Eicosatetraenoic acid

Fatty-acidBest with a meal

What is it

Eicosatetraenoic acid (ETA) is a 20-carbon polyunsaturated fatty acid with four double bonds. The most familiar isomer is arachidonic acid (omega-6, 20:4n-6); other ETA isomers, such as 20:4n-3, occur in some marine and plant sources.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Muscle growth (arachidonic acid)

Limited Evidence

A few small RCTs in resistance-trained men suggest 1.5 g/day may modestly increase lean mass and strength gains; results are not consistent across studies.

How it works

ETAs are substrates for cyclooxygenase and lipoxygenase enzymes, generating eicosanoids that regulate inflammation, immune function, and vascular tone. Arachidonic acid is the major precursor of pro-inflammatory series-2 prostaglandins and series-4 leukotrienes, but it also yields anti-inflammatory and resolution mediators. Some plant-source ETAs (from green-lipped mussel oil, for example) are marketed for anti-inflammatory effects.

Dosage

No RDA for ETA specifically. Arachidonic acid intake from a typical Western diet is around 100-250 mg/day; supplements range from 250-1000 mg/day. DSLD does not report a median.

When and how to take it

Fat-soluble; take with a fat-containing meal to support absorption.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Arachidonic acid (ARASYN)

Used in some sports supplements.

Triglyceride form; absorbed with dietary fat.

Ethyl ester

Found in some concentrated fatty-acid products.

May have lower bioavailability than triglyceride form.

Safety

Arachidonic acid supplementation at doses up to 1.5 g/day has been studied in healthy adults without serious adverse effects. Theoretical concerns about increasing inflammation or platelet activation have not been clearly borne out in short-term studies.

Who should be cautious

People with bleeding disorders or on anticoagulant medication should consult a clinician. Those with active inflammatory conditions should weigh potential pro-inflammatory effects.

Interactions

Theoretical additive effects with NSAIDs (via prostaglandin pathways) and anticoagulants (via platelet effects). No clear clinical interaction documented.

Food sources

Egg yolk, 1 large

Amount
~50 mg arachidonic acid
%DV
—

Chicken liver, 3 oz

Amount
~200 mg arachidonic acid
%DV
—

Frequently asked questions

Is arachidonic acid the same as ETA?⌄

Arachidonic acid is the most common ETA isomer (20:4n-6). 'ETA' on a label may refer to this or to a related isomer.

Does it cause inflammation?⌄

It is a precursor to both inflammatory and resolving mediators. Short-term supplementation studies have not shown systemic inflammatory harm in healthy adults.

References

Eicosatetraenoic acid on Wikidata — Wikidata link

Eicosatetraenoic acid on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Eicosatetraenoic acid (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.