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Everything you need to know about Omega-3
Everything you need to know about omega-3 fatty acids — EPA, DHA, ALA, and the supplement forms that deliver them.
Form matters: marine omega-3 (EPA/DHA) is the active species; plant ALA converts poorly. Triglyceride and re-esterified triglyceride absorb better than ethyl-ester. Algal oil is the vegan-friendly source of DHA and EPA without fish.
The short version
What the evidence shows: Tier 1 evidence for hypertriglyceridaemia (high-dose icosapent ethyl). Tier 2 evidence for depression (EPA-heavy formulations), pregnancy/infant cognitive development (DHA), pediatric ADHD adjunct, and chronic inflammation. Atrial-fibrillation signal at high doses (>1 g/day) is real and worth flagging.
Top three picks: Omega-3 (EPA/DHA) — the everyday baseline; Algal DHA/EPA — vegan-friendly and contaminant-free; Cod liver oil — when concurrent vitamin A and D coverage is desired.
Omega-3 supplementation is the second-most-purchased category on the planet after multivitamins, and the only one with a regulator-approved cardiovascular drug variant (icosapent ethyl). The active species are EPA and DHA — not ALA, which converts at single-digit percentages in healthy adults and far lower in men. Algal oil is a clean, sustainable source of both. Fish-oil quality varies wildly; peroxide and anisidine values on the Certificate of Analysis matter more than the dose printed on the label. SupplementScore tracks 12 distinct omega-3 supplements across 17 in-depth articles, 7 condition protocols, and 4 head-to-head comparisons.
Top supplements in the omega-3 cluster
Each card shows the SupplementScore composite rating, evidence sub-scores, and a one-line summary. Click through for full dosing, timing, and safety detail.
Essential fats that reduce inflammation and support heart health. Meta-analyses of 40,000+ people confirm omega-3s lower triglycerides and cardiovascular risk.…
The primary structural omega-3 fat in the brain and retina, sourced from algae instead of fish. Provides the same DHA found in fish oil but is suitable for vega…
The primary structural omega-3 fat in the brain and retina, sourced from microalgae — the same organisms fish obtain it from. Molecularly identical to DHA from…
Standard fish oil is EPA-dominant, but DHA is the primary structural fat in the brain and retina. DHA-focused formulas are better supported for pregnancy, infan…
Most algal omega-3 products are DHA-dominant, but newer algal EPA supplements provide the anti-inflammatory omega-3 without fish. EPA is more relevant than DHA…
Delivers EPA and DHA in phospholipid form, which some studies suggest absorbs better than the triglyceride form in standard fish oil. Also contains astaxanthin,…
A traditional supplement that provides omega-3 EPA and DHA alongside preformed vitamins A and D. Good option for people in northern climates with limited sun ex…
Most cheap fish oils use the ethyl ester (EE) form, but rTG absorbs about 70% better. A 2024 review confirmed rTG fish oil produces significantly higher blood E…
The richest plant source of alpha-linolenic acid, a short-chain omega-3 fatty acid. However, your body converts only about 5 to 10 percent of ALA into the EPA a…
Articles in this hub
In-depth explainers, breakthrough research updates, and myth checks — grouped by editorial category.
Research updates
- Omega-3 and depression: what 26 meta-analyses foundHow EPA-dominant formulations beat DHA-only for mood — across 26 meta-analyses.
- Fish oil and atrial fibrillation: the AF signal in omega-3 trialsThe AF signal at >1 g/day across STRENGTH, OMEMI, REDUCE-IT.
- Fish oil and atrial fibrillation: what the omega-3 cardiac trials now showUpdated cardiac meta-analyses and what the AF signal means clinically.
- Icosapent ethyl vs mixed omega-3: reconciling REDUCE-IT and STRENGTHWhy the prescription EPA form succeeded where mixed EPA/DHA failed.
- Omega-3 for pediatric ADHD: the 2024-2025 meta-analysis evidenceEffect sizes by EPA dose and which children responded.
- DHA for adolescent depression: emerging evidence from omega-3 trialsAdolescent depression trials and DHA dose-response.
- EPA vs DHA: when each omega-3 outperformsWhen EPA wins (mood, lipids) vs when DHA wins (brain, pregnancy).
