Omega-3 triglycerides (EPA and DHA)

Lipid-modifying agents. Omega-3 polyunsaturated fatty acids

ATC code: C10AX06 (Omega-3 triglycerides incl. other esters and acids)

Brand names – drugs

Vascepa, Lovaza

Brand names – supplements

Nordic Naturals Ultimate Omega, Carlson Elite Omega-3, NOW Foods Ultra Omega-3

Supplements are not tested in clinical trials and are not registered as medications.

Mechanism of action

Eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids reduce hepatic triglyceride synthesis by inhibiting acyl-CoA carboxylase and stimulating fatty acid β-oxidation. They decrease VLDL secretion and enhance chylomicron clearance. Additional effects include cardiomyocyte membrane stabilisation, antiarrhythmic action, and anti-inflammatory effects via reduced pro-inflammatory eicosanoid synthesis.

Indications

Severe hypertriglyceridaemia

First line

High-dose omega-3 PUFA (2–4 g EPA+DHA daily) reduces triglycerides by 20–50% in patients with severe hypertriglyceridaemia. The 2019 AHA Science Advisory lists high-dose omega-3 as a first-line option when triglycerides exceed 500 mg/dL (5.6 mmol/L) to reduce acute pancreatitis risk. Omacor and similar products with at least 84% EPA+DHA content are registered for this indication.

Over-the-counter supplements with lower EPA+DHA content are not used for this indication – the therapeutic dose would require 6–8 capsules of standard fish oil daily, which is impractical.

Sources

Secondary cardiovascular prevention on statin therapy

Individual decision

Evidence is conflicting. REDUCE-IT (NEJM 2019, 8,179 patients) showed a 25% reduction in major cardiovascular events with icosapent ethyl 4 g daily in statin-treated patients with triglycerides 150–500 mg/dL. However, STRENGTH (JAMA 2020, 13,078 patients) with a similar design but a different formulation (EPA+DHA) showed no benefit. The role of the mineral oil placebo in REDUCE-IT is debated. In both trials and in OMEMI (Circulation 2021), high-dose omega-3 therapy increased atrial fibrillation incidence by 30–70% depending on formulation. A meta-analysis of 5 large RCTs (Circulation 2021, Lombardi et al.) confirmed a dose-dependent atrial fibrillation risk. ESC 2021 includes icosapent ethyl for a narrow patient group with residual hypertriglyceridaemia. EPA+DHA mixtures (Omacor) are not indicated for cardiovascular risk reduction when triglycerides are normal.

In patients on maximally tolerated statins with residual hypertriglyceridaemia, icosapent ethyl is considered – not over-the-counter fish oil. Baseline cardiac rhythm and history of atrial fibrillation are assessed before prescribing.

Sources

Primary cardiovascular prevention in individuals without established CVD

Not recommended

In adults without established CVD, omega-3 PUFA capsules do not reduce cardiovascular or all-cause mortality. The 2020 Cochrane review (86 RCTs, more than 162,000 participants) found no clinically meaningful effect. The OMEMI trial (Circulation 2021) in older adults after myocardial infarction also showed no MACE reduction and increased atrial fibrillation. ESC 2021 does not recommend omega-3 for primary prevention. An evidence-based exception is the JELIS trial (Lancet 2007) in a Japanese population with high baseline fish intake: adding EPA 1.8 g daily to statins reduced MACE by 19%. This effect has not been reproduced in populations with low baseline fish intake. Over-the-counter supplements with 300–500 mg EPA+DHA per capsule do not affect cardiovascular risk and can increase atrial fibrillation risk with long-term high-dose use.

Fatty marine fish in the diet (2 servings per week) remains the baseline recommendation by the AHA and ESC. Dietary omega-3 is the only form with robust evidence for reduced CVD mortality in healthy adults. Fish versus capsules is a comparison with fundamentally different evidence strength.

Sources

Anti-aging and longevity (marketed indication)

Not recommended

The VITAL-ancillary RCT (BMJ 2022) tested the combination of omega-3 1 g daily and vitamin D and found no significant effect on all-cause mortality or biological age markers. International guidelines do not recommend omega-3 for slowing ageing. For anti-ageing use, omega-3 is not recommended in healthy individuals.

Sources

NEJM: Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease (VITAL trial) (2019)

Practical notes

Timing and administration

Take with a meal, preferably one containing fat – absorption increases 2–3 fold compared with an empty stomach. Enteric-coated capsules (icosapent ethyl) can be taken at any time of day.

