Structural, functional, nutritional and clinical aspects of vitamin A: a review

The importance of vitamin A to human health is neither a new nor emerging topic; however, information regarding its primary food sources, chemical structure, physiological role, pharmacokinetics, dosage, and relationship with various pathologies is not always concise and hence difficult to understand. Therefore, this review aims to summarise the available information on the role of vitamin A in health and disease in the context of advances in drug discovery and trials. This review includes research articles published between 1974 and 2022 that were identified using multiple search engines such as PubMed, Google Scholar, and ScienceDirect. Select keywords were used to maximize the retrieval of relevant results. The criteria included original research and review articles on the topic. The selection of information sources was based on the publication date with a preference for papers published between 2012 and 2022. After excluding conference proceedings, redundant articles, non-English publications, and website publications from food and medical institutions, 106 articles were included. Vitamin A is a versatile vitamin that is involved in many physiological systems. Previous studies have discovered novel associations between vitamin D and various diseases and potential new indications for drug formulations. Further studies are necessary to assess the efficacy and safety of vitamin A interventions, especially that of retinoids, in the treatment and prevention of several pathologies, some of which are yet to be examined. These future studies could provide better evidence of the clinical significance of retinoids.