Omega-3 Fatty Acids (EPA / DHA)

What they are

The marine long-chain n-3 polyunsaturated fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Found in fatty fish and (in small amounts) made endogenously from plant-source ALA (alpha-linolenic acid).

What the evidence shows

• High-dose icosapent ethyl (4 g/day, pure EPA) reduced major cardiovascular events in patients with elevated triglycerides on statin therapy (REDUCE-IT, 2018).
• Mixed EPA/DHA at low doses in general primary prevention has unconvincing cardiovascular benefit (VITAL, ASCEND, STRENGTH).
• Cognition: DHA is enriched in brain phospholipids; supplementation benefit on cognitive decline is small and inconsistent.
• Mood: modest benefit in major depression in some meta-analyses, particularly EPA-dominant formulations.
• Triglycerides: 2–4 g/day reliably lowers triglycerides.

Dietary vs supplement

Eating fatty fish (salmon, sardines, mackerel) 2–3 times per week is the standard recommendation. For most adults, this is preferable to capsule supplementation. Capsule quality, oxidation, and accurate labelling vary widely.

Safety

• Generally well tolerated.
• Mild bleeding-time increase at very high doses.
• Atrial fibrillation signal at high doses in some recent meta-analyses; weigh against benefit.

Related entries

Mediterranean diet, REDUCE-IT trial, Cardiovascular disease.