TY - JOUR

T1 - Even or skewed dietary protein distribution is reflected in the whole-body protein net-balance in healthy older adults

T2 - A randomized controlled trial

AU - Agergaard, Jakob

AU - Justesen, Thomas Ehlig Hjermind

AU - Jespersen, Simon Elmer

AU - Tagmose Thomsen, Thomas

AU - Holm, Lars

AU - van Hall, Gerrit

N1 - Publisher Copyright: © 2023 The Authors

PY - 2023

Y1 - 2023

N2 - Background & aim: For older adults, the dietary protein intake has shown to be skewed towards the evening meal. Resultingly, the vital source of essential amino acids could be insufficient after some meals, while after the evening meal the dietary protein could be suboptimally utilized for protein synthesis. The present study explored if an even distribution of the protein intake could improve the dietary amino acid absorption and whole-body protein net-balance. Methods: Twenty-four healthy elderly males and females were included in a randomized controlled trial. Ten days of habituation to either an EVEN (n = 12) or SKEWED (n = 12) protein intake, was followed by a trial day. The total protein intake was controlled at 1.5 g/kg LBM, divided into 30% at each main meal in EVEN, and into 15% at breakfast and lunch and 60% at dinner in SKEWED. Snacks with 5% of the protein intake were served between meals. Energy intake in the meals and snacks were equal in both groups. Intrinsically labelled 2H5-phenylalanine minced meat was served as the dietary protein to assess the amino acid absorption. On the trial day, infusion of 2H8-phenylalanine and 2H2-tyrosine, and blood samples taken over 11 h were used to measure whole-body protein turnover. Vastus lateralis muscle biopsies were taken to measure 9 h muscle protein FSR. Results: Amino acid absorption rates and concentrations were greater in EVEN compared to SKEWED protein intake. Whole-body protein breakdown rates were lower with similar protein synthesis rates, and consequently the net-balance was greater in EVEN after breakfast and lunch compared to SKEWED and were the same in both groups after dinner. Muscle protein FSR were not different between EVEN and SKEWED. Conclusions: The whole-body protein net-balance was more positive in EVEN compared to SKEWED for an extended time of the measured period, driven by a lower whole-body protein breakdown in EVEN. Clinical Trials registration: NCT03870425, https://clinicaltrials.gov/ct2/show/NCT03870425.

AB - Background & aim: For older adults, the dietary protein intake has shown to be skewed towards the evening meal. Resultingly, the vital source of essential amino acids could be insufficient after some meals, while after the evening meal the dietary protein could be suboptimally utilized for protein synthesis. The present study explored if an even distribution of the protein intake could improve the dietary amino acid absorption and whole-body protein net-balance. Methods: Twenty-four healthy elderly males and females were included in a randomized controlled trial. Ten days of habituation to either an EVEN (n = 12) or SKEWED (n = 12) protein intake, was followed by a trial day. The total protein intake was controlled at 1.5 g/kg LBM, divided into 30% at each main meal in EVEN, and into 15% at breakfast and lunch and 60% at dinner in SKEWED. Snacks with 5% of the protein intake were served between meals. Energy intake in the meals and snacks were equal in both groups. Intrinsically labelled 2H5-phenylalanine minced meat was served as the dietary protein to assess the amino acid absorption. On the trial day, infusion of 2H8-phenylalanine and 2H2-tyrosine, and blood samples taken over 11 h were used to measure whole-body protein turnover. Vastus lateralis muscle biopsies were taken to measure 9 h muscle protein FSR. Results: Amino acid absorption rates and concentrations were greater in EVEN compared to SKEWED protein intake. Whole-body protein breakdown rates were lower with similar protein synthesis rates, and consequently the net-balance was greater in EVEN after breakfast and lunch compared to SKEWED and were the same in both groups after dinner. Muscle protein FSR were not different between EVEN and SKEWED. Conclusions: The whole-body protein net-balance was more positive in EVEN compared to SKEWED for an extended time of the measured period, driven by a lower whole-body protein breakdown in EVEN. Clinical Trials registration: NCT03870425, https://clinicaltrials.gov/ct2/show/NCT03870425.

KW - Dietary protein

KW - Muscle protein synthesis

KW - Older adults

KW - Protein distribution

KW - Protein turnover

UR - http://www.scopus.com/inward/record.url?scp=85152746691&partnerID=8YFLogxK

U2 - 10.1016/j.clnu.2023.04.004

DO - 10.1016/j.clnu.2023.04.004

M3 - Journal article

C2 - 37086618

AN - SCOPUS:85152746691

VL - 42

SP - 899

EP - 908

JO - Clinical Nutrition

JF - Clinical Nutrition

SN - 0261-5614

IS - 6

ER -