Choice of study population
The study was carried out in a population with a marginal vitamin A status to enable detection of changes in vitamin A status.
By selecting children with anemia, we managed to select a population with an average serum retinol concentration of 0.71
mmol/L. This is comparable with concentrations found in a national survey in Indonesia of children aged < 5 y (19). However, the serum retinol concentration of schoolchildren in general is expected to be slightly higher than that of our study population because we only studied anemic children.