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Omega-3 (fish & algae oil)

EPA and DHA

Supplements. Modern nutrition.

Also called Fish oil, Krill oil, Cod liver oil, Algae oil

Pinyin: yú yóu

Spanish: Aceite de pescado (omega-3)

May add to bleeding risk

Two fats, EPA and DHA, found in oily fish and algae, most often taken to lower blood fats (triglycerides) and for heart health.

Did you know? Fish do not make their own omega-3 fats, because they get EPA and DHA by eating algae.

What it may help, and how strong the proof is

Cholesterol. At high doses (about 2 to 4 grams a day), omega-3 clearly lowers triglycerides, a blood fat. Regular capsules do much less. It can slightly raise LDL (bad) cholesterol.
Strong proof
Heart health. Large trials of regular doses (about 1 gram a day) did not show fewer heart attacks in healthy people. A prescription high-dose EPA drug cut heart events in some high-risk people with high triglycerides.
Early proof
Low mood. Some trials add omega-3 to antidepressants. Reviews show only a small benefit, mostly with EPA-rich products.
Early proof
Memory & focus. Large trials in healthy older adults have not shown that fish oil protects memory or slows thinking decline.
Not supported

Parts of the body

Heart & vessels, Liver, Brain & mind

Traditional use

Coastal peoples such as the Inuit ate oily fish and seal fat for generations. In the 1900s, cod liver oil was a common children's supplement in Europe and North America, mainly for vitamins A and D.

How it is classified

Herbal actions: Nutritive, Anti-inflammatory, Circulatory. Energy: neutral.

How people take it

Common capsules give 250 to 1,000 mg of EPA and DHA a day. Triglyceride-lowering trials used 2 to 4 grams a day, usually under medical care. Check the label for EPA plus DHA, not the total fish oil.

Capsule, oil and food.

Where to get it

Oily fish such as salmon, sardines, mackerel and herring are the main food sources. Algae oil is a plant-based option for people who avoid fish. Capsules, liquids and gummies are sold in stores and online, and prescription EPA is sold at pharmacies.

Be careful

Common side effects are fishy burps, upset stomach and loose stools. High doses may add to bleeding risk, especially with blood thinners, and some analyses link high doses to more atrial fibrillation (an irregular heartbeat). Cod liver oil is high in vitamin A, so avoid high doses in pregnancy.

Avoid if: bleeding disorders; fish allergy; before surgery.

Mixing with other things

Use caution
Blood thinners (warfarin, Eliquis, Xarelto, Plavix, daily aspirin)
High doses may add to bleeding risk with warfarin, aspirin or similar drugs.
Worth knowing
Blood pressure medicine (lisinopril, amlodipine, losartan)
Can lower blood pressure a little, mainly at high doses.

Adds up with others that may slow blood clotting: , , , , , , , , , , , , , and 40 more.

The honest take

Eating oily fish about twice a week is a solid habit. Capsules lower triglycerides at high doses, but large trials of regular doses have not shown fewer heart attacks in healthy people. Some products are rancid (spoiled by oxidation) or hold less omega-3 than the label says.