GUIDE — SUPPLEMENT

Omega-3 (EPA/DHA): Triglycerides, Inflammation, and the REDUCE-IT Evidence

Dr. Regina Druz, MD, MBA, FACC, FMCP-M·Reviewed May 2026·4 min read
Quick summary

Omega-3 fatty acids EPA and DHA reduce triglycerides by 25–45% at therapeutic doses, lower inflammation, stabilize cardiac membranes, and have mild antihypertensive and antiplatelet effects. The REDUCE-IT trial showed 4 g/day prescription EPA reduced major cardiovascular events by 25%. OTC fish oil quality varies enormously. Most adults benefit from at least 1–2 g EPA+DHA daily from a quality, non-oxidized source.

Key clinical numbers

−25%
Major cardiovascular events (REDUCE-IT)
25–45%
Triglyceride reduction
4 g/day
Prescription EPA trial dose

REDUCE-IT (2019): 8,179 statin-treated patients with elevated triglycerides, 4 g/day prescription EPA vs. placebo. Triglyceride range reflects 2–4 g/day EPA+DHA. Individual results vary.

The evidence

Omega-3 fatty acids — specifically EPA and DHA — have more cardiovascular evidence behind them than almost any other supplement. They reduce triglycerides dose-dependently (2–4 g/day EPA+DHA reduces triglycerides by 25–45%), lower inflammation via prostaglandin and leukotriene pathways, and stabilize cardiac membranes, reducing arrhythmia risk.

The landmark REDUCE-IT trial (2018) showed that high-dose icosapentaenoic acid (4 g/day prescription EPA) reduced major adverse cardiovascular events by 25% in statin-treated patients with elevated triglycerides. This requires pharmaceutical-grade EPA at therapeutic doses — not standard over-the-counter fish oil.

Dose, form & what to look for

Dose

2–4 g/day EPA+DHA for cardiovascular benefit. Use triglyceride-form fish oil or prescription EPA (Vascepa) for maximum effect. Store refrigerated after opening. Choose products with EPA+DHA content clearly stated per serving and third-party testing for oxidation (TOTOX score below 10 is ideal).

Side effects & drug interactions

Bleeding & blood-pressure caution

High-dose omega-3 above 3 g/day has measurable antiplatelet effects. Patients on warfarin, aspirin, or DOACs should disclose omega-3 use to their physician. At standard doses of 1–2 g/day the risk is minimal for most patients but should still be disclosed. Omega-3 also has mild blood-pressure-lowering effects — monitor if on antihypertensives.

Frequently asked questions

Is OTC fish oil as good as prescription omega-3?+

For mild supplementation in healthy individuals, a high-quality OTC fish oil providing 1–2 g EPA+DHA daily is reasonable. For patients with significantly elevated triglycerides or established cardiovascular disease, prescription-grade EPA (Vascepa/icosapentaenoic acid) has far stronger trial evidence. The REDUCE-IT trial used pure EPA at 4 g/day — not a mixed EPA/DHA product.

How do I know if my fish oil supplement is high quality?+

Look for: triglyceride form (not ethyl ester), EPA+DHA content clearly stated per serving, third-party testing for oxidation (TOTOX score below 10), and a certificate of analysis on request. Rancid fish oil smells strongly fishy even before opening. Store refrigerated after opening — oxidized omega-3 is pro-inflammatory, not cardioprotective.

Can omega-3 replace heart medication?+

No. Omega-3 supplementation is a complementary strategy, not a replacement for prescribed cardiovascular medications. It works synergistically with statin therapy, blood pressure medications, and antiplatelet agents. Never stop or reduce prescribed medication in favor of supplements without discussing with your cardiologist.

What dose of omega-3 do I need for triglyceride reduction?+

At least 2–4 g/day of combined EPA+DHA is required for meaningful triglyceride reduction. The 1 g/day in most OTC capsules has anti-inflammatory benefit but is insufficient to move triglycerides significantly. For aggressive triglyceride reduction, prescription icosapentaenoic acid at 4 g/day has the strongest evidence.

Can I take omega-3 with blood thinners?+

High-dose omega-3 above 3 g/day can increase bleeding risk when combined with warfarin, aspirin, or DOACs. At standard doses of 1–2 g/day the risk is minimal but should still be disclosed to your prescribing physician.

References

  1. Bhatt DL, et al. Cardiovascular risk reduction with icosapentaenoic acid (REDUCE-IT). N Engl J Med. 2019;380(1):11–22.
  2. Harris WS. N-3 fatty acids and serum lipoproteins: human studies. Am J Clin Nutr. 1997;65(5 Suppl):1645S–1654S.
Medical disclaimer

This guide is for educational purposes only and does not constitute medical advice. Always consult a qualified physician before starting any supplement, particularly if you are taking anticoagulants, statins, or other cardiovascular medications.

Medically reviewed by Dr. Regina Druz, MD, MBA, FACC, FMCP-M — Board-Certified Integrative Cardiologist at Holistic Heart Centers, Roslyn, NY. Last reviewed: May 2026.

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