The glycation level of milk protein strongly modulates post-prandial lysine availability in humans

• Published in: British journal of nutrition 2020-03, Vol.123 (5), p.545-552
• Main Authors: Nyakayiru, Jean, van Lieshout, Glenn A A, Trommelen, Jorn, van Kranenburg, Janneau, Verdijk, Lex B, Bragt, Marjolijn C E, van Loon, Luc J C
• Format: Article
• Language: English
• Subjects: amino acid composition; Amino acids; Availability; bioavailability; blood plasma; blood sampling; body mass index; cross-over studies; essential amino acids; glycation; Glycosylation; Heat treatment; Human and Clinical Nutrition; Ingestion; Lactose; Liquid chromatography; Lysine; Medical screening; men; Milk; milk consumption; milk proteins; postprandial state; protein intake; Protein sources; Protein synthesis; Proteins; ultra-performance liquid chromatography
• ISSN: 0007-1145; 1475-2662; 1475-2662
• DOI: 10.1017/S0007114519002927

Industrial heat treatment of milk results in protein glycation. A high protein glycation level has been suggested to compromise the post-prandial rise in plasma amino acid availability following protein ingestion. In the present study, we assessed the impact of glycation level of milk protein on post-prandial plasma amino acid responses in humans. Fifteen healthy, young men (age 26 (SEM 1) years, BMI 24 (SEM 1) kg/m2) participated in this randomised cross-over study and ingested milk protein powder with protein glycation levels of 3, 20 and 50 % blocked lysine. On each trial day, arterialised blood samples were collected at regular intervals during a 6-h post-prandial period to assess plasma amino acid concentrations using ultra-performance liquid chromatography. Plasma essential amino acid (EAA) concentrations increased following milk protein ingestion, with the 20 and 50 % glycated milk proteins showing lower overall EAA responses compared with the 3 % glycated milk protein (161 (SEM 7) and 142 (SEM 7) v. 178 (SEM 9) mmol/l × 6 h, respectively; P ≤ 0·011). The lower post-prandial plasma amino acid responses were fully attributed to an attenuated post-prandial rise in circulating plasma lysine concentrations. Plasma lysine responses (incremental AUC) following ingestion of the 20 and 50 % glycated milk proteins were 35 (SEM 4) and 92 (SEM 2) % lower compared with the 3 % glycated milk protein (21·3 (SEM 1·4) and 2·8 (SEM 0·7) v. 33·3 (SEM 1·7) mmol/l × 6 h, respectively; P < 0·001). Milk protein glycation lowers post-prandial plasma lysine availability in humans. The lower post-prandial availability of lysine following ingestion of proteins with a high glycation level may compromise the anabolic properties of a protein source.