Effects of Plant- vs Animal-Based Proteins on Muscle Protein Synthesis: A Systematic Review With Meta-Analysis

Area of Science:

• Nutritional Science
• Exercise Physiology
• Gerontology

Background:

• Growing interest in plant-based diets for health, ethical, and environmental reasons.
• Need to compare muscle protein synthesis (MPS) efficacy between plant and animal proteins.
• Investigating age- and time-dependent effects on MPS response.

Purpose of the Study:

• Systematic review and meta-analysis comparing MPS response to plant vs. animal proteins.
• Stratifying MPS response by age groups (18-85 years) and post-ingestion times (2-24 hours).
• Examining the role of resistance exercise in modulating MPS differences.

Main Methods:

• Searched major databases (PubMed, Scopus, etc.) for relevant studies up to October 2024.
• Assessed risk of bias using GRADE.
• Employed Bayesian three-level hierarchical random effects models with subgroup analyses.

Main Results:

• Overall, a slight favor for animal-based proteins (ES=0.004), with small differences and uncertainty.
• Older adults (≥65 years) showed a modest advantage for animal proteins (ES=0.013).
• No significant differences observed across post-ingestion times or with resistance exercise.

Conclusions:

• Point estimates suggest animal proteins may be slightly superior, particularly for older adults.
• Limited study numbers and imprecision restrict definitive conclusions.
• Further high-quality trials are required to ascertain plant-based proteins' anabolic potential.