Mega doses of retinol: A possible immunomodulation in Covid-19 illness in resource-limited settings
et al., Reviews in Medical Virology, doi:10.1002/rmv.2204 (Review)
, Mega doses of retinol: A possible immunomodulation in Covid-19 illness in resource-limited settings, Reviews in Medical Virology, doi:10.1002/rmv.2204 (Review)
Review of the potential benefits of vitamin A for COVID-19, including the effect of vitamin A on ACE2 expression in the respiratory tract, potentially improving the generation of protective immune responses to vaccines, and dosage and safety analysis.
Midha et al., 31 Dec 2020, peer-reviewed, 4 authors.
Mega doses of retinol: A possible immunomodulation in Covid‐19 illness in resource‐limited settings
Reviews in Medical Virology, doi:10.1002/rmv.2204
Of all the nutrients, vitamin A has been the most extensively evaluated for its impact on immunity. There are three main forms of vitamin A, retinol, retinal and retinoic acid (RA) with the latter being most biologically active and all-trans-RA (ATRA) its main derivative. Vitamin A is a key regulator of the functions of various innate and adaptive immune cells and promotes immune-homeostasis. Importantly, it augments the interferon-based innate immune response to RNA viruses decreasing RNA virus replication. Several clinical trials report decreased mortality in measles and Ebola with vitamin A supplementation. During the Covid-19 pandemic interventions such as convalescent plasma, antivirals, monoclonal antibodies and immunomodulator drugs have been tried but most of them are difficult to implement in resource-limited settings. The current review explores the possibility of mega dose vitamin A as an affordable adjunct therapy for Covid-19 illness with minimal reversible side effects. Insight is provided into the effect of vitamin A on ACE-2 expression in the respiratory tract and its association with the prognosis of Covid-19 patients. Vitamin A supplementation may aid the generation of protective immune response to Covid-19 vaccines. An overview of the dosage and safety profile of vitamin A is presented along with recommended doses for prophylactic/therapeutic use in randomised controlled trials in Covid-19 patients.
CONFLICT OF INTEREST All the authors declare that there is no conflict of interest.
AUTHOR CONTRIBUTIONS Ish K. Midha conceived the idea for the review and prepared the draft. Nilesh Kumar and Amit Kumar contributed to the draft with respect to role of vitamin A in recognition of RNA viruses and impact of Vitamin A on ACE-2 and prognosis of Covid-19 patients respectively. Taruna Madan contributed to the draft for immunemodulatory role of vitamin A and preparation of the figures.
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