Essential Fatty Acid
Omega-3 (EPA/DHA)
Strong EvidenceLarge randomised trials and meta-analyses support EPA/DHA for cardiovascular endpoints and membrane composition; the cognitive evidence is weaker and largely limited to people with low baseline intake.
Recommended Dose
2 g combined EPA/DHA daily (minimum 1 g EPA)
Timing
Morning with a fatty meal
Mechanism of Action
DHA integrates into neuronal membranes, enhancing fluidity and receptor function. EPA resolves neuroinflammation via SPMs (specialized pro-resolving mediators). Together they support synaptic plasticity.
Side Effects & Safety
Fishy aftertaste, mild GI discomfort. Choose molecularly distilled for purity. The bleeding concern is weaker than its reputation — randomised trials show no increase in clinically significant bleeding — while the better-supported dose risk is atrial fibrillation above 1500 mg/day, and only in people already at high cardiovascular risk. See the safety section.
Do not use / talk to a doctor first
- Existing atrial fibrillation, or high cardiovascular risk, at doses above 1 g/day combined EPA/DHA
- Known allergy to fish, shellfish or the source organism
- Scheduled surgery - many surgical teams ask for supplements affecting platelet function to stop beforehand
Interactions
Warfarin and other vitamin-K antagonists
Fish oil at 3-6 g/day did not significantly change INR or adverse-event rates in a retrospective anticoagulation-clinic cohort. FDA-approved omega-3 package inserts still direct periodic INR monitoring when the two are combined, so treat it as monitoring rather than avoidance
Source: Pryce 2016, Nutrients (PMC5037562); FDA omega-3 prescribing information
Antiplatelet drugs and NSAIDs
Shared effect on bleeding time. A 2024 systematic review and meta-analysis of randomised trials found no increase in clinically significant bleeding, so this is a discuss-with-your-prescriber point, not a contraindication
Source: Javaid 2024, J Am Heart Assoc (PMID 38742535)
High-dose EPA/DHA itself (dose effect, not a drug)
Raised atrial-fibrillation risk in ONE group only: people already at high cardiovascular risk taking more than 1500 mg/day (OR 1.43, 95% CI 1.14-1.79; absolute risk difference 0.8%). The other three groups were not significant, and low-cardiovascular-risk participants on a HIGH dose came out at OR 1.03 - essentially unchanged
Source: Abuknesha 2026, Circ Arrhythm Electrophysiol - 35 trials, n=114,592 (PMID 42517224)
Pregnancy & breastfeeding
EPA and DHA are routinely recommended in pregnancy and DHA is used in prenatal formulas; the concern is contaminant load in the source oil rather than the fatty acids. Choose a tested product and agree the dose with a midwife or doctor.
Who should avoid / see a doctor
This page recommends 2 g combined EPA/DHA, above the 1500 mg/day threshold where the atrial-fibrillation signal appears. That signal was found ONLY in people already at high cardiovascular risk (OR 1.43, absolute difference 0.8%); at low cardiovascular risk a high dose came out at OR 1.03, essentially unchanged. So: if you have established cardiovascular disease, atrial fibrillation or another arrhythmia, agree this dose with your doctor before taking it. If you do not, the trial evidence does not show this dose raising your AF risk.
Synergies
Used in These Stacks
See Omega-3 (EPA/DHA) inside a full protocol — the stack pages cover when and why to combine it.
Best Products
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References
- 1.Abuknesha 2026, Circulation: Arrhythmia and Electrophysiology — Atrial-fibrillation risk rose only in participants at high cardiovascular risk taking over 1500 mg/day EPA+DHA: OR 1.43 (95% CI 1.14-1.79), absolute risk difference 0.8%. The other three dose/risk groups were non-significant (OR 1.07, 1.06 and 1.03), including low-risk participants on a high dose. (meta-analysis, 35 randomised trials, n=114,592)
- 2.Javaid 2024, Journal of the American Heart Association — Omega-3 supplementation did not produce a statistically significant increase in clinically significant bleeding across randomised trials. (systematic review and meta-analysis)
- 3.Pryce 2016, Nutrients — Fish oil taken with warfarin did not significantly affect INR or the incidence of adverse events in patients with atrial fibrillation or deep vein thrombosis. (retrospective cohort)
