“Omega-3” is often used as if it were one thing. In practice, the omega-3s that matter most in marine nutrition are three distinct long-chain fatty acids — EPA, DHA, and DPA — and they are not interchangeable. They differ in structure, in where the body concentrates them, and, from a regulatory standpoint, in what can legally be said about them. That last point matters more than most articles on this topic mention: two of the three carry an authorized EU health claim, and one does not.
What the Three Actually Are
All three belong to the n-3 (omega-3) family of long-chain polyunsaturated fatty acids (LCPUFA) — found primarily in fatty fish, fish oil, and some marine algae.
- EPA (eicosapentaenoic acid) — a 20-carbon fatty acid, generally the most abundant of the three in standard fish oil.
- DHA (docosahexaenoic acid) — a 22-carbon fatty acid, and the omega-3 most concentrated in neural and retinal tissue.
- DPA (docosapentaenoic acid) — a 22-carbon fatty acid that sits structurally between EPA and DHA.
They are related, but each has a distinct carbon-chain length and double-bond structure, and the body handles each one differently.
What EU Regulators Have Actually Authorized
This is the part most comparison content skips. Under the EU Nutrition and Health Claims Regulation, EFSA has issued a specific set of authorized claims for EPA and DHA, each tied to an exact daily intake (EU Register on Nutrition and Health Claims, Regulation (EC) No 1924/2006 and Regulation (EU) 432/2012). The authorized claims include:
- Normal function of the heart — requires a daily intake of 250 mg of EPA and DHA.
- Maintenance of normal blood pressure — requires 3 g per day of EPA and DHA.
- Maintenance of normal blood triglyceride levels — requires 2 g per day of EPA and DHA.
- DHA contributes to the maintenance of normal brain function — requires a food providing at least 40 mg of DHA per 100 g and per 100 kcal.
- DHA contributes to the maintenance of normal vision — requires 250 mg of DHA per day.
- Maternal DHA intake contributes to normal brain and eye development of the fetus and breastfed infant — requires 200 mg of DHA per day in addition to the recommended daily omega-3 intake.
Each claim only applies at its stated intake level and under the conditions of use specified in the Register — it is not transferable to a lower dose or a different combination than the one specified.
DPA has no authorized EU health claim. EFSA has evaluated DPA primarily in the context of safety and tolerable upper intake levels alongside EPA and DHA — not as a substance with its own approved benefit statement. That does not mean DPA is inert; it means the specific regulatory step required to make a benefit claim about it in the EU has not been completed. Any description of DPA on a product page has to stay at the level of what it is rather than what it does.
How Much Is Considered Safe
EFSA's 2025 scientific opinion on tolerable upper intake levels for EPA, DHA, and DPA — evaluated individually and combined — found no adverse effects associated with intakes typically obtained from food in healthy adults and children. For supplemental intake, the panel noted no significant safety concern with:
- Combined EPA and DHA intake up to approximately 5 g per day
- EPA alone up to 1.8 g per day
- DHA alone up to 1 g per day
These are safety findings, not claim thresholds — they describe intake levels EFSA did not flag as a risk, not a recommended target.
Why the Distinction Is More Than Academic
Fish oil supplements vary widely in their EPA:DHA:DPA ratio depending on the source species and how the oil is processed. A product's actual composition — not just the word “omega-3” on the front of the label — determines which of the authorized claims, if any, it can legitimately carry, and at what serving size.
A supplement with a high EPA:DHA ratio and a small serving size may fall short of the 250 mg threshold needed even for the heart-function claim. Reading the actual EPA and DHA content per serving, not the total “omega-3” number, is the only way to know what a product can honestly promise.
The Takeaway
EPA, DHA, and DPA are three related but distinct marine fatty acids. EPA and DHA each carry specific, dose-conditioned EU health claims; DPA currently does not. Understanding that difference is the first step in reading any omega-3 label — including your own — honestly.
Sources
- EU Register on Nutrition and Health Claims (European Commission, ec.europa.eu) — heart function (250 mg EPA+DHA daily), brain function (≥40 mg DHA per 100 g and per 100 kcal; 250 mg daily), vision (250 mg DHA daily) — authorized under Commission Regulation (EU) 432/2012.
- EFSA-Approved Omega-3 Fatty Acid Health Claims (2014 Register compilation) — blood pressure (3 g EPA+DHA per day) and blood triglycerides (2 g per day) conditions of use.
- EFSA, “EFSA assesses safety of long-chain omega-3 fatty acids,” efsa.europa.eu — role and food sources of EPA, DHA, and DPA; tolerable-upper-intake-level assessment context.
- EFSA scientific opinion on tolerable upper intake levels for EPA, DHA, and DPA (2025) — no-safety-concern figures for supplemental EPA+DHA (≤5 g/day), EPA alone (≤1.8 g/day), and DHA alone (≤1 g/day).
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