By Erin Rose · Updated July 27, 2026 · Reviewed against primary sources · Methodology · About Us Not medical advice — this summarizes published research; talk to a clinician before starting a supplement, especially at high doses. Methodology . For general health, take a balanced EPA+DHA product — no ratio beats another, so do not overthink it. Bias the ratio only for a specific goal: EPA-forward (above 2:1 EPA:DHA , 1-2 g EPA/day ) for mood and depression ; DHA-adequate (at least 200 mg DHA/day ) for pregnancy and infant development . DHA lowers triglycerides slightly more; pure EPA is the one studied in high-risk heart patients. One honest caveat: in already-healthy adults, neither has been shown to sharpen memory or prevent eye disease. As an Amazon Associate we earn from qualifying purchases. Picks are ranked by EPA+DHA per dose, form, and cost, never commissions. The short version: both are essential and most products contain both. EPA is a signaling molecule with the best evidence for depression ; DHA is a structural building block of the brain and retina and matters most in pregnancy . Bias the ratio to your goal (EPA-forward for mood, DHA-adequate for pregnancy/eyes); for general health, a balanced product is fine. Below, what the actual trials show — including where the popular claims don't hold up. What Is the Difference Between EPA and DHA? DHA builds; EPA signals. DHA is a physical component of cell membranes — it's concentrated in the retina, brain gray matter, and sperm, where it keeps membranes fluid and functional. EPA is barely present in those tissues; instead it competes with the omega-6 arachidonic acid at the enzymes that make inflammatory signals, nudging the balance toward less inflammation. Both are also raw material for specialized pro-resolving mediators (resolvins and protectins) that help actively switch off inflammation ( Serhan 2014, PMID: 24899309 ) — real biochemistry, though that's a mechanism, not proof a supplement treats any specific disease. One nuance the label won't tell you: your body converts the plant omega-3 (ALA, from flax and chia) into EPA and DHA very inefficiently — a few percent at best — so pre-formed EPA/DHA from fish or algae is the practical way to raise your levels. And while DHA can spare some EPA (taking DHA slows how fast you burn through EPA), a careful isotope study found DHA is not meaningfully converted backward into new EPA ( Metherel 2019, PMID: 31204771 ). EPA vs DHA: Head to Head Is EPA or DHA Better for Depression and Mood? This is where the ratio genuinely matters. Multiple meta-analyses converge on the same threshold: omega-3 helps depression only when the formula is EPA-dominant . Supplements with at least 60% EPA showed an antidepressant effect; formulas under 60% EPA — including DHA-major ones — did not ( Sublette 2011, PMID: 21939614 ; Liao 2019, PMID: 31383846 ). An international nutritional-psychiatry practice guideline recommends 1–2 g/day of net EPA , from pure EPA or an EPA:DHA ratio above 2:1 ( Guu 2019, PMID: 31480057 ). Two honest caveats: this is studied mostly as an add-on to standard treatment, not a replacement, and the effect is modest — EPA is a reasonable adjunct, not a cure. And most standard fish oils are only about 1:1 to 2:1 EPA:DHA, so hitting a true mood dose usually means a dedicated high-EPA concentrate. Is EPA or DHA Better for Lowering Triglycerides? Both EPA and DHA lower triglycerides, but the one systematic review that compared them head-to-head found DHA lowers triglycerides slightly more than EPA . DHA also raises HDL ("good") cholesterol and tends to raise LDL cholesterol and LDL particle size (larger, more buoyant particles — a mixed signal), whereas EPA — unlike DHA — was not associated with those HDL/LDL changes in the reviewed trials ( Innes & Calder 2018, PMID: 29425187 ). The evidence base is small, so treat the difference as modest. For an actual clinical triglyceride dose, the target is about 4 g/day of combined EPA+DHA under medical supervision — not a casual over-the-counter habit. Is EPA or DHA Better for the Brain, Eyes, and Pregnancy? DHA is unambiguously the structural omega-3 for the developing brain and retina, which is why it's a staple