Iron and Zinc Bioavailability from Madhukar × Swarna Derived Biofortifed Rice Lines

Rice is the prime target of biofortification as it provides calories for about half of the world’s population. We assessed the iron (Fe) and zinc (Zn) bioavailability from polished rice grains of three high Fe and Zn recombinant inbred lines (RILs) using simulated in vitro digestion/Caco-2 cell model. Ferritin induction and ⁶⁵Zn uptake were used as surrogate for Fe and Zn bioavailability respectively. Fe and Zn concentration in both unpolished and polished rice grains of three RILs was higher compared to Swarna, a parent and popular variety used as control. The grain Fe concentration was positively correlated (r = 0.94) to Zn concentration. There was a 2-fold induction of ferritin (42.4 ± 3.2 ng/mg protein) in Caco-2 cells only in the presence of ascorbic acid and 3-fold increase in ⁶⁵Zn uptake (17.7 ± 2.4 pmol/mg protein) from the RIL 185M compared to Swarna (ferritin: 24.8 ± 4.0 ng/mg protein; ⁶⁵Zn uptake: 5.8 ± 0.3 pmol/mg protein). Phytic acid was highest (8.75 mg/g) in 185 M but that did not affect bioavailability of Fe and Zn. Thus, improving the density of Fe and Zn in grains of conventionally bred rice lines has the potential to enhance the bioavailability of Fe and Zn.