Omega-3 supplementation shows no clear benefit for fat-free mass or muscle strength in healthy adults: a systematic review and meta-analysis of randomized controlled trials.

Omega-3 fatty acids (n-3 FAs) are polyunsaturated FAs incorporated into cell-membrane phospholipids and have been proposed to exert anabolic and anti-inflammatory effects. This systematic review and meta-analysis investigated the effects of n-3 FAs supplementation on fat-free mass (FFM) and muscle strength in healthy adults without obesity. PubMed, Embase, CINAHL, and Web of Science were searched from inception to 25 February 2026. Randomized placebo-controlled trials of isolated n-3 FAs supplementation were eligible. Study selection was conducted using Rayyan; data were extracted in Microsoft Excel; risk of bias was assessed with the Cochrane RoB 2 tool, and certainty of evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation. Standardized mean differences (SMDs) were calculated from postintervention means and pooled postintervention standard deviations. Four studies were included in the meta-analysis for FFM and eight studies in the meta-analysis for muscle strength. For FFM, a conventional random-effects model showed no clear evidence of an effect of n-3 FAs supplementation compared with placebo (SMD 0.26, 95% confidence interval -1.14 to 1.66; P = 0.60). For muscle strength, a three-level random-effects model including 22 dependent effects also showed no clear evidence of an effect (SMD -0.02, 95% confidence interval -0.38 to 0.34; P = 0.92). The certainty of evidence was very low. Current evidence is insufficient to conclude that n-3 FAs supplementation improves FFM or muscle strength in healthy adults.