Yellow maize with high β-carotene is an effective source of vitamin A in healthy Zimbabwean men

Abstract

Background: The bioconversion efficiency of yellow maize β-carotene to retinol in humans is unknown. Objective: The objective of this study was to determine the vitamin A value of yellow maize β-carotene in humans. Design: High β-carotene - containing yellow maize was grown in a hydroponic medium with 23 atom% 2H 2O during grain development. Yellow maize β-carotene showed the highest abundance of enrichment as [ 2H 9]β-carotene. Eight healthy Zimbabwean men volunteered for the study. On day 1 after a fasting blood draw, subjects consumed 300 g yellow maize porridge containing 1.2 mg β-carotene, 20 g butter, and a 0.5-g corn oil capsule. On day 8, fasting blood was drawn, and subjects consumed 1 mg [ 13C 10]retinyl acetate in a 0.5-g corn oil capsule and 300 g white maize porridge with 20 g butter. Thirty-six blood samples were collected from each subject over 36 d. Concentrations and enrichments of retinol and β-carotene in labeled doses and serum were determined with the use of HPLC, gas chromatography - mass spectrometry, and liquid chromatography - mass spectrometry. Results: The area under the curve (AUC) of retinol from 1.2 mg yellow maize β-carotene was 72.9 nmol • d, and the AUC of retinol from 1 mg retinyl acetate 13C 10 was 161.1 nmol • d. The conversion factor of yellow maize β-carotene to retinol by weight was 3.2 ± 1.5 to 1. Conclusion: In 8 healthy Zimbabwean men, 300 g cooked yellow maize containing 1.2 mg β-carotene that was consumed with 20.5 g fat showed the same vitamin A activity as 0.38 mg retinol and provided 40-50% of the adult vitamin A Recommended Dietary Allowance. This trial was registered at clinicaltrials.gov as NCT00636038. © 2011 American Society for Nutrition.