The effects of omega-3 polyunsaturated fatty acids on muscle and whole-body protein synthesis: a systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 38777807 · doi:10.1093/nutrit/nuae055
What was done
Authors searched PubMed, Web of Science, Cochrane Library, and Scopus through December 2022 for randomized controlled trials evaluating the effect of omega-3 polyunsaturated fatty acid (n-3 PUFA) ingestion versus control or placebo on muscle protein synthesis (MPS) and whole-body protein synthesis in healthy adults and clinical populations. Eight trials met inclusion criteria. Standardized mean differences (SMDs) with 95% confidence intervals were pooled using a random-effects inverse-variance model, and risk of bias was assessed via the Cochrane RoB 2 tool.
What was found
n-3 PUFA supplementation had no significant effect on MPS rates (k = 6; SMD: 0.03; 95% CI, -0.35 to 0.40; I2 = 30%; P = .89). Subgroup analyses across age, dose, duration, and fractional synthetic rate measurement methods also demonstrated no effect. In contrast, n-3 PUFA ingestion significantly increased whole-body protein synthesis rates (k = 3; SMD: 0.51; 95% CI, 0.12 to 0.90; I2 = 0%; P = .01).
Why it matters
These results clarify that omega-3 supplementation promotes systemic, whole-body protein synthesis rather than direct stimulation of skeletal muscle protein synthesis. Hypothesized benefits of omega-3s on muscle mass may operate through pathways other than basal muscle protein synthesis.
Limits
The total study count is very small (8 studies total, with only 3 studies evaluating whole-body synthesis), and participant sample sizes are not reported in the abstract. Combining healthy and clinical populations introduces clinical heterogeneity, and unmeasured differences in baseline protein intake or physical activity may have confounded outcomes.
Cited by
- context Acute studies demonstrate that omega-3 fatty acid intake has beneficial effects on muscle development, particularly in older adults.