Zinc-Biofortified Rice Improves Growth in Zinc-Deficient Rats

Biofortification of staple food crops with zinc (Zn) is considered a sustainable strategy to prevent deficiency, but evidence on their health impact is awaited. The weaning Wistar/Kyoto male rats were fed on a Zn-deficient diet (ZDD, < 0.1 ppm) for 4 weeks followed by repletion (pair feeding) with control rice diet without (CRD; 5.0 ± 0.23 ppm) or with additional Zn (CRD + Zn, 30.3 ± 0.60 ppm) or biofortified rice diet (BRD; 8.54 ± 0.51 ppm) for 3 weeks. Body weights, plasma, liver, pancreatic, fecal Zn levels, and intestinal ZIP4 and ZnT1 mRNA expression were measured at the end of the experiment. The body weight of rats fed on CRD or CRD + Zn or BRD significantly increased (p < 0.01) compared to rats fed on ZDD. The body weight BRD was significantly higher compared to CRD (P < 0.01), both of which remained lower compared to CRD + Zn (p < 0.03). Repletion of Zn through either CRD or BRD significantly increased the plasma Zn concentration (PZC), tissue, and fecal Zn excretion compared to ZDD, without significant between-group differences. However, PZC, tissue, and fecal Zn of CRD + Zn was significantly higher compared to the rest of the groups. The intestinal ZIP4 and ZnT1 mRNA expressions are consistent with Zn status and/or dietary Zn exposure. A similar PZC, tissue, and fecal Zn in CRD compared to BRD, despite higher Zn intakes in the latter, could be due to preferential shuttling of Zn for growth. Together, these results indicate that Zn from biofortified rice is efficiently utilized for promoting the growth in Zn-deficient rats.