EPA and DHA are both omega-3 fatty acids, and most fish oil labels list both. They are not interchangeable. DHA is structural — it is a building block of brain and retinal tissue. EPA is more involved in signalling pathways, including the body's normal inflammatory response.
The short version
| EPA | DHA | |
|---|---|---|
| Full name | Eicosapentaenoic acid | Docosahexaenoic acid |
| Chain length | 20 carbons | 22 carbons |
| Main role | Signalling molecules; inflammatory response | Structural component of cell membranes |
| Concentrated in | Circulation and tissues broadly | Brain and retina |
Why ALA is not a substitute
Plant sources — flaxseed, chia, walnuts — provide ALA (alpha-linolenic acid), a shorter omega-3. The body can convert ALA into EPA, and then a little of that into DHA, but the conversion is inefficient in humans. Published estimates put ALA to EPA conversion in the single-digit percentages, and ALA to DHA lower still.
This is not an argument against eating flaxseed. It is an argument against assuming flaxseed covers your EPA and DHA. If you do not eat oily fish, direct EPA and DHA — from fish oil or from algae, if you are vegetarian — is the shorter route.
The label problem
This is where fish oil gets deliberately confusing. A bottle saying "1,000mg Fish Oil" is telling you the weight of the oil, not the omega-3 content. A typical unconcentrated fish oil is roughly 30% EPA and DHA combined, so 1,000mg of oil might carry 300mg of actual omega-3.
Look for the EPA and DHA figures listed separately, in milligrams, per serving. If a label gives you only the total fish oil weight, or only a combined "omega-3" number without the split, you cannot compare it to anything.
Also check the serving size. "1,200mg per serving" where a serving is two softgels is a very different product from the same figure per single softgel.
How much do you need?
There is no US RDA for EPA and DHA specifically. Several health bodies suggest a combined intake in the region of 250–500mg a day for general health in adults, which is roughly what two servings of oily fish a week provides. Higher intakes are used in clinical research for specific outcomes, but those are studied under medical supervision and are not a general recommendation.
Why the fish species matters
Larger, longer-lived predatory fish accumulate more mercury and other contaminants through the food chain. Smaller, shorter-lived fish — sardines, anchovies, mackerel — accumulate substantially less. A fish oil sourced from small fish starts from a cleaner raw material, before any purification.
If a label does not say what fish the oil came from, that is worth noticing.
Practical notes
- Take it with a meal containing some fat. Omega-3 absorption improves considerably with food.
- If you get a fishy repeat, freezing the softgels before taking them helps.
- Omega-3 oxidises. Buy a size you will finish, keep it out of sunlight and heat.
What we do
Our omega-3 provides 180mg EPA and 120mg DHA per 1,000mg softgel, sourced from sardines and anchovies. Both figures are on the label separately. At two softgels a day that is 600mg of combined EPA and DHA, which sits above the general-health range most bodies suggest.
An honest limitation: this is a gelatin softgel, so it is not vegetarian. If you need a plant-based option, an algae-derived DHA supplement is the equivalent, and we do not currently make one.
Before you start
Omega-3 can affect blood clotting at higher doses. If you take warfarin or another anticoagulant, or have surgery scheduled within a fortnight, talk to your doctor first. Do not take it if you have a fish allergy.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
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