BC Children's Hospital Research Institute, BC Children's Hospital, Vancouver, British Columbia, Canada; Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada; Faculty of Applied Medical Sciences, Department of Clinical Nutrition, King Abdulaziz University, Jeddah, Saudi Arabia.
BC Children's Hospital Research Institute, BC Children's Hospital, Vancouver, British Columbia, Canada; Department of Pediatrics, University of British Columbia, Vancouver, Canada.
Mol Genet Metab. 2022 Jan;135(1):56-62. doi: 10.1016/j.ymgme.2021.12.013. Epub 2021 Dec 23.
Propionic Acidemia (PROP) is an inherited metabolic disorder, with defect in the enzyme propionyl-CoA carboxylase (PCC) which catalyzes catabolism of two of the branched-chain amino acids (BCAA), valine, isoleucine. Nutritional management in PROP depends on dietary protein restriction and consumption of medical formula depleted of the offending amino acids. Recently, concerns have been raised about medical formula due to imbalanced content of BCAA (high leucine - another BCAA, and no valine/isoleucine), which negatively impacts plasma concentrations of BCAA, and growth in children with PROP.
To determine an optimal BCAA ratio at which total body protein synthesis is optimized in healthy children using the indicator amino acid oxidation method (oxidation of L-C-Phenylalanine to CO). This was accomplished by reducing leucine intake gradually from the current high dose in medical formula, in order to compare protein synthesis, under different BCAA ratios.
A total of 8 healthy children were studied, completing 42 study days. Significant differences in FCO with different BCAA ratios were found. BCAA ratio (leucine: isoleucine: valine) 1:0:0 was associated with the highest FCO (low protein synthesis) compared to other ratios. By reducing leucine intake, and isoleucine and valine at minimum PROP recommendations, BCAA ratio between1:0.26:0.28 to 1:0.35:0.4 was associated with optimal protein synthesis.
BCAA ratio of 1:0:0, present in medical formula limited total body protein synthesis. A balanced BCAA ratio was found between 1:0.26:0.28 and 1:0.35:0.4 (leucine:isoleucine:valine). Future research is needed to test this optimal BCAA ratio for optimizing protein synthesis in patients with PROP.
The article describes a proof-of-concept study done on healthy school-aged children testing different ratios of branched chain amino acid (BCAA, leucine:isoleucine:valine), in order to determine an optimal ratio at which total body protein synthesis is improved and has implications for dietary management of children with Propionic Acidemia (PROP).
丙酸血症（PROP）是一种遗传性代谢疾病，其缺陷酶为丙酰基辅酶 A 羧化酶（PCC），该酶催化两种支链氨基酸（BCAA），即缬氨酸和异亮氨酸的分解代谢。PROP 的营养管理依赖于饮食中蛋白质的限制和摄入不含致病氨基酸的医学配方。最近，由于医学配方中 BCAA（高亮氨酸-另一种 BCAA，没有缬氨酸/异亮氨酸）含量不平衡，对医学配方的担忧已经出现，这会对 PROP 儿童的血浆 BCAA 浓度和生长产生负面影响。
使用指示氨基酸氧化法（L-C-苯丙氨酸氧化为 CO），确定健康儿童中总蛋白合成优化的最佳 BCAA 比例。通过逐渐减少医学配方中目前高剂量的亮氨酸摄入来实现这一目标，以便比较不同 BCAA 比例下的蛋白质合成。
共有 8 名健康儿童参与了研究，完成了 42 天的研究。发现不同 BCAA 比例下 FCO 有显著差异。与其他比例相比，BCAA 比例（亮氨酸：异亮氨酸：缬氨酸）1:0:0 与 FCO 最高（低蛋白合成）相关。通过减少亮氨酸摄入，并按照 PROP 的最低推荐量摄入异亮氨酸和缬氨酸，BCAA 比例在 1:0.26:0.28 至 1:0.35:0.4 之间与最佳蛋白质合成相关。
医学配方中的 BCAA 比例 1:0:0 限制了总体蛋白合成。发现 BCAA 比例在 1:0.26:0.28 与 1:0.35:0.4（亮氨酸：异亮氨酸：缬氨酸）之间平衡。需要进一步研究来测试这种最佳 BCAA 比例是否可以优化 PROP 患者的蛋白质合成。
本文描述了一项针对健康学龄儿童的概念验证研究，测试了不同的支链氨基酸（BCAA，亮氨酸：异亮氨酸：缬氨酸）比例，以确定总体蛋白合成改善的最佳比例，并对丙酸血症（PROP）儿童的饮食管理有影响。
