Omega-3 polyunsaturated fatty acids linked to lower mortality from coronary heart disease

1. Biomarkers for omega-3 polyunsaturated fatty acid (omega-3 PUFA) levels were linked to lower mortality from coronary heart disease (CHD) in patients without prior known history of CHD.

2. Higher levels of docosapentaenoic acid (DPA), an omega-3 PUFA, was associated with lower risk of total CHD, but other markers, including eicosapentaenoic acid (EPA), docosahexaneoic acid (DHA), and a-linolenic acid (ALA), had no observable effect on total CHD risk.

Evidence Rating Level: 2 (Good)

Study Rundown: The role of diet-derived omega-3 PUFA in protection from morbidity and mortality associated with cardiovascular disease remains controversial. While some experimental studies have reported protective effects, randomized trials of fish oil supplements in those with CHD have failed to demonstrate significant effect. This study sought to evaluate the association between biomarkers representative of seafood- and plant-derived omega-3 PUFA and the risk of CHD in patients without prior history of significant CHD.

This global consortium of 19 studies evaluated the following omega-3 PUFA markers: eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaneoic acid (DHA), and a-linolenic acid (ALA). Analysis was controlled for confounders such as age, sex, race, diabetes, and medications (including statins and aspirin). ALA, DPA, and DHA were associated with lower risk of fatal CHD, and DPA was associated with lower risk of total CHD. No observed effect on nonfatal MI was observed. The strengths of the study included the pooled data across many geographic locations and racial backgrounds. The utilization of biomarkers for ω-3 PUFA helped to accurately capture stable feeding habits, but they may have merely been markers of general healthy eating and not directly responsible for the improved outcomes.

Click to read the study, published today in JAMA Internal Medicine

Relevant Reading: Association Between Omega-3 Fatty Acid Supplementation and Risk of Major Cardiovascular Disease Events

In-Depth [meta-analysis]: This study included 19 studies from a global consortium investigating dietary omega-3 PUFA through the use of biomarkers. There were 16 countries involved and 45 637 total participants without prior CHD. Biomarkers included EPA, DPA, DHA, and ALA from plasma, plasma phospholipid, cholesterol esters, or adipose tissue. CHD included fatal or non-fatal MI, sudden cardiac death, with total CHD and fatal CHD included in analysis. Covariates evaluated included age, sex, race, body mass index, educational level, smoking status, physical activity, alcohol use, diabetes mellitus, hypertension, aspirin use, and hypercholesterolemia.

In continuous variable analysis (per 1-SD increase) there was a ~9% lower risk of fatal CHD for each ω-3 PUFA with the relative risk for EPA of 0.91 (95%CI 0.82-1.00), DPA 0.90 (95%CI 0.85-0.96), DHA 0.90 (95%CI 0.84-0.96), and ALA 0.91 (95%CI 0.84-0.98). DPA levels were associated with lower risk of total CHD with relative risk 0.94 (95%CI 0.90-0.99). None of the biomarker levels were associated with changes in non-fatal MI risk.

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