Does chronic polyphenol supplementation modify resistance training-induced strength and muscle morphology adaptations in adults? A systematic review and multilevel meta-analysis of randomized controlled trials
Study Details
This systematic review and multilevel meta-analysis included 11 randomised trials and 360 adults, examining whether chronic polyphenol supplementation altered strength and muscle adaptations to resistance training 🔍
Supplements included curcumin, quercetin, catechins, matcha, epicatechin, berry polyphenols, green tea and soy isoflavones 🫐
Polyphenols are often used to support recovery because of their anti-inflammatory and antioxidant properties 🔋
This creates a theoretical concern that repeatedly suppressing exercise-induced inflammation or oxidative stress could blunt signalling involved in adaptation ⚠️
Here are the key findings ⬇️
Key Findings
🏋️ Reassuringly, the review found no consistent evidence that polyphenol supplementation impaired resistance-training adaptations
💪 Strength actually showed a small positive effect, although this narrowly missed statistical significance
⚖️ However, certainty of evidence for strength was rated low
📈 Muscle quantity/lean mass showed a small, non-significant effect
🧬 Direct measures of muscle morphology, including muscle thickness and cross-sectional area, were essentially unchanged
↔️ Importantly, there was therefore no clear signal that chronic polyphenol use attenuated muscle growth
📊 Results remained similar across sensitivity analyses, with no robust differences according to age, intervention duration, strength-test type or broad polyphenol class
Conclusion
Polyphenols may improve soreness, inflammation, oxidative stress or short-term recovery in some contexts, but these recovery effects did not appear to come at the expense of long-term training adaptation 💪
Evidence remains limited, particularly for direct muscle morphology, so an interference effect cannot be completely ruled out ⚠️
However, for athletes using polyphenol-rich foods or supplements to support recovery, these findings are reassuring: current evidence suggests they are unlikely to blunt strength or hypertrophy adaptations to resistance training, although they also do not appear to meaningfully enhance them ✅
Reference
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2026.1906384/full
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