Journal Article


Lorraine Brennan
Elaine Hillesheim
Janine Wirth


Physiotherapy & Sport

muscle strength adults muscle synthesis obesity protein timing of intake lean body mass elderly body composition

The Role of Protein Intake and its Timing on Body Composition and Muscle Function in Healthy Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials (2020)

Abstract Background Increased protein intake has been suggested to improve gains in muscle mass and strength in adults. Furthermore, the timing of protein intake has been discussed as a margin of opportunity for improved prevention measures.Objective This systematic review investigated the effect of protein supplementation on body composition and muscle function (strength and synthesis) in healthy adults, with an emphasis on the timing of protein intake.Methods Randomized controlled trials were identified using PubMed, Web of Science, CINAHL, and Embase, up to March 2019. For meta-analyses, data on lean body mass (LBM), handgrip strength, and leg press strength were pooled by age group (mean age 18–55 or >55 y) and timing of protein intake. The quality of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluations approach.Results Data from 65 studies with 2907 participants (1514 men and 1380 women, 13 unknown sex) were included in the review. Twenty-six, 8, and 24 studies were used for meta-analysis on LBM, handgrip strength, and leg press strength, respectively. The protein supplementation was effective in improving (mean difference; 95% CI) LBM in adults (0.62 kg; 0.36, 0.88) and older adults (0.46 kg; 0.23, 0.70), but not handgrip strength (older adults: 0.26 kg; -0.51, 1.04) and leg press strength (adults: 5.80 kg; -0.33, 11.93; older adults: 1.97 kg; -2.78, 6.72). Sensitivity analyses removing studies without exercise training had no impact on the outcomes. Data regarding muscle synthesis were scarce and inconclusive. Subgroup analyses showed no beneficial effect of a specific timing of protein intake on LBM, handgrip strength, and leg press strength.Conclusion Overall, the results support the positive impact of protein supplementation on LBM of adults and older adults, independently of intake timing. Effects on muscle strength and synthesis are less clear and need further investigation. This systematic review was registered on PROSPERO as CRD42019126742.
Collections Ireland -> University College Dublin -> School of Agriculture and Food Science
Ireland -> University College Dublin -> Conway Institute Research Collection
Ireland -> University College Dublin -> Agriculture and Food Science Research Collection
Ireland -> University College Dublin -> Institute of Food and Health
Ireland -> University College Dublin -> College of Health and Agricultural Sciences
Ireland -> University College Dublin -> Institute of Food and Health Research Collection
Ireland -> University College Dublin -> Conway Institute
Ireland -> University College Dublin -> Institutes and Centres

Full list of authors on original publication

Lorraine Brennan, Elaine Hillesheim, Janine Wirth

Experts in our system

Lorraine Brennan
University College Dublin
Total Publications: 166