Omega-3 fatty acids showed greater efficacy in trials judged of lower quality (JADAD=3 or 4) than in trials judged of higher quality (JADAD=5; Test for subgroup differences: Chi2 = 7.2, df = 1 (P = 0.007), I2 = 86%). The effect size for omega-3 fatty acids in lower quality trials was 0.47 (95% CI: 0.17 0.76) compared to 0 (95% CI: -0.17, 0.17) in higher quality trials (see Figure 5). Lower quality trials as rated by the JADAD scale generally provided insufficient evidence about the appropriateness of randomization or blinding techniques (or both).