title: Can lack of improvement in vitamin A status indicators be explained by little or no overall change in vitamin A status of humans?
abstract: Changes in vitamin A status using conventional indicators, i.e., serum and breast milk retinol concentrations and the modified relative dose response test, following a vitamin A intervention have not always been shown. A simplified model to predict calculated changes in vitamin A status after intervention is described. The model shows that changes in indicator values cannot be expected if the change in vitamin A status is only marginal. A critical review of several papers using vitamin A status assessment indicators was undertaken. Assumptions that included current knowledge concerning vitamin A absorption and metabolism were made and applied to the data. Based on current recommended daily allowances for women and children, one cannot necessarily expect a change in indicators if an overall change in vitamin A status was not achieved. Thus, when designing vitamin A intervention studies, the following parameters should be considered if applicable to the population to be enrolled in the study: average body weight, estimated liver weight, amount of vitamin A administered, estimated loss in breast milk and study duration.
authors.affiliation: Department of Nutritional Sciences, University of Wisconsin at Madison, Madison, WI 53706, USA. sherry@nutrisci.wisc.edu
authors.forename: S A
authors.initials: SA
authors.lastname: Tanumihardjo
mesh_terms: D005260:Female; D006801:Humans; D008099:Liver / Q000737:chemistry; D008895:Milk, Human / Q000737:chemistry; D008954:Models, Biological; D015596:Nutrition Assessment; D009752:Nutritional Status; D014801:Vitamin A / Q000008:administration & dosage / Q000032:analysis / Q000097:blood
chemical_list: D014801:Vitamin A