Fish consumption and CHD mortality: an updated meta-analysis of seventeen cohort studies

Omega-3 fatty acids and coronary heart disease. The final verdict?

PURPOSE OF REVIEW

The fish fatty acids eicosapentenoic acid (EPA) and docosahexenoic acid (DHA) may be protective against fatal coronary heart disease (CHD) and sudden cardiac death. This review summarizes the recent findings of prospective cohort studies and randomized controlled trials.

RECENT FINDINGS

A recently published meta-analysis of 17 prospective cohort studies showed that eating fish once a week compared to eating less fish was associated with a 16% lower risk of fatal CHD. Epidemiologic studies with cardiac arrest or sudden cardiac death as endpoint observed also an inverse relation with fish consumption. In contrast, a recently published meta-analysis of 14 randomized, double-blind, placebo-controlled trials in cardiovascular patients did not show a protective effect of an additional amount of EPA-DHA on fatal CHD and sudden cardiac death. Subgroup analyses suggested that this could be because of a low absolute risk as a consequence of the state-of-the-art drug treatment.

SUMMARY

Eating fatty fish once or lean fish twice a week is recommended for both primary and secondary prevention of CHD. A definite statement cannot be made about the dosage of EPA-DHA required for secondary prevention of CHD.

Marine N-3 polyunsaturated fatty acids are inversely associated with risk of type 2 diabetes in Asians: a systematic review and meta-analysis

BACKGROUND

Prospective cohort studies in relation to the associations between n-3 polyunsaturated fatty acids (PUFA) and risk of type 2 diabetes (T2D) were inconsistent. Differences in tissue n-3 PUFA compositions in subjects with and without T2D were also inconsistent in both cohort and case-control studies. We conducted a systematic review and meta-analysis of prospective cohort studies to examine the associations of fish and n-3 PUFA intake with T2D risk. The differences in tissue n-3 PUFA compositions in subjects with and without T2D were investigated based on cohort and case-control studies.

METHODS AND FINDINGS

PubMed, Embase, Cochrane library, China National Knowledge Infrastructure (CNKI) and Chinese VIP database up to January 2012 was used to identify relevant studies, and reference lists from retrieved studies were reviewed. Two authors independently extracted the data. Random-effects models were used to pool the summary relative risk (RR). Twenty-four studies including 24,509 T2D patients and 545,275 participants were identified. For cohort studies, the summary RR of T2D for the highest vs lowest categories of total fish, marine n-3 PUFA and alpha-linolenic acid intake was 1.07 (95% CI: 0.91, 1.25), 1.07 (95% CI: 0.95, 1.20) and 0.93 (95% CI: 0.81, 1.07), respectively. Subgroup analyses indicated that summary RR (highest vs lowest category) of T2D for fish and marine n-3 PUFA intake was 0.89 (95% CI: 0.81, 0.98) and 0.87 (95% CI: 0.79, 0.96) for Asian populations, and 1.20 (95% CI: 1.01, 1.44) and 1.16 (95% CI: 1.04, 1.28) for Western populations. Asian subjects with T2D had significantly lower tissue compositions of C22:6n-3 (SMD: -1.43; 95% CI: -1.75, -1.12) and total n-3 PUFA (SMD: -1.41; 95% CI: -2.23, -0.59) compared with those without T2D.

CONCLUSION

This systematic review and meta-analysis provides evidence that marine n-3 PUFA have beneficial effects on the prevention of T2D in Asian populations.