In 30 seconds
- EPA and DHA are the long-chain omega-3s found in fish. Of the omega-3 from plants, the body converts less than 15% into EPA and DHA.
- DHA is abundant in the retina and the brain. At 250 mg a day, it has this authorised claim: “DHA contributes to maintenance of normal brain function.”
- EPA is the raw material for signalling molecules. At 250 mg a day of the two: “EPA and DHA contribute to the normal function of the heart.”
- In a review of 6 trials with 527 people, DHA lowered triglycerides more than EPA: their effects are not identical.
EPA and DHA are the two omega-3s in fish, but they do not do the same thing. DHA is a building block of the brain and the retina, and EPA is the raw material for signalling molecules. If you train or look after yourself, you need both: here is how they differ and how much of each your fish gives you.
What they are
They are long-chain omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). They are found mainly in oily fish and seafood 1.
There is a third omega-3 that gets a lot of attention: alpha-linolenic acid (ALA), the one in walnuts, flaxseed and chia. The body can convert it into EPA and DHA, but only a little: less than 15%, according to the US National Institutes of Health (NIH). That is why taking EPA and DHA directly, from fish or a supplement, is the only practical way to raise their levels 1.
Two omega-3 fats, two roles
DHA and EPA: how they differ
DHA: the structural omega-3
DHA is part of cell membranes, and it is especially abundant in the retina, the brain and sperm cells 1. During pregnancy it builds up very quickly in the baby's brain and retina, above all in the third trimester 1.
That is why the EU recognises, with a daily intake of 250 mg of DHA, that 2:
- DHA contributes to maintenance of normal brain function.
- DHA contributes to the maintenance of normal vision.
A varied and balanced diet and a healthy lifestyle are important.
EPA: the signalling omega-3
EPA is the raw material for the enzymes that make eicosanoids, molecules that regulate inflammation. The ones made from EPA tend to be much less active than those made from arachidonic acid, an omega-6 3.
When you take more omega-3, EPA and DHA gain ground in your cells, mostly at the expense of that arachidonic acid. This happens in a dose-dependent way, within days to weeks: a new balance is reached in about 4 weeks 3.
EPA and DHA are also the source of resolvins and protectins, anti-inflammatory molecules that, according to the studies, are involved in resolving inflammation 3.
Together: the heart
For the heart, the EU does not separate the two: what counts is the total. At 250 mg of EPA and DHA a day, it recognises that “EPA and DHA contribute to the normal function of the heart” 2. This is also the intake EFSA considers adequate for healthy adults 5.
Their effects are not identical
A systematic review gathered the trials that compared EPA and DHA separately: 6 studies with 527 people 4. It found some interesting differences:
- Triglycerides: both lowered them, and DHA lowered them more.
- Cholesterol: DHA raised HDL and also LDL, with larger LDL particles.
- Heart rate and blood pressure: DHA lowered heart rate and blood pressure more than EPA.
- Inflammation and glucose: no clear conclusions for either.
The authors see this as a sign that they act in different ways, still to be confirmed in larger studies 4. And in everyday life, fish and supplements give you both together.
DHA per portion
How much DHA an 85 g portion of fish gives you
How much EPA and DHA fish contains
Each species has its own ratio. There is almost always more DHA than EPA, and the gap between oily fish and white fish is huge 1:
| Fish | DHA | EPA |
|---|---|---|
| Farmed Atlantic salmon | 1,240 mg | 590 mg |
| Herring | 940 mg | 770 mg |
| Tinned sardines in tomato sauce | 740 mg | 450 mg |
| Mackerel | 590 mg | 430 mg |
| Sea bass | 470 mg | 180 mg |
| Rainbow trout | 440 mg | 400 mg |
| Prawns | 120 mg | 120 mg |
| Tinned light tuna in water | 170 mg | 20 mg |
| Cod | 100 mg | 40 mg |
Source: Office of Dietary Supplements, US National Institutes of Health. Varies with species, origin and preparation.
A portion of salmon or herring gives you more than 1,700 mg of EPA and DHA. A tin of light tuna, less than 200 mg. How much does what you eat in a week give you? Work it out with our omega-3 calculator.
And in supplements?
It depends on where the oil comes from. Algal oils, the plant-based option, usually provide mostly DHA, around 100-300 mg, and some also contain EPA 1.
Our Anchovy Omega-3 provides 540 mg of EPA and 360 mg of DHA in 3 softgels: 900 mg in total. That is more than three times the EPA and DHA reference for the heart. And its DHA exceeds the 250 mg a day set for the brain and vision claims. If you are weighing up products, we explain which omega-3 to buy.
Omega-3 index
EPA and DHA in the blood of 1,528 athletes
The omega-3 index: your EPA and DHA in the blood
There is a test that measures both together: the omega-3 index. It is the percentage of EPA and DHA in the membranes of your red blood cells. It reflects what you have taken over the last 120 days 1.
In a study of 1,528 US college athletes, the average index was 4.3%, and none of them reached the 8% used as a target 6. What moved it most was fish: each weekly portion of fish or seafood raised it by 0.27% 6.
Do you need to choose one?
No. For most people, the practical thing is to check two numbers on the label:
- EPA + DHA: a total of at least 250 mg a day.
- DHA: 250 mg a day if you also want it for the brain and vision.
And without overdoing it: EFSA concluded that up to 5 g a day of EPA and DHA from supplements raises no safety concerns in adults 5. If you want to know everything they do, carry on with omega-3: what it does.
Frequently asked questions
What is the difference between EPA and DHA?
Which is better, EPA or DHA?
They do not compete: they complement each other. For the heart, what counts is the two combined, 250 mg a day. For the brain and vision, the reference is 250 mg of DHA a day.
Does the omega-3 in walnuts or flaxseed give you EPA and DHA?
Very little. Walnuts, flaxseed and chia provide alpha-linolenic acid, and the body converts less than 15% of it into EPA and DHA. The practical way to get them is fish or a supplement.
How much DHA do I need a day?
For DHA, the EU sets 250 mg a day: this is the amount in its authorised claims on the brain and vision. For the heart, the reference is 250 mg of EPA and DHA combined.
Sources
- Office of Dietary Supplements, National Institutes of Health. Omega-3 fatty acids: fact sheet for health professionals. View publication
- Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods. View publication
- Calder PC. Omega-3 fatty acids and inflammatory processes. Nutrients. 2010;2(3):355-374. View publication
- 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. View publication
- EFSA. EFSA assesses safety of long-chain omega-3 fatty acids. Press release, 27 July 2012. View publication
- Ritz PP, Rogers MB, Zabinsky JS, et al. Dietary and biological assessment of the omega-3 status of collegiate athletes: a cross-sectional analysis. PLoS One. 2020;15(4):e0228834. View publication
Information based on published studies. It does not replace the advice of a doctor or registered dietitian. The results describe what was measured in each study, not the properties of any specific product.
