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Fatty acid

Fish Oil

Fish oil is oil from fatty fish that supplies the long-chain omega-3 fats EPA and DHA. These fats come from marine algae and build up in fish through the food chain.

Also listed as Fish Oil Concentrate

LongevityCardiovascularBone & JointImmune SupportEssential Health

What it is studied for

The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.

Oxidative stressLongevityModerateA3 studies
Blood pressureCardiovascularModerateA3 studies
Joint ComfortBone & JointModerateA3 studies
Immune SupportModerateA3 studies
Essential HealthModerateA3 studies
InflammationModerateA3 studies
All 12 rated effectsGrouped by health goal, with the publications behind each rating

What is in fish oil?

Fish oil supplies the long-chain omega-3 fats eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These fats are components of cell membranes; DHA is particularly concentrated in the brain and retina. They ultimately come from marine microalgae and accumulate in fish through the food chain. 1

Plant foods such as flaxseed and walnuts mainly supply a different omega-3, ALA. The body can convert ALA to EPA and DHA, but conversion is limited. Algal oil is an alternative source of preformed DHA, and some products also contain EPA. 1

A lower blood-fat result is only one part of the story

The clearest finding in the Cochrane heart-disease review was lower triglycerides, one type of fat measured in blood. The same review found little or no effect on overall deaths or cardiovascular events. That distinction matters when a capsule is promoted broadly as “heart healthy.” 2

Key studies

The most recent publications linked to Fish Oil's ratings.

Immunomodulatory effect of fish oil and its polyunsaturated fatty acid components2024Regular use of fish oil supplements, Life's Essential 8 score, and cardiovascular mortality in people with type 2 diabetes: a longitudinal cohort study.2024The Effects of Fish Oil on Cardiovascular Diseases: Systematical Evaluation and Recent Advance2022Dietary Fish, Fish Nutrients, and Immune Function: A Review2021Anti-inflammatory effect of fish oil in human adipose tissue2021
All 22 studiesEvery publication linked to Fish Oil

Why people take it

Cardiovascular22.2%
Cognition21.4%
Essential Health21.2%
Immune Support15.1%
Bone & Joint5.8%
Longevity5.3%

SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.

Questions people ask

Is 1,000 mg fish oil the same as 1,000 mg omega-3?

No. A typical NIH example contains 180 mg EPA and 120 mg DHA within 1,000 mg of fish oil. The label gives the actual amounts. 1

Can fish oil lower triglycerides?

Yes. The Cochrane review found an average reduction of about 15% with increased EPA and DHA intake. Cholesterol did not show the same clear response. 2

Should everyone take it for the heart?

VITAL found no significant reduction in its main combined cardiovascular outcome. BfR does not consider concentrates necessary for healthy people who regularly eat fish. 3 4

Is a higher dose better for joints?

Not in the knee-osteoarthritis dose-comparison trial: the lower-dose mixture performed better for pain and function at two years. Neither was compared with placebo. 5

Can I get DHA without fish?

Yes. Algal-oil supplements provide preformed DHA, and some also supply EPA. 1

What is the main high-dose caution?

A dose-related increase in atrial fibrillation was found in people with heart disease or risk factors, greatest at 4 g daily in the reviewed trials. 4

Sources

  1. Omega-3 Fatty Acids: Fact Sheet for Health Professionals NIH Office of Dietary Supplements, 2025