Zinc Absorption From Zinc Biofortified Rice

It is well documented that zinc supplementation to low-income population results in the reduced incidence of childhood diarrhoea and pneumonia, and improves growth of stunted children. Implementation of large scale programmes are needed for prevention of zinc deficiency in areas where it is common. In Bangladesh, the risk of zinc deficiency is considered to be high and children could benefit greatly by improving their zinc intakes on a daily basis. Zinc supplementation at a national scale would be a formidable task and even if implemented might not be sustainable in the long range. There thus is a need to find an alternative. It might be sustainable to improve intake of zinc through fortified staples, e.g. rice with increased amounts of zinc; in fact such biofortified rice has been developed through conventional breeding, which is designed to contain an amount of zinc that could meet at least 40% of the daily requirement.

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.