The effect of a blade tenderized steak, infused with hydrolyzed proteins on amino acid kinetics in young and elderly men and women

Abstract

Background: Sarcopenia is the age-related loss of skeletal muscle mass, which is believed to be, at least partly, caused by anabolic resistance due to changes in amino acid (AA) kinetics after ingestion of proteins. Aging is accompanied with challenges to ingest, digest and absorb enough proteins to maintain skeletal muscle mass. Modifications to intact food like, changing the texture, protein supplementation or ingestions hydrolysed proteins have been shown to be beneficial for the elderly’s anabolic stimuli to protein ingestion. The purpose of this study was to investigate the effect of a blade tenderized steak, infused with hydrolysed proteins, on AA kinetics in healthy elderly men and woman and compare with the kinetics in healthy young participants.

Method: 15 young (20-40y) and 13 elderly (70-80 y) met twice in the lab to ingest a nonmodified and a modified steak, combined in a mixed meal. Blood samples were withdrawn at 6 timepoints (1 pre, 5 post ingestion) and analysed for glucose-, insulin, and AAconcentration.

Results: Both steaks raised the blood concentration of essential AA (EAA) and non-essential AA (NEAA), but there were no significant differences between the modified and the nonmodified product. However, there was a trend to a more rapid increase in blood concentrations of AAs, in the young after ingesting the modified meal compared to the nonmodified meal. The young had higher baseline values of leucine (28.5%), branch-chained amino acids (BCAA)(30.9%), and EAA(21.5%) which resulted in higher area under the curve (AUC) in the young due to similar increases in these AAs after ingestion.

Conclusion: The modifications to the steak did not cause any significant impact on the AA profile. However, there was a trend to a more rapid increase in AAs in the young after ingestion of the modified meal compared to the non-modified meal. Elderly displayed lower baseline concentrations of leucine, BCAA, and EAA, but not NEAA. The relative increase in AA concentrations after the meals were not different between young old and young, but the lower baseline concentrations lead to lower absolute concentrations of these AAs after ingestion of proteins, which may affect the anabolic response to protein ingestion.