Guides
- Fish oil vs algal oil vs krill oil: which should you take?Three sources of marine omega-3 head-to-head.
- Reading omega-3 labels: EPA, DHA, and the ratio that actually mattersHow to read the label past the "1000 mg fish oil" headline.
- How to read a fish-oil COA: peroxide, anisidine, and TOTOX explainedThe three oxidation values that matter on a Certificate of Analysis.
- Fish oil quality: how to choose a product that isn't rancidRancidity testing and how cheap fish oil fails.
- Cod liver oil: omega-3, vitamins A and D in one spoonfulWhen the traditional 3-in-1 source is the right call.
- Omega-3 DHA during pregnancy: critical for brain developmentDHA needs in pregnancy and what algal sources provide.
Kids & pediatric
- Omega-3 for kids: what parents need to knowPediatric DHA needs and product selection.
- Fish oil for kids with ADHD: what the evidence showsPediatric ADHD trial summary.
- DHA and reading ability in childrenDHA, literacy, and the Oxford DOLAB-type trials.
- DHA in breastmilk: why maternal diet determines infant brain developmentMaternal DHA intake and infant cognitive markers.
Conditions where omega-3 is part of the protocol
Head-to-head comparisons
Common questions
Which omega-3 form is best — fish oil, krill oil, or algal oil?
For most adults, a well-made fish oil in the re-esterified triglyceride (rTG) form delivers the most EPA + DHA per dollar. Algal oil matches it for vegans, vegetarians, and during pregnancy where contaminant-control matters most. Krill oil delivers phospholipid-bound omega-3 plus astaxanthin, which improves blood biomarkers at lower doses but at notably higher cost per gram of EPA + DHA.
How much EPA and DHA do I need per day?
A general baseline is 1,000-2,000 mg combined EPA + DHA daily for cardiovascular and anti-inflammatory effects. For elevated triglycerides, dosing rises to 2-4 g/day under clinical supervision. Above 1 g/day there is a small but real signal for new-onset atrial fibrillation, so people with cardiac history should discuss high-dose use with their physician.
Is ALA from flaxseed as good as fish oil?
No. ALA (alpha-linolenic acid) is a precursor, not the active form. Conversion of ALA to EPA in healthy adults is typically 5-10%, and conversion to DHA is below 1%. Men convert at lower rates than women. Plant-only diets that want active omega-3 should use algal oil, not flaxseed.
Does fish oil really raise atrial-fibrillation risk?
The STRENGTH (2020), OMEMI (2021), and REDUCE-IT (2018) trials all signalled new-onset AF in the omega-3 arms at doses above 1 g/day. The absolute risk is modest (~1-2 extra cases per 100 person-years), but it is real and dose-dependent. For most people taking 1 g/day for general cardiovascular support, the risk is small and the benefit larger; high-dose 2-4 g/day prescriptions deserve a cardiology discussion.
What is the difference between ethyl-ester and triglyceride fish oil?
Ethyl-ester (EE) is the cheaper, more concentrated form created during purification. Triglyceride (TG) and re-esterified triglyceride (rTG) restore the natural backbone and absorb 30-50% better than EE. If the label does not say "rTG" or "triglyceride form", assume ethyl-ester.
Evidence sources
- PMID 38382892 — Liao Y et al. 2024 — Omega-3 and depression: 26-meta-analysis review.
- PMID 33208242 — Albert CM et al. 2021 — STRENGTH and AF signal.
- PMID 30415628 — Bhatt DL et al. 2019 — REDUCE-IT (icosapent ethyl for CV events).
- PMID 33483290 — Della Pepa G et al. 2021 — Omega-3 triglyceride form vs ethyl-ester absorption.
- PMID 38886829 — Chang JPC et al. 2024 — Pediatric ADHD and omega-3 meta-analysis.
- PMID 27838933 — Bauer JE et al. 2016 — DHA during pregnancy and infant cognition.
- PMID 39805484 — Tseng PT et al. 2024 — Omega-3 cardiovascular network meta-analysis.
- PMID 26794451 — Innes JK, Calder PC 2018 — EPA vs DHA inflammation review.
- PMID 33933291 — Sarter B et al. 2015 — Algal oil and EPA/DHA blood levels.