Background: The bioconversion efficiency of yellow maize ß-carotene to retinol in humans is unknown.
Objective: The objective of this study was to determine the vitamin A value of yellow maize ß-carotene in humans.
Design: High ß-carotene–containing yellow maize was grown in a hydroponic medium with 23 atom% 2H2O during grain development. Yellow maize ß-carotene showed the highest abundance of enrichment as [2H9]ß-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 ß-carotene, 20 g butter, and a 0.5-g corn oil capsule. On day 8, fasting blood was drawn, and subjects consumed 1 mg [13C10]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 ß-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 ß-carotene was 72.9 nmol · d, and the AUC of retinol from 1 mg retinyl acetate 13C10 was 161.1 nmol · d. The conversion factor of yellow maize ß-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 ß-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.
Muzhingi, T.; Gadaga, T.H.; Siwela, A.H.; Grusak, M.A.; Russell, R.M.; Tang GuangWen. Yellow maize with high beta-carotene is an effective source of vitamin A in healthy Zimbabwean men. American Journal of Clinical Nutrition (2011) 94 (2) 510-519. [DOI: 10.3945/ajcn.110.006486]