Absorption of zinc from mixed diets containing conventional Bangladeshi rice, zinc-biofortified Bangladeshi rice, or conventional Bangladeshi rice with added zinc among young children from a peri-urban community in Bangladesh

Background Previous studies showed total absorbed zinc (TAZ) was comparable in diets containing a higher zinc rice variety or conventional rice variety (Lo-Zn CR). This study compared TAZ in a polished zinc-biofortified rice (Hi-Zn BfR) compared with Lo-Zn CR.

Objective To measure the amount of TAZ by young Bangladeshi children from Hi-Zn BfR, Lo-Zn CR, or CR plus sufficient exogenous zinc fortificant (Lo-Zn CR+Zn) matching the zinc content of Hi-Zn BfR.

Methods A total of 47 children 36–59-mo-old were enrolled in a crossover study. On the day 1, children received a Lo-Zn CR diet. On days 2 and 4, group A (n = 23) received 150 g of Lo-Zn CR and group B (n = 24) received 150g of Lo-Zn CR+Zn as part of a mixed diet. On days 3 and 5, both groups received 150 g of Hi-Zn BfR. Fractional zinc absorption (FZA) was measured in all diet periods using a triple-isotope tracer (oral 67-Zn and 70-Zn; intravenous 68-Zn) ratio technique; TAZ was calculated as product of zinc intake [total dietary zinc (TDZ)] and FZA.

Results TDZ was 4.88, 6.14, and 6.70 mg/d when fed Lo-Zn CR-, Lo-Zn CR+Zn-, and Hi-Zn BfR-containing diets, respectively. Mean FZA: 0.23 ± 0.041, 0.169 ± 0.035, and 0.212 ± 0.048 for respective diets (Lo-Zn CR compared with Hi-Zn BfR: P = 0.26; Lo-Zn CR+Zn compared with Hi-Zn BfR: P < 0.001; and Lo-Zn CR compared with Lo-Zn CR+Zn: P < 0.001). Mean TAZ from respective diets were 1.13 ± 0.23, 1.04 ± 0.20, and 1.40 ± 0.33mg/d. TAZ was not significantly different between Lo-Zn CR and Lo-Zn CR+Zn diets (P = 0.52) but was significantly more in Hi-Zn BfR when compared with other 2 diets (P < 0.001 for both).

Conclusions A single-day ration (150 g total) in 3 equally divided servings of Hi-Zn BfR could satisfy 47% of the recommended daily requirement of zinc (3 mg/d) for children 1–3-y old and 28% for children 4–8-y old (5 mg/d) compared with 37% and 23% from Lo-Zn CR for the same age groups, respectively. Hi-Zn BfR is a meaningful component of preventive option for childhood zinc deficiency where rice is staple.