Synergistic interactions of vitamin A, vitamin D, and iron deficiency on health

Abstract Objective This review aims to explore and synthesize existing evidence on the combined impact of vitamin A, D, and iron deficiencies on health outcomes, with a particular focus on young adults. Design A scoping review methodology was employed to comprehensively map the existing literature. Settings A systematic search was conducted in three electronic databases: PubMed, Web of Science, and Scopus, to identify studies examining the individual and combined effects of vitamin A, D, and iron deficiencies. Studies relevant to the research question were screened, and eligible articles were included for data extraction and thematic synthesis. Participants The review focused on young adults aged 18–35 years. This population group is particularly vulnerable to emerging nutritional deficiencies due to dietary transitions and lifestyle factors. Results The evidence indicates a strong physiological and functional correlation between vitamin A, D, and iron. These micronutrients are involved in various metabolic pathways, including bone metabolism and remodelling, erythropoiesis, and immune functions. Deficiencies in one nutrient may impair the function or regulation of the others. For instance, vitamin D influences hepcidin expression and iron mobilization, while vitamin A supports erythropoietin production and iron absorption. Conclusion Vitamins A, D, and iron function synergistically in balancing metabolic and physiological pathways. Their combined deficiency can exacerbate adverse health outcomes, particularly in young adults. This review highlights the need for integrated nutritional approaches and public health policies that account for the interplay among multiple micronutrients.