of prenatal nutrition. During pregnancy and infancy, adequate DHA supports brain and eye development ( Rogers 2013, PMID: 23266567 ); international prenatal guidance commonly targets at least 200 mg DHA/day. That developmental case is solid. Where the marketing outruns the evidence. The leap from "DHA builds the brain and eyes" to "a DHA supplement will sharpen your thinking or protect your eyes" is not supported by the best trials in already-healthy adults: Cognition: a Cochrane review found omega-3 supplements did not improve cognition or prevent decline in cognitively healthy older adults ( PMID: 22696350 ). Dry eye: the large DREAM trial found 3,000 mg/day EPA+DHA was no better than placebo ( PMID: 29652551 ). Macular degeneration: AREDS2 found adding omega-3 did not slow progression to advanced AMD ( PMID: 23644932 ). So: prioritize DHA in pregnancy and for a genuinely low intake — but don't buy a DHA supplement expecting a memory or eyesight upgrade. Is EPA or DHA Better for Heart Health? The heart story is often mis-told as "EPA beats DHA." What the trials actually show is a population story. In high-risk patients already on a statin with elevated triglycerides, prescription pure EPA (icosapent ethyl, 4 g/day) cut cardiovascular events — 17.2% vs 22.0%, about a 25% relative reduction ( REDUCE-IT, PMID: 30415628 ). But in broad, lower-risk populations, mixed EPA+DHA was null ( VITAL, PMID: 30415637 ), and a high-dose EPA+DHA trial in high-risk patients was stopped early for futility ( STRENGTH, PMID: 33190147 ). One more asterisk: REDUCE-IT used a mineral-oil placebo , and the placebo group's LDL and inflammatory markers rose — so some researchers argue the EPA "benefit" was partly a placebo harm inflating the gap ( PMID: 34370544 ); the investigators dispute that the oil mattered ( PMID: 33061866 ). Net: for healthy people, fish oil is a reasonable way to top up omega-3, not a proven heart-attack preventive — that benefit is specific to high-risk, high-triglyceride patients under a doctor's care. What EPA to DHA Ratio Should You Take? How to Read EPA and DHA on the Label Whatever ratio you want, read the actual EPA and DHA numbers — not the "fish oil" total. A typical label: Fish Oil: 1,200 mg — total oil weight, mostly irrelevant. EPA: 360 mg + DHA: 240 mg = 600 mg EPA+DHA — this is what actually counts, and it tells you the ratio (here, 1.5:1). To reach a 1,000 mg EPA+DHA target with that product you'd need about two softgels. Always add EPA and DHA yourself, and make sure the form is triglyceride, not ethyl ester . Omega-3 Picks by Goal EPA+DHA per serving is pulled live from our product data, so it matches our full buying guide . For a true mood dose you'll usually want a dedicated high-EPA concentrate (most standard fish oils aren't EPA-forward enough). See the full fish-oil comparison for form, certification, and cost per serving across all the products we track. A Note on Safety High-dose omega-3 has two real cautions. Above about 3 g/day, fish oil has a mild blood-thinning effect — if you take an anticoagulant or antiplatelet medication, have a bleeding disorder, or have surgery coming up, talk to your doctor first. Separately, high-dose omega-3 (≥3-4 g/day) was linked to a higher rate of atrial fibrillation in the REDUCE-IT and STRENGTH trials ( PMID: 30415628 , PMID: 33190147 ), so anyone with a history of AFib or arrhythmia should check with a doctor before high-dose use. The evidence · Omega-3

What the published reviews of Omega-3 concluded Omega-3 fatty acids for depression in adults. · The Cochrane database of systematic reviews , 2021 “At present, we do not have sufficient high-certainty evidence to determine the effects of n-3PUFAs as a treatment for MDD.” “At present, we do not have sufficient high-certainty evidence to determine the effects of n-3PUFAs as a treatment for MDD.” Method: PubMed searched in humans for systematic reviews with Omega-3 in the title; these 1 of the 9 that qualified are shown with the authors’ own conclusion quoted rather than summarised. What it cannot tell you: whether Omega-3 will work for you — each of these reports an average across trials, and null findings are shown here as readily as positive