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Ingestion of Free Amino Acids Compared with an Equivalent Amount of Intact Protein Results in More Rapid Amino Acid Absorption and Greater Postprandial Plasma Amino Acid Availability Without Affecting Muscle Protein Synthesis Rates in Young Adults in a Double-Blind Randomized Trial
BACKGROUND: The rate of protein digestion and amino acid absorption determines the postprandial rise in circulating amino acids and modulates postprandial muscle protein synthesis rates. OBJECTIVE: We sought to compare protein digestion, amino acid absorption kinetics, and the postprandial muscle pr...
Autores principales: | , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Oxford University Press
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8754581/ https://www.ncbi.nlm.nih.gov/pubmed/34642762 http://dx.doi.org/10.1093/jn/nxab305 |
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author | Weijzen, Michelle E G van Gassel, Rob J J Kouw, Imre W K Trommelen, Jorn Gorissen, Stefan H M van Kranenburg, Janneau Goessens, Joy P B van de Poll, Marcel C G Verdijk, Lex B van Loon, Luc J C |
author_facet | Weijzen, Michelle E G van Gassel, Rob J J Kouw, Imre W K Trommelen, Jorn Gorissen, Stefan H M van Kranenburg, Janneau Goessens, Joy P B van de Poll, Marcel C G Verdijk, Lex B van Loon, Luc J C |
author_sort | Weijzen, Michelle E G |
collection | PubMed |
description | BACKGROUND: The rate of protein digestion and amino acid absorption determines the postprandial rise in circulating amino acids and modulates postprandial muscle protein synthesis rates. OBJECTIVE: We sought to compare protein digestion, amino acid absorption kinetics, and the postprandial muscle protein synthetic response following ingestion of intact milk protein or an equivalent amount of free amino acids. METHODS: Twenty-four healthy, young participants (mean ± SD age: 22 ± 3 y and BMI 23 ± 2 kg/m(2); sex: 12 male and 12 female participants) received a primed continuous infusion of l-[ring-(2)H(5)]-phenylalanine and l-[ring-3,5–(2)H(2)]-tyrosine, after which they ingested either 30 g intrinsically l-[1–(13)C]-phenylalanine–labeled milk protein or an equivalent amount of free amino acids labeled with l-[1–(13)C]-phenylalanine. Blood samples and muscle biopsies were obtained to assess protein digestion and amino acid absorption kinetics (secondary outcome), whole-body protein net balance (secondary outcome), and mixed muscle protein synthesis rates (primary outcome) throughout the 6-h postprandial period. RESULTS: Postprandial plasma amino acid concentrations increased after ingestion of intact milk protein and free amino acids (both P < 0.001), with a greater increase following ingestion of the free amino acids than following ingestion of intact milk protein (P-time × treatment < 0.001). Exogenous phenylalanine release into plasma, assessed over the 6-h postprandial period, was greater with free amino acid ingestion (76 ± 9%) than with milk protein treatment (59 ± 10%; P < 0.001). Ingestion of free amino acids and intact milk protein increased mixed muscle protein synthesis rates (P-time < 0.001), with no differences between treatments (from 0.037 ± 0.015%/h to 0.053 ± 0.014%/h and 0.039 ± 0.016%/h to 0.051 ± 0.010%/h, respectively; P-time × treatment = 0.629). CONCLUSIONS: Ingestion of a bolus of free amino acids leads to more rapid amino acid absorption and greater postprandial plasma amino acid availability than ingestion of an equivalent amount of intact milk protein. Ingestion of free amino acids may be preferred over ingestion of intact protein in conditions where protein digestion and amino acid absorption are compromised. |
format | Online Article Text |
id | pubmed-8754581 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Oxford University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-87545812022-01-14 Ingestion of Free Amino Acids Compared with an Equivalent Amount of Intact Protein Results in More Rapid Amino Acid Absorption and Greater Postprandial Plasma Amino Acid Availability Without Affecting Muscle Protein Synthesis Rates in Young Adults in a Double-Blind Randomized Trial Weijzen, Michelle E G van Gassel, Rob J J Kouw, Imre W K Trommelen, Jorn Gorissen, Stefan H M van Kranenburg, Janneau Goessens, Joy P B van de Poll, Marcel C G Verdijk, Lex B van Loon, Luc J C J Nutr Nuclear Techniques in Nutrition Research BACKGROUND: The rate of protein digestion and amino acid absorption determines the postprandial rise in circulating amino acids and modulates postprandial muscle protein synthesis rates. OBJECTIVE: We sought to compare protein digestion, amino acid absorption kinetics, and the postprandial muscle protein synthetic response following ingestion of