalization and intensive care treatment. Serious infections like COVID-19 often negatively affect nutritional status and the resulting nutritional deficiencies may increase disease severity and impair recovery. One example is the viral infection measles, where associated vitamin A (VA) deficiency increases disease severity and appropriately timed supplementation during recovery reduces mortality and hastens recovery. VA may play a similar role in COVID-19. First, VA is important in maintaining innate and adaptive immunity to promote clearance of a primary infection as well as minimize risks from secondary infections. Second, VA plays a unique role in the respiratory tract, minimizing damaging inflammation, supporting repair of respiratory epithelium and preventing fibrosis. Third, VA deficiency may develop during COVID-19 due to specific effects on lung and liver stores caused by inflammation and impaired kidney function, suggesting that supplements may be needed to restore adequate status. Fourth, VA supplementation may counteract adverse effects of SARS-CoV2 on the angiotensin system as well as minimizing adverse effects of some COVID-19 therapies. Evaluating interactions of SARS-COV2 infection with VA metabolism may thus provide improved COVID-19 therapy.

A novel hypothesis for COVID-19 pathogenesis: Retinol depletion and retinoid signaling disorder

“…COVID-19 patients display multiple signs and symptoms that typically resemble those of VAD that develop due to retinol depletion and impaired retinoid signaling. For example, some laboratory and radiological imaging findings, clinical observations, and symptoms of COVID-19 resemble those of VAD [132] , [133] , [134] , [142] , [143] . Many of these signs and symptoms, such as changes in the immune system, central nervous system, and eyes, and especially the smell and taste disturbance, are also very common in VAD [142] , [143] , [144] .…”

“…For example, some laboratory and radiological imaging findings, clinical observations, and symptoms of COVID-19 resemble those of VAD [132] , [133] , [134] , [142] , [143] . Many of these signs and symptoms, such as changes in the immune system, central nervous system, and eyes, and especially the smell and taste disturbance, are also very common in VAD [142] , [143] , [144] . Likewise, the changes observed in immune system in COVID-19 infections are drastically similar to those of immune system suppression seen in VAD [123] , [126] , [145] , [146] .…”

“…VitA deficiency (VAD)is associated with inflammation and dietary intake of VitA is required for the maintenance of the anti-inflammatory state of tissue-resident intestinal macrophages [68] , [188] . VAD has been shown to increase infectious disease burden and decrease host resistance against viral infections [27] , [61] , [75] , [142] , [189] and impairs B and T cell responses to viral vaccines [28] . In addition, VitA levels decrease during viral infections indicating the importance of active usage of VitA in the anti-viral immunity [142] , [190] .…”

“…VAD has been shown to increase infectious disease burden and decrease host resistance against viral infections [27] , [61] , [75] , [142] , [189] and impairs B and T cell responses to viral vaccines [28] . In addition, VitA levels decrease during viral infections indicating the importance of active usage of VitA in the anti-viral immunity [142] , [190] . The immune system's response to viral and parasitic infections is compromised in VAD, and if not restored, the duration and severity of this deficiency-related conditions worsen [191] , [192] .…”

Fat-Soluble Vitamins and the Current Global Pandemic of COVID-19: Evidence-Based Efficacy from Literature Review

“…77,[80][81][82] Moreover, it has been reported that vitamin A can minimize COVID-19-induced adverse effects on the angiotensin system and minimize medication-related adverse effects. 83 On top of these novel beneficial effects, vitamin A, is well known for the positive role in promoting innate and adaptive immunity. 2 By this means, vitamin A prevents or diminishes primary and secondary infections.…”