A Moderate Serving of High-Quality Protein Maximally Stimulates Skeletal Muscle Protein Synthesis in Young and Elderly Subjects

T. Brock Symons, Melinda Sheffield-Moore, Robert R. Wolfe, Douglas Paddon-Jones

Research output: Contribution to journalArticle

194 Scopus citations

Abstract

Ingestion of sufficient dietary protein is a fundamental prerequisite for muscle protein synthesis and maintenance of muscle mass and function. Elderly people are often at increased risk for protein-energy malnutrition, sarcopenia, and a diminished quality of life. This study sought to compare changes in muscle protein synthesis and anabolic efficiency in response to a single moderate serving (113 g; 220 kcal; 30 g protein) or large serving (340 g; 660 kcal; 90 g protein) of 90% lean beef. Venous blood and vastus lateralis muscle biopsy samples were obtained during a primed, constant infusion (0.08 μmol/kg/min) of L-[ring-13C6] phenylalanine in healthy young (n=17; 34±3 years) and elderly (n=17; 68±2 years) individuals. Mixed muscle fractional synthesis rate was calculated during a 3-hour postabsorptive period and for 5 hours after meal ingestion. Data were analyzed using a two-way repeated measures analysis of variance with Tukey's pairwise comparisons. A 113-g serving of lean beef increased muscle protein synthesis by approximately 50% in both young and older volunteers. Despite a threefold increase in protein and energy content, there was no further increase in protein synthesis after ingestion of 340 g lean beef in either age group. Ingestion of more than 30 g protein in a single meal does not further enhance the stimulation of muscle protein synthesis in young and elderly.

Original languageEnglish (US)
Pages (from-to)1582-1586
Number of pages5
JournalJournal of the American Dietetic Association
Volume109
Issue number9
DOIs
StatePublished - Sep 1 2009

ASJC Scopus subject areas

  • Food Science
  • Nutrition and Dietetics

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