Golden Rice is an effective source of vitamin A.
BACKGROUND
Genetically engineered "Golden Rice" contains up to 35 microg beta-carotene per gram of rice. It is important to determine the vitamin A equivalency of Golden Rice beta-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.


METHODS
Golden Rice plants were grown hydroponically with heavy water (deuterium oxide) to generate deuterium-labeled [2H]beta-carotene in the rice grains. Golden Rice servings of 65-98 g (130-200 g cooked rice) containing 0.99-1.53 mg beta-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 microg x d after the Golden Rice dose. Compared with that of the [13C10]retinyl acetate reference dose (84.7 +/- 34.6 microg x d), Golden Rice beta-carotene provided 0.24-0.94 mg retinol. Thus, the conversion factor of Golden Rice beta-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.


CONCLUSIONS
Beta-carotene derived from Golden Rice is effectively converted to vitamin A in humans. This trial was registered at clinicaltrials.gov as NCT00680355.
Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA. guangwen.tang@tufts.edu
Guangwen
G
Tang
Jian
J
Qin
Gregory G
GG
Dolnikowski
Robert M
RM
Russell
Michael A
MA
Grusak
D000328:Adult; D000368:Aged; D019540:Area Under Curve; D004224:Diterpenes; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012275:Oryza / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D012016:Reference Values; D000084562:Retinyl Esters; D014801:Vitamin A / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000097:blood* / Q000378:metabolism; D014802:Vitamin A Deficiency / Q000517:prevention & control; D014815:Vitamins / Q000097:blood / Q000378:metabolism*; D019207:beta Carotene / Q000032:analysis / Q000378:metabolism*
D004224:Diterpenes; D000084562:Retinyl Esters; D014815:Vitamins; D019207:beta Carotene; D014801:Vitamin A; C009166:retinol acetate