Omega-3 (fish oil)

Also known as: EPA, DHA, Fish oil, Algal oil

Long-chain omega-3 fats from fish or algae. Best studied for triglycerides; EPA-rich formulas also studied for mood.

Common forms: Fish oil softgels · Algal oil (vegan) · Krill oil · Liquid

Draft summary, not yet reviewed by a qualified health professional · Last updated 2026-11-03

Talk to a healthcare professional first

This information is for education only and is not medical advice, diagnosis, or treatment. Supplements can interact with medications and health conditions. Check with your doctor or pharmacist before starting anything, especially if you take medication, are pregnant or breastfeeding, or have a health condition. These statements have not been evaluated by the FDA; supplements are not intended to diagnose, treat, cure, or prevent any disease.

What the evidence says

Heart health markers

AStrong evidence

Dose-response meta-analyses show EPA+DHA lowers triglycerides in a dose-dependent way. Note: a Cochrane review found little or no effect on heart attacks or deaths for most people.

Dose used in studies: 2–4 g/day EPA+DHA for triglycerides
Time to effect: 4–12 weeks
Most relevant for: People with elevated triglycerides

Studies (2)

Association Between Omega-3 Fatty Acid Intake and Dyslipidemia: A Continuous Dose-Response Meta-Analysis of Randomized Controlled Trials — J Am Heart Assoc, 2023 · Meta-analysis · PMID 37264945
Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease — Cochrane Database Syst Rev, 2020 · Meta-analysis · PMID 32114706

Low mood

BModerate evidence

Meta-analyses found omega-3s with a high EPA proportion (≥60% EPA) improved depressive symptoms; DHA-dominant formulas did not.

Dose used in studies: ~1 g/day EPA (EPA ≥ 60% of total)
Time to effect: 4–8 weeks

Studies (2)

Efficacy of omega-3 PUFAs in depression: A meta-analysis — Transl Psychiatry, 2019 · Meta-analysis · PMID 31383846
Effects of long-chain omega-3 polyunsaturated fatty acids on reducing anxiety and/or depression in adults; A systematic review and meta-analysis of randomised controlled trials — Prostaglandins Leukot Essent Fatty Acids, 2023 · Meta-analysis · PMID 37028202

Joint comfort

CLimited evidence

Marine oil supplements modestly reduced arthritis pain in a meta-analysis, mostly in inflammatory (rheumatoid) arthritis rather than osteoarthritis.

Dose used in studies: 2–3 g/day EPA+DHA
Time to effect: ~3 months

Studies (1)

Marine Oil Supplements for Arthritis Pain: A Systematic Review and Meta-Analysis of Randomized Trials — Nutrients, 2017 · Meta-analysis · PMID 28067815

Safety

Common side effects

Fishy aftertaste or burps
Stomach upset
Loose stools

Avoid or ask your doctor first if

You have a fish or shellfish allergy (use algal oil)
You have atrial fibrillation (high doses linked to increased risk)

Pregnancy & breastfeeding

Likely safe at normal dietary doses — confirm with your provider.

Upper limit

FDA considers up to 5 g/day combined EPA+DHA from supplements safe

Medication interactions

moderateBlood thinners: High doses may increase bleeding risk.
moderateAntiplatelets: High doses may increase bleeding risk.
minorBlood pressure medications: May slightly add to blood-pressure lowering.

This list covers common medication classes only and is not exhaustive.

Buying tips

Look for third-party testing seals (USP Verified, NSF Certified, or Informed Choice) and match the form and dose used in studies.

Where to buy (affiliate)