Postprandial muscle protein synthesis rate is unaffected by 20-day habituation to a high protein intake: a randomized controlled, crossover trial

Grith Højfeldt*, Jacob Bülow, Jakob Agergaard, Lene R. Simonsen, Jens Bülow, Peter Schjerling, Gerrit van Hall, Lars Holm

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

2 Citations (Scopus)

Abstract

Purpose: During the last decade more researchers have argued in favor of an increased protein intake for older adults. However, there is a lack of knowledge on the long-term effects of conforming to such a high protein intake with regards to the basal and postprandial muscle protein turnover. The purpose of this study was to compare the postprandial synthesis response in muscle proteins, and the abundance of directly incorporated food-derived amino acids following habituation to high vs. recommended level of protein intake. Methods: In a double blinded crossover intervention 11 older male participants (66.6 ± 1.7 years of age) were habituated for 20 days to a recommended protein (RP) intake (1.1 g protein/kg lean body mass (LBM)/day) and a high protein (HP) intake (> 2.1 g protein/kg LBM/day). Following each habituation period, intrinsically labelled proteins were ingested as part of a mixed meal to determine the incorporation of meal protein-derived amino acids into myofibrillar proteins. Furthermore, the myofibrillar fractional synthesis rate (FSR) and amino acid kinetics across the leg were determined using gold standard stable isotope tracer methodologies. RT qPCR was used to assess the expression of markers related to muscle proteinsynthesis and breakdown. Results: No impact of habituation was observed on skeletal muscle amino acid or protein kinetics. However, the shunting of amino acids directly from artery to vein was on average 2.9 μ mol/min higher following habituation to HP compared to RP. Conclusions: In older males, habituation to a higher than the currently recommended protein intake did not demonstrate any adaptions in the muscle protein turnover or markers hereof when subjected to an intake of an identical mixed meal. Clinical Trial Registry: Journal number NCT02587156, Clinicaltrials.org. Date of registration: October 27th, 2015.

Original languageEnglish
JournalEuropean Journal of Nutrition
Volume60
Pages (from-to)4307-4319
ISSN1436-6207
DOIs
Publication statusPublished - 2021

Bibliographical note

Publisher Copyright:
© 2021, Springer-Verlag GmbH Germany, part of Springer Nature.

Keywords

  • Fractional synthesis rate
  • Habituated protein intake
  • High protein intake
  • Intrinsically labelled proteins
  • Protein breakdown
  • Protein synthesis
  • Recommended protein intake

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