Vitamin A (VA)-fortified rice is a potential intervention strategy to prevent VA deficiency in at-risk populations. Hot-extruded, triple-fortified rice grains with added VA, zinc, and iron were produced by hot extrusion technology and their ability to improve VA status was tested in Thai schoolchildren. The fortification levels were 10 mg of iron, 9 mg of zinc, and 1.05 mg of VA/g extruded rice. A paired stable isotope dilution technique with labeled ¹³C₂-retinyl acetate (¹³C-RID) was used to quantify VA pool size at the beginning and end of the feeding period. Fifty healthy schoolchildren with a serum retinol (SR) concentration of >0.7 μmol/L were randomly assigned to 2 groups to receive either triple-fortified rice (n = 25) or natural rice (n = 25) for 2 mo as part of the daily school meal. The fortified grains, mixed 1:50 with regular rice, were estimated to provide an extra 890 μg of VA/d, 5 d/wk. ¹³C₂-retinyl acetate (1.0 μmol) was administered orally to each child before and at the end of the feeding period to estimate total body reserves (TBRs) of VA, which increased significantly (P < 0.05) in the intervention group from 153 ± 66 μmol retinol at baseline to 269 ± 148 μmol retinol after 2 mo of feeding. There was no change in the TBRs of VA in the control group (108 ± 67 vs. 124 ± 89 μmol retinol) (P = 0.22). Serum retinol remained unchanged in both groups. We conclude that VA-fortified, hot-extruded rice is an efficacious vehicle to provide additional VA to at-risk populations, and that the efficacy of VA-fortified foods can be usefully monitored by the ¹³C-RID measurement of TBRs of VA but not by changes in SR concentration.
Trial registration: ClinicalTrials.gov NCT01199445.