ones. Frequently Asked Questions What is the difference between EPA and DHA? DHA is structural — a building block of brain and retinal membranes. EPA is more of a signaling molecule and has the strongest evidence for depression. Most fish oil has both; the ratio varies. Balanced is fine for general health; bias the ratio for a specific goal. Should I take more EPA or DHA? By goal: mood → EPA-forward (≥60% EPA, >2:1, 1-2 g EPA; PMID: 21939614 , 31383846 , 31480057 ); pregnancy/eyes → DHA-adequate; triglycerides → DHA has a slight edge ( PMID: 29425187 ); general health → balanced, no magic ratio. Does DHA make you smarter or improve memory? Not in healthy adults — a Cochrane review found no cognitive benefit or protection from decline ( PMID: 22696350 ). DHA is structurally important for the developing brain (pregnancy/infancy), not a memory booster for grown-ups. Is EPA or DHA better for lowering triglycerides? Both work; head-to-head DHA lowers them slightly more, while also raising HDL and LDL; EPA wasn't linked to those cholesterol changes ( PMID: 29425187 ). A clinical dose is ~4 g/day EPA+DHA under medical supervision. Does fish oil help dry eyes or prevent macular degeneration? The best trials say no — DREAM found no dry-eye benefit over placebo ( PMID: 29652551 ) and AREDS2 found no slowing of advanced AMD ( PMID: 23644932 ). Which EPA:DHA ratio is best? There's no single magic ratio. EPA-forward (>2:1) for mood; DHA-adequate for pregnancy/eyes; pure EPA (prescription) for high-risk heart patients; balanced for everyone else. Triglyceride vs Ethyl Ester — the form that decides absorption Best Omega-3 Supplement — the full ranked buying guide All Omega-3 Guides Sublette ME, et al. "Meta-analysis of the effects of eicosapentaenoic acid (EPA) in clinical trials in depression." J Clin Psychiatry . 2011;72(12):1577-1584. PMID: 21939614 Liao Y, et al. "Efficacy of omega-3 PUFAs in depression: A meta-analysis." Transl Psychiatry . 2019;9(1):190. PMID: 31383846 Guu TW, et al. "International Society for Nutritional Psychiatry Research Practice Guidelines for Omega-3 Fatty Acids in the Treatment of Major Depressive Disorder." Psychother Psychosom . 2019;88(5):263-273. PMID: 31480057 Innes JK, Calder PC. "The Differential Effects of Eicosapentaenoic Acid and Docosahexaenoic Acid on Cardiometabolic Risk Factors: A Systematic Review." Int J Mol Sci . 2018;19(2):532. PMID: 29425187 Metherel AH, et al. "Compound-specific isotope analysis reveals no retroconversion of DHA to EPA but substantial conversion of EPA to DHA following supplementation." Am J Clin Nutr . 2019;110(4):823-831. PMID: 31204771 Sydenham E, et al. "Omega 3 fatty acid for the prevention of cognitive decline and dementia." Cochrane Database Syst Rev . 2012;(6):CD005379. PMID: 22696350 Asbell PA, et al. "n-3 Fatty Acid Supplementation for the Treatment of Dry Eye Disease (DREAM)." N Engl J Med . 2018;378(18):1681-1690. PMID: 29652551 Chew EY, et al. "Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration (AREDS2)." JAMA . 2013;309(19):2005-2015. PMID: 23644932 Rogers LK, Valentine CJ, Keim SA. "DHA supplementation: current implications in pregnancy and childhood." Pharmacol Res . 2013;70(1):13-19. PMID: 23266567 Serhan CN. "Pro-resolving lipid mediators are leads for resolution physiology." Nature . 2014;510(7503):92-101. PMID: 24899309 Bhatt DL, et al. "Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia (REDUCE-IT)." N Engl J Med . 2019;380(1):11-22. PMID: 30415628 Manson JE, et al. "Marine n-3 Fatty Acids and Prevention of Cardiovascular Disease and Cancer (VITAL)." N Engl J Med . 2019;380(1):23-32. PMID: 30415637 Nicholls SJ, et al. "Effect of High-Dose Omega-3 Fatty Acids vs Corn Oil on Major Adverse Cardiovascular Events (STRENGTH)." JAMA . 2020;324(22):2268-2280. PMID: 33190147 Bostrom JA, Beckman JA, Berger JS. "Summoning STRENGTH to Question the Placebo in REDUCE-IT." Circulation . 2021;144(6):407-409. PMID: 34370544 Olshansky B, et al. "Mineral oil: safety and use as placebo in REDUCE-IT and other clinical studies." Eur Heart J Suppl . 2020;22(Suppl J):J34-J48. PMID: 33061866 NIH Office of Dietary Supplements. "Omega-3 Fatty Acids: Fact Sheet for Health Professionals." ods.od.nih.gov