You have a bottle of omega-3 in your hand. The label says '1000mg of omega-3' but when you look at the details you see 180mg EPA and 120mg DHA. Is it good? Bad? Does it really matter?
The confusion is understandable. For years we were sold omega-3 as a single magical compound. The reality is that EPA and DHA are two completely different molecules with distinct functions in your body. Choosing between one or the other (or the correct ratio) can make the difference between a supplement that works and one that gathers dust in your cupboard.
This guide explains exactly what each one does, when to prioritise EPA over DHA (or vice versa), and how to read an omega-3 label without needing a doctorate in biochemistry. Everything backed by studies, without empty marketing.
- EPA (eicosapentaenoic acid) reduces inflammation, improves mood and protects the heart; prioritise it if you're looking to reduce depression or inflammatory markers
- DHA (docosahexaenoic acid) builds brain membranes, improves memory and cognitive function; critical during pregnancy, childhood and for prevention of cognitive decline
- Both work together: EPA dominates in blood and peripheral tissues, DHA concentrates in the brain and retina; most people need both, not just one
- The ratio matters according to your goal: 2:1 EPA:DHA for inflammation/mood, 1:1 or more DHA for cognitive function and pregnancy
- The total dose of EPA+DHA matters more than the percentage of total omega-3: aim for at least 500mg EPA+DHA combined per capsule, ideally 1000-2000mg daily
What are EPA and DHA exactly
EPA and DHA are long-chain polyunsaturated omega-3 fatty acids. Both have 20+ carbon atoms with multiple double bonds that make them flexible and reactive. But that's where the similarities end.
EPA has 20 carbons and 5 double bonds (20:5n-3 in technical nomenclature). It is the quintessential anti-inflammatory molecule in the omega-3 world. Your body uses it primarily to produce series 3 eicosanoids—signalling molecules that reduce inflammation, dilate blood vessels and modulate clotting.
DHA has 22 carbons and 6 double bonds (22:6n-3). That extra flexibility makes it the favoured structural component of excitable membranes: brain (40% of brain omega-3s are DHA), retina (60% of rod and cone lipids), sperm cells.
Both come primarily from oily fish and marine algae. Your body can make tiny amounts from ALA (the plant-based omega-3 from walnuts and flax), but the conversion is so inefficient (typically <10% to EPA, <1% to DHA) that it doesn't count towards real needs.
How EPA and DHA work (different mechanisms)
EPA: the anti-inflammatory firefighter
When you consume EPA, it incorporates into cell membranes, displacing arachidonic acid (pro-inflammatory omega-6). When a cell receives an inflammation signal, the enzymes phospholipase A2 and COX release these fatty acids to manufacture eicosanoids.
If the membrane is loaded with arachidonic acid, you produce series 2 prostaglandins and series 4 leukotrienes (pro-inflammatory). If it's loaded with EPA, you produce series 3 prostaglandins and series 5 leukotrienes (anti-inflammatory or neutral).
Studies in patients with rheumatoid arthritis show that 3-4g daily of EPA reduces morning stiffness and the number of painful joints compared with placebo. The mechanism: less production of IL-1β and TNF-α, cytokines that perpetuate chronic inflammation.
EPA also modulates the endocannabinoid system and increases serotonin availability. Recent meta-analyses place the efficacy of EPA (>60% of total omega-3) in major depression comparable to SSRIs in mild-to-moderate cases, without the sexual or weight side effects.
DHA: the architect of the brain
DHA is not an anti-inflammatory actor, it is a structural component. Neurons have incredibly active membranes: they receive thousands of signals per second, integrate information, fire action potentials. For that to work they need fluidity and the ability to form microdomains (lipid rafts) where receptors cluster.
97% of brain omega-3 is DHA. Functional magnetic resonance imaging studies show that high blood DHA levels correlate with greater hippocampal volume (memory) and better default mode network connectivity (abstract thinking, planning).
During the third trimester of pregnancy, the foetus accumulates 50-70mg of DHA daily to build the brain. A trial in mothers who received 800mg DHA vs placebo showed that their children assessed at age 4 had 4.5 points higher verbal IQ.
It also protects the retina. DHA makes up 60% of the lipids in photoreceptors and is essential for light signal transduction. DHA deficiency is associated with age-related macular degeneration.
Study-backed benefits: EPA vs DHA
When to prioritise EPA
Depression and mood disorders. A meta-analysis of 26 trials (n=1,458) found that supplements with EPA:DHA ratio ≥2:1 significantly reduce depressive symptoms vs placebo. Supplements with more DHA than EPA showed no effect. The effective dose: 1-2g EPA daily.
Triglyceride reduction. EPA reduces hepatic production of VLDL (very low-density lipoproteins that transport triglycerides). A study with 4g daily of EPA ethyl ester (Vascepa) reduced triglycerides by 20-30% and cardiovascular events by 25% in patients with elevated triglycerides already treated with statins.
