The limited effect of omega-3 polyunsaturated fatty acids on cardiovascular risk in patients with impaired glucose metabolism: a meta-analysis.

OBJECTIVES The impacts of marine-derived n-3 polyunsaturated fatty acids (n-3 PUFAs) on cardiovascular risk are not well known. We conducted this meta-analysis to determine the effects of n-3 PUFAs on cardiovascular outcomes and cardiovascular risk markers in patients with impaired glucose metabolism (IGM). DESIGN AND METHODS We searched PUBMED, EMBASE, The Cochrane Library and reference lists of relevant papers for high quality randomized controlled trials comparing dietary intake of n-3 PUFAs with placebo in IGM patients. Data was extracted and quality assessed independently by two reviewers. Authors were contacted for missing information. Overall estimates were calculated using a random-effects model or a fixed-effects model, and the possibility of publication bias was examined using a funnel plot. Subgroup analyses were conducted to explore the association between the risk markers and study characteristics. RESULTS Our meta-analysis included 19 studies, 24,788 patients. Compared with placebo, n-3 PUFAs had no statistically significant reduce effect on cardiovascular mortality, major cardiovascular events, all-cause mortality or composite endpoint of all-cause mortality or hospitalization for cardiovascular cause, however it can significantly reduce the level of triglycerides (weighted mean difference [WMD] -0.25mmol/L; 95% CI -0.37 to -0.13: p<0.001; 12 trials, 13,921 patients). CONCLUSION Marine-derived n-3 polyunsaturated fatty acids have no protective effect on cardiovascular mortality, major cardiovascular events, all-cause mortality and composite endpoint of all-cause mortality or hospitalization for cardiovascular cause in IGM patients, but can reduce triglyceride level.