fatty acid
Omega-3 and Fish Oil: EPA, DHA, Forms and Safety
Also known as fish oil, omega-3 fatty acids, EPA, DHA, ALA, krill oil, algal oil, cod liver oil
Short answer
Omega-3s are fats the body uses to build cell membranes. ALA comes from plant oils; EPA and DHA come from fish, fish oil, krill oil and algal oil. A typical 1,000 mg fish oil capsule has about 180 mg EPA and 120 mg DHA. Ask your pharmacist first if you take warfarin [1].
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What is Omega-3 (Fish Oil)?
Omega-3s are polyunsaturated fats. The three studied most are ALA, EPA and DHA [1]. ALA is essential, which means it must come from food, and the body converts only a small share of it (under 15%) to EPA and DHA [1]. The body uses omega-3s as building blocks of cell membranes, for energy, and to make signaling molecules called eicosanoids; DHA is especially high in the retina, brain and sperm [1].
Forms of Omega-3 (Fish Oil) you'll see on labels
Fish oil
Contains EPA and DHA. A typical supplement has about 1,000 mg fish oil with 180 mg EPA and 120 mg DHA, but amounts vary widely [1].
Cod liver oil
Contains EPA and DHA plus vitamins A and D, in amounts that vary by product; vitamins A and D can be harmful in excess [1][2].
Krill oil
Contains omega-3s mainly as phospholipids. Some studies suggest slightly higher absorption than fish oil, others do not [1].
Algal oil
A plant-based (vegetarian) source, usually about 100–300 mg DHA; some also contain EPA [1].
Flaxseed oil
Contains ALA, not EPA or DHA [2].
Triglyceride vs ethyl ester
Natural triglycerides, re-esterified triglycerides and free fatty acids are absorbed somewhat better than ethyl esters, but all forms raise blood EPA and DHA [1].
How much Omega-3 (Fish Oil) do adults need?
NIH lists these Adequate Intakes (AI) for adults 19+, in grams per day. They apply to ALA only; no official intake is set for EPA or DHA. Reference values, not a personal recommendation.
| Group | Amount per day |
|---|---|
| Men 19+ | 1.6 g ALA |
| Women 19+ | 1.1 g ALA |
| Pregnancy | 1.4 g ALA |
| Lactation | 1.3 g ALA |
Upper limit: No UL has been set for any omega-3. FDA has concluded that supplements giving no more than 5 g a day of EPA plus DHA are safe when used as recommended [1].
How Omega-3 (Fish Oil) appears on a label
The fish oil amount on the front of a pack is not the same as the omega-3 amount. Check the Supplement Facts panel for the mg of EPA and DHA per serving: a typical 1,000 mg fish oil capsule has about 180 mg EPA and 120 mg DHA [1]. FDA has a Daily Value for total fat (65 g) but not for omega-3s, so labels show no % DV for them [1].
When to take Omega-3 (Fish Oil)
No official source names a best time of day to take fish oil or other omega-3 supplements, or says whether to take them with food. NIH notes that omega-3s are absorbed about as well as other dietary fats, at about 95% [1].
What to keep apart from Omega-3 (Fish Oil)
Warfarin (Coumadin) and similar anticoagulants
Fish oil may have antiplatelet effects at high doses and might raise INR with warfarin, though most research found 3–6 g a day did not significantly change anticoagulation [1]. Package inserts for prescription omega-3s say INR should be monitored. Ask your pharmacist.
Cod liver oil with other vitamin A or D supplements
Cod liver oil also provides vitamins A and D, which can be harmful in excess [2]. Count them in your totals.
Foods that contain Omega-3 (Fish Oil)
- Salmon
- Herring
- Sardines
- Mackerel
- Trout
- Oysters
- Flaxseed and flaxseed oil
- Chia seeds
- Walnuts
- Canola and soybean oil
- DHA-fortified eggs, milk and yogurt
Who should ask a doctor or pharmacist first
Talk to a doctor or pharmacist first if you take warfarin or another blood thinner [1]. Ask also if you have heart disease or a high risk of it: two large trials found 4 g a day of omega-3 supplements for several years slightly raised the risk of atrial fibrillation in these groups [1]. If you use cod liver oil, count its vitamins A and D, which can be harmful in excess [2].
Keep Omega-3 (Fish Oil) in a routine that fits
Supin schedules what you take by time of day, reminds you, and tells you when a bottle runs low.
Omega-3 (Fish Oil): questions people ask
No. A typical 1,000 mg fish oil capsule has about 180 mg EPA and 120 mg DHA [1]. Check the Supplement Facts panel for the EPA and DHA amounts.
Krill oil carries omega-3s mainly as phospholipids. Some studies suggest it is absorbed slightly better than fish oil, while others do not [1].
NIH says omega-3 supplements have not been found to contain methyl mercury, because it is removed during processing and purification [1].
Fish oil might raise INR when taken with warfarin, though most studies of 3–6 g a day found no significant change [1]. Ask your pharmacist or doctor before combining them.
Sources
- Omega-3 Fatty Acids: Fact Sheet for Health Professionals — NIH Office of Dietary Supplements
- Omega-3 Supplements: What You Need To Know — NIH National Center for Complementary and Integrative Health
Educational information, not medical advice. The amounts above are official reference values, not a recommendation for you. Check with your doctor or pharmacist before starting or changing supplements, especially if you take medication, are pregnant or have a health condition. Supin sells a subscription, not supplements. Last reviewed .