Clinical and Nutritional Implications of Vitamin A-An Updated Review for Dietitian and Nutritionists.

Abstract

Background: Vitamin A encompasses retinol, retinyl esters, and provitamin A carotenoids that underpin vision, epithelial integrity, immune modulation, and gene regulation through retinal and retinoic acid. 

Aim: To synthesize contemporary evidence on clinical indications, mechanisms, pharmacokinetics, dosing, populationspecific considerations, adverse effects, and monitoring strategies for vitamin A to inform dietitians, nutritionists, and clinicians. 

Methods: Narrative review of established guidance and summarized evidence as presented in the manuscript, including FDAapproved and offlabel uses, WHO grading of deficiency manifestations, pediatric and maternal considerations, toxicity profiles, drug interactions, and monitoring parameters. 

Results: Vitamin A deficiency remains a global publichealth challenge, with supplementation reducing childhood morbidity and mortality, and serving key roles in xerophthalmia, severe malnutrition, measles, and select neonatal indications. Parenteral therapy is reserved for malabsorption or intolerance to oral dosing. Mechanistically, vitamin A supports phototransduction and RARmediated transcription, while hepatic storage and biliary elimination govern its pharmacokinetics. Riskbenefit varies in pregnancy and hepatic/renal impairment. Toxicity spans acute to chronic syndromes, including hepatotoxicity and teratogenicity; interactions with agents such as orlistat and oral contraceptives warrant caution. Monitoring relies primarily on serum retinol (as a proxy for hepatic stores) and targeted labs when derivatives like isotretinoin are used. 

Conclusion: Judicious, evidencebased vitamin A use—prioritizing dietary sources, targeted supplementation in highrisk settings, age and conditionappropriate dosing, and vigilant monitoring—maximizes benefit while minimizing toxicity. Interprofessional coordination is essential to optimize outcomes.