Systemic inflammatory markers. EPA reduces CRP (C-reactive protein) and IL-6 in people with obesity, metabolic syndrome or cardiovascular disease. Especially useful if your blood work shows CRP >3 mg/L.
Chronic joint pain. Trials in rheumatoid arthritis and osteoarthritis show that 2.6-3g EPA+DHA (with EPA predominance) reduce pain, stiffness and use of non-steroidal anti-inflammatory drugs after 12-24 weeks.
When to prioritise DHA
Cognitive function and memory. Observational studies show that high blood DHA levels are associated with 47% lower dementia risk. Supplementation trials show benefit especially in people with mild cognitive impairment: 900mg DHA daily improves episodic memory after 24 weeks.
Pregnancy and foetal development. The scientific consensus is clear: 200-300mg DHA daily during pregnancy improves the baby's neurological development. Most prenatal supplements already include this amount.
Eye health. DHA protects against dry age-related macular degeneration (though it doesn't stop wet form). The AREDS2 formulation, backed by NIH, includes 350mg DHA + 650mg EPA to slow progression of intermediate macular degeneration.
Children with ADHD. Meta-analysis of 16 trials (n=1,514 children) showed that omega-3 supplementation (especially DHA) improves attention, hyperactivity and impulsivity. Modest but consistent effect: 0.2-0.3 standard deviations vs placebo.
Skin and skin barrier. DHA improves membrane fluidity in keratinocytes and reduces transepidermal water loss. Useful in people with very dry skin or atopic dermatitis.
EPA:DHA ratio: what science says
There is no universal optimal ratio. The correct ratio depends on your goal:
For depression, anxiety, inflammation: ratio 2:1 or 3:1 (EPA:DHA). Example: 1000mg EPA + 500mg DHA. The strongest evidence is in this range.
For cognitive function, pregnancy, children: ratio 1:1 or even inverted (more DHA). Example: 500mg EPA + 700mg DHA. Prioritise DHA without eliminating EPA because both work together.
For general cardiovascular prevention: ratio 1:1 to 2:1 works well. The largest studies (GISSI-Prevenzione, JELIS) used balanced ratios.
For aggressive triglyceride reduction: EPA almost pure (such as Vascepa with 96% EPA). Here EPA in isolation is justified because the goal is specifically hepatic.
Most fish oils have a ratio close to 1.5:1 (EPA:DHA) because it reflects the natural profile of oily fish. That works perfectly for the 80% of people seeking general cardiovascular, brain and anti-inflammatory health benefits.
Recommended doses according to goal
Generic recommendations to 'take omega-3' are useless. What matters is the combined dose of EPA+DHA, not the total of 'fish oil' or 'total omega-3'.
General maintenance (prevention in healthy adults): 500-1000mg EPA+DHA combined daily. This is what the American Heart Association recommends for the general population.
Depression or anxiety: 1000-2000mg EPA daily (with some DHA, ratio 2:1 or 3:1). Lower doses don't show consistent effect in trials.
Elevated triglycerides: 2000-4000mg EPA+DHA daily. You need pharmacological doses here, not maintenance doses. Consult your doctor if you take statins.
Cognitive function (prevention of decline): 500mg DHA + 300-500mg EPA daily. If you already have mild decline, some studies use up to 900mg DHA.
Pregnancy: minimum 200mg DHA daily throughout pregnancy, ideally 300mg. EPA optional but beneficial (200-300mg).
Rheumatoid arthritis or chronic inflammation: 2600-3000mg EPA+DHA combined, with EPA predominance. You need a minimum of 12 weeks to see effect.
Don't assume that 'more is better'. Doses above 5g daily can increase bleeding risk (especially if you take anticoagulants) and provide no additional benefits in most contexts.
How to choose a quality omega-3
The label on an omega-3 is like a candidate's CV: what it doesn't say is as important as what it does.
Look at the mg of EPA and DHA, not the total omega-3. A bottle can say '1400mg of omega-3' but only provide 200mg EPA + 150mg DHA. The rest are other omega-3s (ALA, DPA) without the scientific backing of EPA/DHA.
Chemical form: natural triglycerides (TG), re-esterified triglycerides (rTG) or ethyl esters (EE). TG and rTG have better absorption than EE, especially if you take omega-3 on an empty stomach. If you only find EE, take it with fatty food.
Third-party certification: IFOS (International Fish Oil Standards) or Friend of the Sea certify purity (heavy metals, PCBs, dioxins) and actual concentration vs label. Not all oils have them, but it's an extra guarantee.
Freshness: omega-3s oxidise. Look for 'peroxide value <5 meq/kg' or 'TOTOX <26'. If the label doesn't mention freshness, at least check that it includes vitamin E (tocopherols) as an antioxidant.
