Bioavailability of Golden Rice Carotenoids in Humans

Overview

This investigation protocol uses an isotope reference method to evaluate bioavailability of ß-C in rice and its bioconversion to vitamin A. A well-nourished population will be fed hydroponically grown Golden Rice containing \~ 1 mg of β-carotene at day 8 after a reference dose of vitamin A at day 1. The blood samples will be collected up to 33 days after the doses. The absorption kinetics will be determined by tracking both vitamin A and β-carotene in human serum. Blood responses to Golden Rice β-carotene will be determined and evaluated. The vitamin A value of Golden Rice can thus be quantitatively determined.

Recently, scientists have genetically engineered "golden rice" that contains 1.6 ug ß-carotene in a gram of dry rice (12). Since the vitamin A equivalency varies from 2 ug (oil dose) to 27 ug (vegetable) carotene to 1 retinol equivalent and the equivalency is matrix dependent, it is necessary to know what the vitamin A equivalency of golden rice beta-carotene is. The determination of the absorption and conversion of golden rice beta-carotene is of importance for designing food programs in many rice-eating regions of the world, where vitamin A deficiency is common. To evaluate the absorption and intestinal conversion of rice beta-carotene after an acute dose of golden rice, an intrinsically labeled Golden Rice with a labeled reference dose of vitamin A are used. We propose to conduct a pilot study on the US adults with normal vitamin A status (n = 15). The specific aims of this pilot study are: 1. To determine ß-carotene response kinetics following a meal of golden rice with 0, 5, or 10 g fat (butter); 2. To determine retinol kinetics from the golden rice and from the labeled vitamin A dose; 3. To determine vitamin A value of golden rice ß-carotene in adults with normal vitamin A status. The determination of the absorption and conversion of golden rice ß-carotene is of importance for designing food programs in many rice-eating regions of the world, where vitamin A deficiency is common.

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