Which Protein-Based Dietary Supplements Most Effectively Enhance Fat-Free Mass and Strength Gains in Healthy Adults Undergoing Resistance Training? A Network Meta-Analysis.

Background: Various protein-based dietary supplements are widely used by individuals engaged in strength training to optimize gains in muscle strength and fat-free mass. However, gaps remain in the scientific literature regarding a comprehensive comparison-particularly the effectiveness of different types of supplemented proteins in healthy adults. This systematic review and network meta-analysis aimed to compare the effectiveness of protein-based dietary supplements, combined with strength training, on increasing muscle strength and fat-free mass in healthy adults. Methods: A network meta-analysis was conducted using randomized controlled trials evaluating different protein supplements combined with strength training. The outcomes assessed were muscle strength (primary) and fat-free mass (secondary). The search was performed in PubMed, Scopus, and Embase up to May 2024, with no restrictions on language or publication date. Results: A total of 78 studies were included, comprising 4755 participants across two outcomes and involving 13 types of protein supplements, plus placebo and control groups. Compared to placebo, for strength, collagen was the most effective supplement (SMD = 0.41; 95% CI: 0.09 to 0.73; Conclusion: Collagen and whey protein are the only protein supplements effective in enhancing strength training effects. Moreover, collagen shows a superior effect compared to whey protein for both outcomes.