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

Abstract

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.

Comprehensive overview of the quality of plant‐ And animal‐sourced proteins based on the digestible indispensable amino acid score

“…During thermal processing, chemical reactions between reducing sugars and lysine lead to formation of Maillard reaction products. Such reactivity reduces the availability of lysine (Nyakayiru et al., 2020), hence the FAO recommendation for the use of digestible reactive lysine instead of total digestible lysine to determine the DIAAS. Such considerations will greatly affect the DIAAS value of protein, and possibly its limiting AA.…”

“…During thermal processing, chemical reactions between reducing sugars and lysine lead to formation of Maillard reaction products. Such reactivity reduces the availability of lysine (Nyakayiru et al, 2020), hence the FAO recom-…”

Casein Protein Processing Strongly Modulates Post-Prandial Plasma Amino Acid Responses In Vivo in Humans

“…Our data clearly demonstrate that food processing of protein ingredients can strongly modulate the post-prandial amino acid response to protein ingestion, even when micellar casein is used as the original protein source. Various forms of processing, such as heating, separation, added salts, cross-linking, drying, and glycation may all modulate the functional properties of dietary protein [43,44]. Furthermore, some of these processes may even occur during the storage of protein [40,41].…”

Dietary Advanced Glycation Endproducts and the Gastrointestinal Tract

“…A recent human trial administering milk protein to healthy young men, which was glycated to different extents, found a reduced lysine availability that was dose-dependent on the level of glycation. This reduced availability was only seen for lysine, not for the other amino acids [ 30 ]. Additionally, Joubran et al (2017) found that the MR changes the functionality of the whey protein α-lactalbumin.…”