Omega-3 Polyunsaturated Fatty Acid Biomarkers and Risk of Type 2 Diabetes, Cardiovascular Disease, Cancer, and Mortality: A Systematic Review and Meta-analysis

Abstract Background: Considerable attention has focused on omega-3 polyunsaturated fatty acids (PUFA) role in protect against the development of cardiometabolic diseases, which has led to dietary recommendations to increase omega-3 fatty acid intake.Methods: MEDLINE, EMBASE, ISI Web of Science, Cochrane Library, and reference lists were searched for articles from inception to May 2020. Random-effects model was used to estimate the pooled relative risk (RR) and 95% confidence intervals (CIs) for the association of omega-3 PUFAs, including α-linoleic acid (ALA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA), with risk of developing type 2 diabetes (T2D), cardiovascular disease (CVD), including coronary heart disease (CHD) and stroke, cancer, and mortality.Results: 66 prospective studies comprised of 211,600 participants were identified. Individual omega-3 PUFAs showed divergent associations with the study outcomes of interest. An inverse association with risk of T2D was observed comparing extreme categories of ALA concentration (RR,0.91;95%CI,0.83-0.99), but not for the marine-origin omega-3 fatty acids biomarkers. The marine-origin omega-3 fatty acids biomarkers, but not ALA, were significantly associated with lower risks of total CVD, CHD, and overall mortality, with RRs ranging from 0.70 for DHA-CHD association to 0.85 for EPA-CHD association. Lower risk of colorectal cancer was observed at higher levels of DPA (RR,0.76;95%CI:0.59-0.98) and DHA (RR,0.80;95%CI:0.65-0.99). In dose-response analyses, inverse linear associations were observed between EPA, DPA, and DHA biomarkers and CVD or CHD risk, except for DHA-CVD association which showed a nonlinearity association.Conclusion: Higher concentrations of marine-derived omega-3 PUFA biomarkers were associated with a significantly reduced risk of total CVD, CHD, certain types of cancer, and total mortality. Levels of ALA were inversely with a lower risk of T2D but not CVD-related outcomes. These data support the dietary recommendations advocating the role of omega-3 PUFAs in maintaining an overall lower risk of developing cardiovascular disease and premature deaths.