The other containers were frozen at
220 8C for 1 mo before being transferred, packed in dry ice, to
Wageningen. The samples were then stored for 3–6 mo at 280 8C
until analyzed for retinol, carotenoids, ferritin, and transferrin
receptor. Retinol and carotenoids were analyzed (5, 7) at the
Division of Human Nutrition and Epidemiology, Wageningen
Agricultural University.