intact milk protein or an equivalent amount of free amino acids. METHODS: Twenty-four healthy, young participants (mean ± SD age: 22 ± 3 y and BMI 23 ± 2 kg/m(2); sex: 12 male and 12 female participants) received a primed continuous infusion of l-[ring-(2)H(5)]-phenylalanine and l-[ring-3,5–(2)H(2)]-tyrosine, after which they ingested either 30 g intrinsically l-[1–(13)C]-phenylalanine–labeled milk protein or an equivalent amount of free amino acids labeled with l-[1–(13)C]-phenylalanine. Blood samples and muscle biopsies were obtained to assess protein digestion and amino acid absorption kinetics (secondary outcome), whole-body protein net balance (secondary outcome), and mixed muscle protein synthesis rates (primary outcome) throughout the 6-h postprandial period. RESULTS: Postprandial plasma amino acid concentrations increased after ingestion of intact milk protein and free amino acids (both P < 0.001), with a greater increase following ingestion of the free amino acids than following ingestion of intact milk protein (P-time × treatment < 0.001). Exogenous phenylalanine release into plasma, assessed over the 6-h postprandial period, was greater with free amino acid ingestion (76 ± 9%) than with milk protein treatment (59 ± 10%; P < 0.001). Ingestion of free amino acids and intact milk protein increased mixed muscle protein synthesis rates (P-time < 0.001), with no differences between treatments (from 0.037 ± 0.015%/h to 0.053 ± 0.014%/h and 0.039 ± 0.016%/h to 0.051 ± 0.010%/h, respectively; P-time × treatment = 0.629). CONCLUSIONS: Ingestion of a bolus of free amino acids leads to more rapid amino acid absorption and greater postprandial plasma amino acid availability than ingestion of an equivalent amount of intact milk protein. Ingestion of free amino acids may be preferred over ingestion of intact protein in conditions where protein digestion and amino acid absorption are compromised. Oxford University Press 2021-10-12 /pmc/articles/PMC8754581/ /pubmed/34642762 http://dx.doi.org/10.1093/jn/nxab305 Text en © The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition. https://creativecommons.org/licenses/by/4.0/This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Nuclear Techniques in Nutrition Research Weijzen, Michelle E G van Gassel, Rob J J Kouw, Imre W K Trommelen, Jorn Gorissen, Stefan H M van Kranenburg, Janneau Goessens, Joy P B van de Poll, Marcel C G Verdijk, Lex B van Loon, Luc J C Ingestion of Free Amino Acids Compared with an Equivalent Amount of Intact Protein Results in More Rapid Amino Acid Absorption and Greater Postprandial Plasma Amino Acid Availability Without Affecting Muscle Protein Synthesis Rates in Young Adults in a Double-Blind Randomized Trial |
title | Ingestion of Free Amino Acids Compared with an Equivalent Amount of Intact Protein Results in More Rapid Amino Acid Absorption and Greater Postprandial Plasma Amino Acid Availability Without Affecting Muscle Protein Synthesis Rates in Young Adults in a Double-Blind Randomized Trial |
title_full | Ingestion of Free Amino Acids Compared with an Equivalent Amount of Intact Protein Results in More Rapid Amino Acid Absorption and Greater Postprandial Plasma Amino Acid Availability Without Affecting Muscle Protein Synthesis Rates in Young Adults in a Double-Blind Randomized Trial |
title_fullStr | Ingestion of Free Amino Acids Compared with an Equivalent Amount of Intact Protein Results in More Rapid Amino Acid Absorption and Greater Postprandial Plasma Amino Acid Availability Without Affecting Muscle Protein Synthesis Rates in Young Adults in a Double-Blind Randomized Trial |
title_full_unstemmed | Ingestion of Free Amino Acids Compared with an Equivalent Amount of Intact Protein Results in More Rapid Amino Acid Absorption and Greater Postprandial Plasma Amino Acid Availability Without Affecting Muscle Protein Synthesis Rates in Young Adults in a Double-Blind Randomized Trial |
title_short | Ingestion of Free Amino Acids Compared with an Equivalent Amount of Intact Protein Results in More Rapid Amino Acid Absorption and Greater Postprandial Plasma Amino Acid Availability Without Affecting Muscle Protein Synthesis Rates in Young Adults in a Double-Blind Randomized Trial |
title_sort | ingestion of free amino acids compared with an equivalent amount of intact protein results in more rapid amino acid absorption and greater postprandial plasma amino acid availability without affecting muscle protein synthesis rates in young adults in a double-blind randomized trial |
topic | Nuclear Techniques in Nutrition Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8754581/ https://www.ncbi.nlm.nih.gov/pubmed/34642762 http://dx.doi.org/10.1093/jn/nxab305 |
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