Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.
Department of Pediatrics, School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada.
J Nutr. 2018 Jun 1;148(6):917-924. doi: 10.1093/jn/nxy039.
Maize is a staple food in many regions of the world, particularly in Africa and Latin America. However, maize protein is limiting in the indispensable amino acids lysine and tryptophan, making its protein of poor quality.
The main objective of this study was to determine the protein quality of white African cornmeal by determining the metabolic availability (MA) of lysine and tryptophan.
To determine the MA of lysine, 4 amounts of l-lysine (10, 13, 16, and 18 mg · kg-1 · d-1 totaling 28.6%, 37.1%, 45.7%, and 51.4% of the mean lysine requirement of 35 mg · kg-1 · d-1, respectively) were studied in 6 healthy young men in a repeated-measures design. To determine the MA of tryptophan, 4 amounts of l-tryptophan (0.5, 1, 1.5, and 2 mg · kg-1 · d-1 totaling 12.5%, 25.0%, 37.5%, and 50.0% of the mean tryptophan requirement of 4 mg · kg-1 · d-1, respectively) were studied in 7 healthy young men in a repeated-measures design. The MAs of lysine and tryptophan were estimated by comparing the indicator amino acid oxidation (IAAO) response with varying intakes of lysine and tryptophan in cooked white cornmeal compared with the IAAO response to l-lysine and l-tryptophan intakes in the reference protein (crystalline amino acid mixture patterned after egg protein) with the use of the slope ratio method.
The MAs of lysine and tryptophan from African cooked white cornmeal were 71% and 80%, respectively.
Our study provides a robust estimate of the availability of lysine and tryptophan in African white maize to healthy young men. This estimate provides a basis for postproduction fortification or supplementation of maize-based diets. This trial was registered at www.clinicaltrials.gov as NCT02402179.
玉米是世界上许多地区的主食，尤其是在非洲和拉丁美洲。然而，玉米蛋白在必需氨基酸赖氨酸和色氨酸方面是有限的，因此其蛋白质质量较差。
本研究的主要目的是通过测定赖氨酸和色氨酸的代谢可利用率（MA）来确定白非洲玉米粉的蛋白质质量。
为了测定赖氨酸的 MA，在 6 名健康年轻男性中以重复测量设计研究了 4 种 l-赖氨酸剂量（10、13、16 和 18mg·kg-1·d-1，分别占 35mg·kg-1·d-1 赖氨酸平均需求量的 28.6%、37.1%、45.7%和 51.4%）。为了测定色氨酸的 MA，在 7 名健康年轻男性中以重复测量设计研究了 4 种 l-色氨酸剂量（0.5、1、1.5 和 2mg·kg-1·d-1，分别占 4mg·kg-1·d-1 色氨酸平均需求量的 12.5%、25.0%、37.5%和 50.0%）。通过比较用煮熟的白玉米粉与用参考蛋白（根据卵蛋白模式设计的结晶氨基酸混合物）中 l-赖氨酸和 l-色氨酸摄入量的指示氨基酸氧化（IAAO）反应，来评估赖氨酸和色氨酸的 MA，用斜率比法。
白非洲玉米粉中赖氨酸和色氨酸的 MA 分别为 71%和 80%。
本研究为健康年轻男性提供了白非洲玉米中赖氨酸和色氨酸可用性的可靠估计。该估计为玉米基饮食的产后强化或补充提供了依据。本试验在 www.clinicaltrials.gov 上注册为 NCT02402179。
