Golden Rice is an effective source of vitamin A
2009
Tang, Guangwen | Qin, Jian | Dolnikowski, Gregory G. | Russell, Robert M. | Grusak, Michael A.
BACKGROUND: Genetically engineered "Golden Rice" contains up to 35 μg β-carotene per gram of rice. It is important to determine the vitamin A equivalency of Golden Rice β-carotene to project the potential effect of this biofortified grain in rice-consuming populations that commonly exhibit low vitamin A status. OBJECTIVE: The objective was to determine the vitamin A value of intrinsically labeled dietary Golden Rice in humans. DESIGN: Golden Rice plants were grown hydroponically with heavy water (deuterium oxide) to generate deuterium-labeled [²H]β-carotene in the rice grains. Golden Rice servings of 65-98 g (130-200 g cooked rice) containing 0.99-1.53 mg β-carotene were fed to 5 healthy adult volunteers (3 women and 2 men) with 10 g butter. A reference dose of [¹³C₁₀]retinyl acetate (0.4-1.0 mg) in oil was given to each volunteer 1 wk before ingestion of the Golden Rice dose. Blood samples were collected over 36 d. RESULTS: Our results showed that the mean (±SD) area under the curve for the total serum response to [²H]retinol was 39.9 ± 20.7 μg·d after the Golden Rice dose. Compared with that of the [¹³C₁₀]retinyl acetate reference dose (84.7 ± 34.6 μg·d), Golden Rice β-carotene provided 0.24-0.94 mg retinol. Thus, the conversion factor of Golden Rice β-carotene to retinol is 3.8 ± 1.7 to 1 with a range of 1.9-6.4 to 1 by weight, or 2.0 ± 0.9 to 1 with a range of 1.0-3.4 to 1 by moles. CONCLUSION: β-Carotene derived from Golden Rice is effectively converted to vitamin A in humans. This trial was registered at clinicaltrials.gov as NCT00680355.
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