Abstract The role of protein oxidation in the regulation of whole body protein metabolism is unknown. Previously, it was observed that vigorous exercise led to increased protein oxidation. To further characterise 13C-milk protein oxidation in healthy subjects, the oxidation of ingested 13C-protein after an overnight fast was measured using a non-invasive 13C-protein breath test. This approach enables the analysis of 13C-protein oxidation kinetics and the effect of interfering factors. It was found that the estimated maximal 13C-milk protein oxidation was 0.07 g min−1, corresponding to a theoretical maximal oxidation capacity of ≈1.4 g kg body weight−1 d−1. No indications were found for preferential oxidation of non-essential amino acids. Combined ingestion of 30 g 13C-whey protein with 30 g glucose resulted in a 19% decrease of 13C-whey protein oxidation. It was concluded that exogenous 13C-whey protein oxidation can be affected by other co-ingested nutrients like glucose.

中文翻译：

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健康受试者的牛奶蛋白氧化：初步研究

摘要 蛋白质氧化在调节全身蛋白质代谢中的作用尚不清楚。以前，据观察，剧烈运动会导致蛋白质氧化增加。为了进一步表征健康受试者中 13C-牛奶蛋白的氧化，使用非侵入性 13C-蛋白呼气试验测量禁食过夜后摄入的 13C-蛋白的氧化。这种方法可以分析 13C 蛋白质氧化动力学和干扰因素的影响。发现估计的最大 13C 牛奶蛋白质氧化为 0.07 g min-1，对应于 ≈1.4 g kg 体重-1 d-1 的理论最大氧化能力。没有发现优先氧化非必需氨基酸的迹象。将 30 克 13C-乳清蛋白与 30 克葡萄糖联合摄入可使 13C-乳清蛋白氧化减少 19%。得出的结论是，外源性 13C-乳清蛋白氧化会受到其他共同摄入的营养物质（如葡萄糖）的影响。