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.