Assessing the Safety of Vitamin A Delivered Through Large-Scale Intervention Programs: Workshop Report on Setting the Research Agenda

Background: Vitamin A (VA) deficiency (VAD) is still a concern in many parts of the world, and multiple intervention strategies are being implemented to reduce the prevalence of VAD and associated morbidity and mortality. Because some individuals within a population may be exposed to multiple VA interventions, concerns have been raised about the possible risk of hypervitaminosis A. Objectives: A consultative meeting was held in Vienna, Austria, in March 2014 to (1) review current knowledge concerning the safety and effectiveness of large-scale programs to control VAD, (2) develop a related research agenda, and (3) review current available methods to assess VA status and risk of hypervitaminosis A. Methods: Multiple countries were represented and shared their experiences using a variety of assessment methods, including retinol isotope dilution (RID) techniques. Discussion included next steps to refine assessment methodology, investigate RID limitations under different conditions, and review programmatic approaches to ensure VA adequacy and avoid excessive intakes. Results: Fortification programs have resulted in adequate VA status in Guatemala, Zambia, and parts of Cameroon. Dietary patterns in several countries revealed that some people may consume excessive preformed VA from fortified foods. Conclusion: Additional studies are needed to compare biomarkers of tissue damage to RID methods during hypervitaminosis A and to determine what other biomarkers can be used to assess excessive preformed VA intake.