Objective: The Biomarkers of Nutrition for Development (BOND) project was designed to provide evidence-based information to anyone interested in the role of nutrition in health. The BOND program provides state-of-the-art information with regard to selection, use, and interpretation of biomarkers of nutrient exposure, status, function, and effect for a variety of nutrients.
Methods: An expert panel was recruited for vitamin A to evaluate the literature and to write a comprehensive report on the current state of the art research with regard to specific vitamin A biology and available biomarkers for assessing nutritional status at the individual and population level.
Results: Although vitamin A was discovered more than 100 years ago, vitamin A status assessment is not trivial. Serum retinol concentrations are under homeostatic control due in part to its use in the body for growth and cellular differentiation and because of its toxic properties at high concentrations. Furthermore, serum retinol concentrations are depressed during infection and inflammation because retinol-binding protein is a negative acute phase reactant. This report summarized a variety of biomarkers for vitamin A and reviewed literature to support liver concentrations associated with biomarker utility.
Conclusions: This review described the clinical, functional, and biochemical biomarkers of vitamin A status and how they relate to liver vitamin A concentrations, which are usually considered the gold standard for vitamin A status. In regard to biomarkers, future research questions and lapses in our current understanding as well as limitations of the methods are described.