Quantifying the Bioefficacy of β‐Carotene‐biofortified Sorghum Using a Mongolian Gerbil Model

β‐Carotene‐biofortified transgenic sorghum is being developed to alleviate vitamin A deficiency in semiarid regions of Africa. Our objective was to quantify the bioefficacy of the biofortified sorghum using a Mongolian gerbil model. Gerbils were fed a vitamin A (VA)‐free control diet (45% by wt non‐transgenic sorghum flour) for 4 wk; 8 animals were then killed at baseline. The remaining animals were randomly assigned to treatments for 6 wk (n = 11 per group): 1) control diet dosed daily with cottonseed oil vehicle; 2) biofortified diet (45% by wt transgenic sorghum flour) dosed daily with cottonseed oil vehicle (95.8 nmol retinol equivalents/d); 3) control diet dosed daily with β‐carotene (84.5 nmol retinol equivalents/d); 4) control diet dosed daily with VA (84.5 nmol retinol equivalents/d). Liver VA stores in the baseline (1.27 ± 0.29 μmol), β‐carotene‐dosed (1.30 ± 0.26 μmol), and biofortified (1.31 ± 0.23 μmol) groups were not different; liver stores in the vehicle‐dosed control group were lower (0.92 ± 0.22 μmol) (P < 0.03). Liver stores were highest in the VA‐dosed group (2.48 ± 0.23 μmol) (P < 0.0001). The calculated bioconversion efficiency for the β‐carotene in the biofortified sorghum (4.3 μg β‐carotene to 1 μg retinol) was similar to that of the β‐carotene dose (3.8 μg to 1 μg retinol). The β‐carotene in the biofortified sorghum effectively restored liver vitamin A stores in an animal model.