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Højfeldt G, Bülow J, Agergaard J, Simonsen LR, Bülow J, Schjerling P, van Hall G, Holm L. Postprandial muscle protein synthesis rate is unaffected by 20-day habituation to a high protein intake: a randomized controlled, crossover trial. Eur J Nutr 2021; 60:4307-4319. [PMID: 34032900 DOI: 10.1007/s00394-021-02590-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 05/12/2021] [Indexed: 11/29/2022]
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 [Formula: see text]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.
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Affiliation(s)
- Grith Højfeldt
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark.
| | - Jacob Bülow
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
| | - Jakob Agergaard
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
| | - Lene R Simonsen
- Department of Clinical Physiology and Nuclear Medicine, Bispebjerg and Frederiksberg Hospital, Frederiksberg, Denmark
| | - Jens Bülow
- Department of Clinical Physiology and Nuclear Medicine, Bispebjerg and Frederiksberg Hospital, Frederiksberg, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Peter Schjerling
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark.,Center for Healthy Aging, Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Gerrit van Hall
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Clinical Metabolomics Core Facility, Department of Biochemistry, Rigshospitalet, Copenhagen, Denmark
| | - Lars Holm
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
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