The Effect of Long-Chain Omega-3 Polyunsaturated Fatty Acid Supplementation on Neuromuscular Function in Humans: A Systematic Review with Narrative Synthesis

CONTEXT: Neuromuscular function is central to strength, movement control, and fatigue resistance, with relevance for athletic performance and healthy ageing. Long-chain n-3 polyunsaturated fatty acid (LCn-3 PUFA) supplementation has been reported to improve muscle strength and physical function in the absence of muscle hypertrophy, suggesting modulation of neuromuscular function; however, the extent, consistency, and underlying mechanisms of these effects remain unclear. OBJECTIVE: The objective of this study was to systematically review the effects of LCn-3 PUFA supplementation on neuromuscular function across the lifespan in humans. DATA SOURCES: This systematic review with narrative synthesis was conducted in accordance with PRISMA 2020 guidelines. Literature searches were performed in PubMed, Web of Science, SPORTDiscus, and Scopus. DATA EXTRACTION: Eligibility criteria were defined using the participants, intervention, comparator, outcomes, and study design (PICOS) framework. Randomized and nonrandomized controlled trials in humans examining orally administered LCn-3 PUFA supplementation and neuromuscular outcomes were eligible for inclusion. Outcomes were classified as neural, muscular, or global indicators of neuromuscular function, and the findings synthesized in a narrative format. DATA ANALYSIS: Eleven studies were included. A range of neuromuscular outcomes were assessed across neural, muscular, and global domains, with substantial heterogeneity in the outcome measures, supplementation protocols, and study contexts. LCn-3 PUFA supplementation was associated with improvements in some neuromuscular outcomes; however, the findings were inconsistent, with numerous null and occasional context-specific adverse effects being reported. The limited evidence suggests that effects may be more likely following LCn-3 PUFA supplementation for around 2 weeks or longer, and that docosahexaenoic acid may play a role in neural outcomes, while interactions with structured exercise training remain unclear. CONCLUSION: LCn-3 PUFA supplementation may influence aspects of neuromuscular function; however, the current evidence is limited and heterogeneous. Further well-controlled studies using standardized supplementation protocols and neuromuscular assessments are required in order to clarify potential mechanisms and identify populations most likely to benefit.