| Zinc is an essential nutrient that is required for growth, immunity, and reproduction. Staple foods, such as rice, may be enriched with zinc through fortification to enhance dietary intake of zinc. However, most short-term studies of cereal fortification in young children have failed to detect an increase in serum zinc concentration, which differs from the results of supplementation trials. The purpose of this study was to compare the post-absorptive localization of additional zinc provided in fortified rice slurry or as a zinc supplement in weanling rats. Ten groups (n=8 pups, 4m/4f) were assigned one of five diets (Zinc Supplementation or a Rice Slurry without Fortification, Low Fortification, Medium Fortification, or High Fortification with zinc). Within each diet group, one sub-group was killed 6 h and the other group 54 h after the administration of the meal. Total absorbed zinc (TAZ) increased significantly (p<0.05) with increasing zinc intake from the fortified rice slurry. At both 6 h and 54 h following meal administration by oral gavage, a higher percent of absorbed or retained zinc in the Rice Slurry with High Zn Fortification groups were localized to the blood (per 1 g) and muscle (per 1 g) compared to the rice slurries without fortification, with Low Zn Fortification, or with Medium Zn Fortification (p<0.05). At 6 h, but not 54 h, post-gavage, TAZ for body weight was greater from the supplement than from the fortificant (interpolated to match the amount of zinc delivered in the supplement). Of the zinc absorbed at 6 h post-gavage, a higher proportion of zinc from the fortificant was localized to the kidney and intestinal tissue while a higher proportion of zinc from the supplement was localized to the carcass and muscle. Although a higher proportion of zinc from the supplement remained in circulation in the blood compared to the fortificant at 6 hours, the difference was not statistically significant (p=0.110). However, of the zinc that was retained at 54 h post-gavage, a higher proportion of zinc from the supplement remained in circulation in the blood compared to the fortificant (p=0.024). This suggests that the distribution of absorbed zinc differs with the level of zinc fortification and the mode of administration may have implications for supplementation and fortification policies. |
