Effects of Plant- vs Animal-Based Proteins on Muscle Protein Synthesis: A Systematic Review With Meta-Analysis.
Level 1 - systematic review of randomized trials
Systematic review with meta-analysis of human trials
PubMed 42055214 · doi:10.1016/j.jand.2026.156365
What was done
Authors conducted a systematic review and Bayesian 3-level hierarchical random-effects meta-analysis of trials found across major electronic databases (PubMed, Scopus, Cochrane, Sport Discus, Web of Science) up to October 2024. The review compared muscle protein synthesis (MPS) responses to plant- versus animal-based proteins in healthy adults aged 18 to 85 years, with subgroup analyses by age bracket (18–54, 55–64, and 65–85 years), postingestion time points (2, 4, 6, and 24 hours), and resistance exercise conditions.
What was found
Twelve studies met inclusion criteria. Across all participants, MPS slightly favored animal-based proteins with credible intervals spanning null (effect size [ES] Plant:Animal = 0.004, 95% credible interval [CrI] -0.002 to 0.011). In subgroup analyses, adults aged 65 and older showed a modest advantage for animal proteins (ES = 0.013, 95% CrI 0.000 to 0.027), while younger adults showed similar MPS between sources. No substantial differences were seen across postingestion time points or resistance exercise conditions.
Why it matters
This paper clarifies that while plant and animal proteins stimulate similar acute muscle protein synthesis in younger individuals, animal proteins may offer a small anabolic advantage in older adults.
Limits
The total evidence base was small (12 studies) with substantial imprecision in pooled estimates. Animal proteins were mostly milk-derived, whereas plant sources were heterogeneous, limiting broader generalization. Data were also limited across specific postingestion time points and exercise conditions.
Cited by
- supports Brad Schoenfeld has published over 300 studies in the field of exercise and sports nutrition.