Omega-3 fatty acids

fatty-acidpolyunsaturated

What is it

Omega-3 fatty acids are polyunsaturated fatty acids whose first double bond lies three carbons from the methyl terminus. The principal members are alpha-linolenic acid (ALA, 18:3n-3) from plants and the marine long-chain forms EPA (20:5n-3) and DHA (22:6n-3), which serve as substrates for resolvin/protectin lipid mediators and structural roles in neuronal membranes.

Evidence for 5 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Hypertriglyceridemia

Strong

2-4 g/day of EPA+DHA lower triglycerides 20-30%; pharmaceutical icosapent ethyl (EPA only) reduced major adverse cardiovascular events in REDUCE-IT.

Cardiovascular events (high-risk)

Good

Multiple meta-analyses show modest reductions in CHD death and MI; benefit is most consistent in patients with elevated triglycerides on statin therapy.

Rheumatoid arthritis symptoms

Good

2-4 g/day reduces morning stiffness and tender joint count, allowing NSAID dose reduction in some trials.

Fetal neurodevelopment

Good

200-300 mg/day DHA during pregnancy supports fetal visual and cognitive development; FDA/EPA jointly recommend 2-3 servings of low-mercury fish weekly.

Major depressive disorder (adjunct)

Limited

EPA-predominant formulations (>=60% EPA) at 1-2 g/day show modest antidepressant adjunctive effect in meta-analyses; heterogeneity is high.

Dosage

The AHA recommends 250-500 mg/day of combined EPA+DHA for cardiovascular health from fish or supplements; pharmacologic doses for hypertriglyceridemia are 2-4 g/day (per FDA-approved icosapent ethyl). ALA-only intake (e.g., flaxseed) supplies 1.1-1.6 g/day per the Adequate Intake.

Safety

Doses above 3 g/day combined EPA+DHA may modestly prolong bleeding time and should be coordinated with antiplatelet/anticoagulant therapy. Higher-dose icosapent ethyl trials (REDUCE-IT) showed increased atrial fibrillation; fishy aftertaste/reflux is the most common GI complaint.

References

  • Wikidata: Omega-3 fatty acid — Wikidata link
  • ODS Omega-3 Fact Sheet — NIH ODS link
  • DSLD: Omega-3 Fatty Acids — NIH DSLD link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.