INGREDIENTS

EPA vs DHA: how much omega-3 should you take, and fish or algae?

What EPA and DHA are, the amounts studied, fish oil versus algae oil for plant-based eaters, the omega-3 index test, blood-thinner caution, and how to avoid fishy aftertaste.

The short version

EPA and DHA are the long-chain omega-3s found in fish and algae. DHA is concentrated in the brain and retina, and the body converts only a small share of plant omega-3 (ALA) into either one.
There is no official daily target for EPA and DHA. Most people in large trials took 1 g a day or less, and the FDA considers up to 5 g a day of EPA plus DHA from supplements safe.
Algae oil is a plant-based source of DHA, and some algae oils also contain EPA. In one study, DHA from algae oil capsules raised blood DHA as well as cooked salmon did.
The omega-3 index measures EPA plus DHA in red blood cells. Researchers propose 8 to 11% as a target range; many people test lower.
If you take a blood thinner, check with your doctor first. Higher doses are linked to a modestly higher risk of atrial fibrillation, an irregular heart rhythm.

What is the difference between EPA and DHA?

EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are the two long-chain omega-3 fats in fish, fish oil and algae oil. Most supplements contain both, in different ratios.

DHA is especially concentrated in the retina, brain and sperm. Plant foods such as flax, chia and walnuts supply a different omega-3, ALA, and the body converts less than 15% of it into EPA and DHA. Eating EPA and DHA directly, from food or supplements, is the practical way to raise your levels.

A typical 1,000 mg fish oil capsule provides about 180 mg of EPA and 120 mg of DHA, so fish oil usually leans toward EPA. Algae oils usually lean toward DHA. Always read the EPA and DHA amounts, not the total oil weight.

How much EPA and DHA should you take?

No official recommended amount exists for EPA and DHA; only ALA has one (1.1 g a day for women and 1.6 g for men). The FDA considers supplements providing up to 5 g a day of EPA and DHA combined safe when used as directed.

Studied amounts vary. In a 2021 analysis of seven large trials covering more than 81,000 people, about 73% were in trials testing 1 g a day or less, and the rest were in trials testing more than 1 g a day.

More is not automatically better. In that same analysis, omega-3 supplements were linked to a 25% higher relative risk of atrial fibrillation overall: about 12% higher in trials of 1 g a day or less and about 49% higher in trials above 1 g. Most participants were around 65 and many had heart risk factors, so ask your doctor before taking high amounts.

Fish oil or algae oil: which is better?

Both work for raising omega-3 levels. Choose fish oil if you want more EPA per capsule, and algae oil if you eat plant-based or prefer to avoid fish.

Algal oil supplements usually provide about 100 to 300 mg of DHA per serving, and some also contain EPA. In a randomized study of 32 healthy adults, 600 mg a day of DHA from algae oil capsules raised DHA in blood plasma and red blood cells as much as the same amount of DHA from cooked salmon, by about 80% and 25% respectively over two weeks.

Apiece offers both an EPA-rich, fish-derived omega-3 and an algae-based DHA, so plant-based eaters have an option.

What is the omega-3 index test?

The omega-3 index is a blood test that measures EPA plus DHA as a percentage of the fatty acids in your red blood cells. It is meant to reflect your intake over recent months rather than your last meal.

Researchers who developed the test propose a target range of 8 to 11%. In one self-selected group of almost 2,000 Dutch adults, the average was about 6%, and only a minority were in range. In a heart failure trial, about 850 to 880 mg a day of EPA and DHA raised the average index from about 4.8% to 6.7% over three months.

Response varies a lot from person to person, so the authors suggest retesting after three to four months and adjusting. Note that the lead author runs a lab that performs this test. If you have a recent result, Apiece lets you add it, and amounts adjust to it.

Is omega-3 safe with blood thinners?

Check with your doctor first. The NIH Office of Dietary Supplements notes that omega-3 supplements might interact with blood thinners such as warfarin.

A 2023 review reported that bleeding events were slightly more common (about 0.1% a year) in trials using high doses. Tell your care team about any omega-3 you take, especially before a procedure, and if you take blood pressure medicines or medicines that suppress the immune system, which may also interact.

How do you avoid fishy aftertaste and keep omega-3 fresh?

Take omega-3 with your main meal. Fat in the meal greatly improves absorption, and taking it with food can reduce fishy burps and stomach upset.

Side effects are usually mild: an unpleasant taste, bad breath, heartburn, nausea, loose stools, headache or smelly sweat. Freshness matters too. In a test of 171 omega-3 products sold in North America, half exceeded voluntary limits for oxidation markers, and bulk liquid oils and flavored products scored worse than plain capsules.

Keep the container closed and away from heat and light.
Check the best-by date and don't use a product past it.
If capsules or oil smell strongly rancid, replace them.

Questions

Is EPA or DHA more important?

Both matter, and most supplements contain both. DHA is concentrated in the brain and retina, while fish oil tends to provide more EPA. If you eat no fish, an algae oil DHA supplement is a practical way to get long-chain omega-3s.

How much omega-3 should I take a day?

There is no official target for EPA and DHA. Most people in large trials took 1 g a day or less, and the FDA considers up to 5 g a day from supplements safe. Higher amounts are linked to a higher risk of atrial fibrillation, so ask your doctor before going above about 1 g.

Is algae oil as good as fish oil?

For DHA, yes. A randomized study found DHA from algae oil capsules raised blood DHA as much as cooked salmon. Algae oils usually provide more DHA than EPA, so check the label if you want EPA too.

What is a good omega-3 index?

Researchers who developed the test propose 8 to 11% as a target range. Many people test lower; in one large Dutch sample the average was about 6%. Retesting after three to four months shows how your intake is working.

Why does fish oil make me burp?

Fishy burps are a common, usually mild side effect. Taking omega-3 with your main meal, choosing fresh, unflavored capsules, and storing them away from heat and light usually helps.

Sources

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*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. This page is general information, not medical advice. Check with your doctor or pharmacist before starting a supplement, especially if you take medication, are pregnant or nursing, or have a health condition. Updated 2026-10-20.