BACKGROUND AND PURPOSE: 

• There have been studies in the literature suggesting that omega-3 polyunsaturated fats may be protective against cardiovascular disease although literature is conflicting  
  • Omega-3 fats are ingested in the form of oily fish or fish oil (often fish liver) capsules and can also be plant based  
    • Oily fish: long-chain omega-3 (LCn3), which includes eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)  
    • Plant based: Alpha-linolenic acid (ALA) 
  • There is professional guidance on this subject regarding the consumption of fish and some organizations also recommend supplementation for those with coronary artery disease (e.g., AHA) 
• There may be bias in previous studies, because fish consumption in some regions is associated with a more health-conscientious life style  
• Abdelhamid et al. (The Cochrane Library, 2018) sought to determine the impact of fish- and plant-based omega-3 on all-cause mortality, cardiovascular (CVD) events, adiposity and lipids 
  • Review commissioned by WHO to inform the next set of recommendations on polyunsaturated fatty acid intake in children and adults  

METHODS: 

• Database search of RCTs and meta-analysis 
  • Studies lasting ≥12 months  
  • Intervention: Supplementation and/or advice to increase LCn3 or ALA (>10% of total fat) intake  
  • Control: Usual or lower intake  
• To avoid bias, two independent researchers assessed studies for inclusion, extracted data and assessed validity  
• Primary outcome: Long-chain omega-3 (LCn3, fish-based omega-3 fats) or ALA (plant-based omega-3 fats) fats and risk for 
  • All-cause mortality | Cardiovascular deaths | Cardiovascular events | Coronary heart disease deaths | Coronary heart disease events | Stroke | Arrhythmia | Adiposity and lipids 
• Secondary Outcomes: If omega-3 fatty acids are found to be effective, is protection  
  • Seen in both low and at high risk for cardiovascular disease 
  • Dependent on dose and duration  
  • Different depending if dietary or supplemental 
• GRADE methods used to assess result quality

RESULTS: 

• 79 RCTs were included  
• There was little or no effect of increasing LCn3 on 
  • All-cause mortality | Cardiovascular mortality | Cardiovascular events | CHD mortality | Stroke | Arrhythmia, CHD events 
• Increasing ALA intake made little to no difference for 
  • All-cause mortality | Cardiovascular mortality | CHD events 
• ALA enriched diet did reduce the risk of 
  • Cardiovascular events: Reduction from 4.8% to 4.7% – risk ratio (RR) 0.95; 95% CI, 0.83 to 1.07 (low-quality evidence) 
  • CHD mortality: Reduction from 1.1% to 1.0% – RR 0.95; 95% CI, 0.72 to 1.26 (moderate-quality evidence) 
  • Arrhythmia:Reduction from 3.3% to 2.6% – RR 0.79; 95% CI, 0.57 to 1.10 (moderate-quality evidence) 
  • Evidence for stroke unclear due to low-quality evidence

CONCLUSION: 

• High-quality evidence demonstrated no benefit to EPA or DHA in the prevention of all-cause deaths and cardiovascular events 
• Moderate-quality evidence suggests that there is likely little or no difference for cardiovascular death, coronary deaths or events, stroke, or heart irregularities 
• Foods rich in omega-3 fats (such as walnuts, canola oil or enriched margarine)  
  • Likely makes little difference for all-cause or cardiovascular deaths or coronary events 
  • May protect against slightly reduce cardiovascular events, coronary mortality and heart irregularities

Learn More – Primary Sources: 

Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease

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