Omega-3 (EPA/DHA)

triglyceride · ethyl ester · icosapent ethyl (prescription)

Long-chain marine fatty acids with one of the largest and most contested trial records in the field. The honest summary is three different answers to three different questions — which is exactly what per-claim grading is for.

last reviewed 2026-08-30

by draft — unverified

GRADE

CLAIM

SPECIES

EFFECT

STUDIES

triglyceride lowering — grade A, large effect (human-rct)

Skulas-Ray et al. (AHA advisory) (2019)

species humandesign review of RCTsn 4000duration mixeddose 2–4 g EPA+DHA/dayfunding publicoutcome fasting triglycerides

20–30% reduction at prescription doses, replicated for decades. Grade A — but note the flag: triglycerides are a biomarker, not an outcome you feel.

cardiovascular events — grade B, small effect (human-rct)

Bhatt et al. (REDUCE-IT) (2019)

species humandesign RCT, double-blindn 8179duration 4.9 years mediandose 4 g/day icosapent ethylfunding industryregistry NCT01492361outcome major adverse cardiovascular events

25% relative risk reduction in high-risk statin-treated patients — the strongest positive card. Industry-funded, mineral-oil placebo debated.

Nicholls et al. (STRENGTH) (2020)

species humandesign RCT, double-blindn 13078duration 3.5 years mediandose 4 g/day EPA+DHA carboxylic acidfunding industryregistry NCT02104817outcome major adverse cardiovascular events

No benefit with a corn-oil placebo — the direct contradiction that keeps this claim at B instead of A.

ASCEND Study Group (2018)

species humandesign RCT, double-blindn 15480duration 7.4 yearsdose 840 mg/day EPA+DHAfunding mixedregistry NCT00135226outcome serious vascular events, diabetics without CVD

Supplement-dose omega-3 did nothing for primary prevention. Dose and population matter enormously for this claim.

depression, as adjunct treatment — grade C, small effect (human-rct)

Appleton et al. (Cochrane) (2021)

species humandesign Cochrane review of 35 RCTsn 1924duration mixeddose mixed, mostly EPA-heavyfunding publicoutcome depressive symptom scales

Small-to-modest benefit over placebo with low-certainty evidence and publication-bias concerns.

preventing cognitive decline in healthy older adults — grade E, negligible effect (human-rct)

Sydenham et al. (Cochrane) (2012)

species humandesign Cochrane review of 3 RCTsn 3536duration 6–40 monthsdose mixedfunding publicoutcome cognitive test batteries

No effect on cognition in cognitively healthy older adults. Tested properly, found not to work — that's what grade E means.

Grade timeline

2025-12

cardiovascular events: B → B

Re-reviewed after new icosapent-ethyl subgroup analyses; the REDUCE-IT/STRENGTH contradiction still caps this at B. Kept under review.

Dosing & safety

TYPICAL SUPPLEMENT DOSE500–1000 mg EPA+DHA/day

DOSES USED IN STUDIES840 mg – 4 g EPA+DHA/day in outcome trials

UPPER LIMIT~5 g/day EPA+DHA from supplements (EFSA: no safety concern up to this)

SAFETY NOTE High doses increase bleeding tendency and, in the 4 g icosapent ethyl trials, atrial fibrillation risk. Talk to your doctor if you take anticoagulants.

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