Realistic serving size: if you need 2000mg EPA+DHA daily and each capsule provides 300mg, you'll have to take 7 capsules. That's impractical. Look for high concentrations (500-1000mg EPA+DHA per capsule).
At Longevitalis we have developed 3 complementary protocols—LongeviNocturno for nighttime repair, Vitalis Renova+ for morning cellular renewal and LongeviSkin for skin from within. All with clinical doses, formulated in Spain under GMP. Vitalis Renova+ includes omega-3 in the form of re-esterified triglycerides with an optimal balanced EPA:DHA ratio for cardiovascular and brain prevention, alongside other pillars of cellular longevity.
Side effects and contraindications
Omega-3 is one of the safest studied supplements. But like any bioactive molecule, it has considerations:
Digestive: fishy burps, stomach upset. Solution: take with food, freeze the capsules, or look for enteric form (coating that dissolves in the intestine, not the stomach).
Bleeding: EPA and DHA reduce platelet aggregation. At normal doses (<3g daily) there's no problem. If you take anticoagulants (warfarin, apixaban) or antiplatelet agents (aspirin, clopidogrel), consult your doctor before exceeding 2g daily.
Interaction with blood pressure medication: omega-3 can slightly lower blood pressure. If you take blood pressure medication, monitor your blood pressure when starting supplementation.
Allergic reactions: if you're allergic to fish or shellfish, be careful. Highly purified oils are usually free of allergenic proteins, but risk exists. Alternative: algae-based omega-3 (100% vegetarian, DHA only or EPA+DHA depending on the strain).
Pregnancy: omega-3 is safe and beneficial. Avoid cod liver oil (excess vitamin A). Look for oils certified low in mercury.
Frequently asked questions
Can I get enough EPA and DHA from diet alone?
Yes, but it requires commitment. You need 2-3 weekly servings of oily fish (salmon, mackerel, sardines, anchovies). A tin of sardines provides ~1000mg EPA+DHA. The problem: many people don't eat fish regularly, or choose varieties low in omega-3 (hake, sea bream). Supplementation ensures consistent dosing without worrying about mercury in fish.
Is omega-3 from flaxseed or walnuts just as effective?
No. Those sources provide ALA (alpha-linolenic acid), which your body converts to EPA and DHA with poor efficiency: typically <10% to EPA, <1% to DHA. For real needs, ALA is not interchangeable with EPA/DHA. Useful as a complementary source, insufficient as the only source.
How long until I notice effects?
Depends on your goal. Triglycerides drop in 4-6 weeks. Cognitive function and memory: 12-24 weeks. Depression: 6-12 weeks. Joint pain: minimum 12-16 weeks. Omega-3s are not aspirin, they are structural molecules that integrate gradually into membranes. Patience is key.
Better to take omega-3 on an empty stomach or with food?
With fatty food always. Omega-3s are lipids and absorb better with other lipids. If you take capsules on an empty stomach, absorption can drop by 50%. Breakfast with avocado, eggs or nuts is ideal. If you can only take it on an empty stomach, look for rTG or TG form (better absorption than ethyl esters).
Can vegans meet DHA needs?
Yes, through algae-derived omega-3 supplements (Schizochytrium, Nannochloropsis). Algae produce EPA and DHA directly; fish accumulate them by eating algae. Algae supplements provide 200-400mg DHA per capsule, with no ocean impact. Good brands: Opti3, Testa, Vegetology.
Can I take EPA only if I want an anti-inflammatory effect?
You can, but it's not optimal. Although EPA is the main anti-inflammatory actor, DHA also converts to resolvins and protectins (mediators that actively resolve inflammation, not just block it). A 2:1 or 3:1 EPA:DHA ratio usually works better than pure EPA in real-world contexts, except very elevated triglycerides where pure EPA (Vascepa) has specific indication.
Conclusion: EPA or DHA?
The honest answer: both, in the right ratio for your goal.
If you're looking to reduce inflammation, improve mood or lower triglycerides, prioritise EPA (ratio 2:1 or 3:1). If you're looking to protect cognitive function, are pregnant or want to support child development, prioritise DHA (ratio 1:1 or more DHA). If you simply want general prevention, a balanced 1.5:1 ratio works perfectly.
What's critical is not becoming obsessed with the perfect ratio, but reaching the minimum effective dose of EPA+DHA combined: 1000-2000mg daily depending on goal, from a product certified for purity and freshness, taken with fatty food.
And remember: the best omega-3 is the one you actually take consistently. Not the one with the most sophisticated ratio that you forget in the drawer.
Disclaimer: This information is for educational purposes and does not replace professional medical advice. Consult your doctor before starting any protocol, especially if you take medication or have pre-existing conditions.
