To assess the potentials for biofortified rice in providing a good, bioavailable source of additional zinc, the investigators propose to measure zinc absorption from rice-based meals among Bangladeshi preschool children. Specifically, the investigators will measure the amount of zinc absorbed from zinc-biofortified rice (Diet-ZBfR, 24 mg Zn/kg), compared to that absorbed from a conventional Bangladeshi rice (Diet-CR, 16 mg Zn/kg) (control). The investigators will also compare the zinc absorption from biofortified rice with that from zinc-fortified conventional rice (Diet-CR+Z). The study will be a cross-over, randomized, controlled clinical study. In total, 42 children aged 36-59 months of either sex will be recruited from a peri-urban community in Dhaka, and they will be individually randomized, in equal numbers, to one of the two comparison groups, A and B. The group A children will receive zinc biofortified rice-based diet (Diet-ZBfR) and conventional rice-based diet (Diet-CR) using a randomized, cross-over design. Similarly, the group B children will receive zinc biofortified rice-based diet (Diet-ZBfR) and a zinc fortified rice based diet (Diet-CR+Z), also using randomized, cross-over design. The investigators will use zinc stable isotope tracer techniques to measure the fractional absorption of zinc, in which tracer : tracee ratios will be measured in spot urine samples following administration of an intravenously administered tracer (68Zn) and one of two oral tracers (70Zn, 67Zn) provided with test meals over a two-day period. If zinc from biofortified rice is found to be adequately bioavailable, it will be tested in a randomized, controlled, efficacy trial among rural Bangladeshi children.