Dose titration

For hypertriglyceridaemia treatment – 2–4 g EPA+DHA daily (4 capsules of Omacor 1,000 mg daily or 4 capsules of Vascepa 1,000 mg daily). For cardiovascular prevention in statin-treated patients with hypertriglyceridaemia – 4 g daily. Doses below 1 g daily are ineffective for hypertriglyceridaemia treatment.

Monitoring

Check triglycerides 6–8 weeks after starting therapy. If the target is not reached, reassess lifestyle, concomitant therapy, and secondary causes. Monitor liver function (ALT, AST) during long-term therapy – high-dose omega-3 rarely elevates transaminases.

Food and drinks

Dietary fish and capsules are approaches with fundamentally different evidence strength. Regular fatty marine fish intake (mackerel, sardines, herring, salmon) 2 servings weekly reliably reduces cardiovascular mortality – confirmed by large cohort studies and the 2018 AHA Science Advisory. Fish oil capsules at comparable doses in healthy adults have not shown an effect on CVD mortality (Cochrane 2020, VITAL 2019, OMEMI 2021). The single exception is the 2007 Japanese JELIS RCT with EPA 1.8 g daily on top of high baseline fish intake. On anticoagulant or antiplatelet therapy, bleeding risk with capsule doses above 3 g daily increases – requires discussion with the treating clinician.

Special situations

The risk of atrial fibrillation with long-term high-dose omega-3 (2–4 g daily) increases in a dose-dependent fashion. REDUCE-IT (3.1% vs 2.1% on placebo), STRENGTH (2.2% vs 1.3%), OMEMI, and the 2021 meta-analysis confirmed the effect. Before prescribing high-dose therapy, a cardiology discussion is warranted in patients with prior paroxysmal atrial fibrillation, structural heart disease, or an established pacemaker. If rapid or irregular palpitations develop during therapy, an ECG and reassessment of continued use are indicated.

Common myths

Myth: “capsule omega-3 is good for everyone's heart”. Fact: in healthy people with normal triglycerides, capsules do not reduce cardiovascular risk. The 2020 Cochrane review (162,000 participants) and VITAL 2019 confirmed this. Benefit is demonstrated only in narrow groups: severe hypertriglyceridaemia and statin-treated patients with residual hypertriglyceridaemia (icosapent ethyl).

Myth: “fish oil and dietary fatty fish work the same”. Fact: large observational studies (Mozaffarian & Rimm JAMA 2006, 2018 AHA Advisory) show that regular fatty fish intake of 2 servings weekly reduces CVD mortality. Capsule fish oil at equivalent doses in healthy adults has not shown this effect. The single exception is the 2007 Japanese JELIS trial in patients with high baseline fish intake.

Myth: “omega-3 has no side effects”. Fact: high-dose therapy (2–4 g daily) increases atrial fibrillation risk in a dose-dependent manner. REDUCE-IT, STRENGTH, OMEMI, and the 2021 Circulation meta-analysis documented a 30–70% increase in atrial fibrillation incidence.

Myth: “omega-3 improves cognition and prevents dementia”. Fact: systematic reviews have not confirmed an effect in adults without dementia. Some paediatric society recommendations address DHA in infants under 2 years – but not in adults.

Myth: “fish oil and Omacor are the same”. Fact: Omacor contains 84% EPA+DHA as ethyl esters and is registered as a medicine. Mass-market fish oil contains 18–30% EPA+DHA and is registered as a supplement. A therapeutic 4 g EPA+DHA dose requires 4 capsules of Omacor or 12–15 capsules of a supplement.

Safety

Contraindications

Hypersensitivity to fish or seafood components
Haemorrhagic diathesis, haemophilia
Active clinically significant bleeding
Age under 18 months for drug formulations

Serious adverse effects

Dose-dependent increase in atrial fibrillation with long-term high-dose use (2–4 g daily): REDUCE-IT 3.1% vs 2.1% on placebo, STRENGTH 2.2% vs 1.3%, OMEMI 2021 and the Lombardi et al. Circulation 2021 meta-analysis confirmed the effect. Risk is higher in patients with structural heart disease and prior paroxysmal atrial fibrillation
Prolonged bleeding time when combined with anticoagulants and antiplatelets; clinically significant bleeding reported at doses above 3 g daily
Hypersensitivity reactions in patients with fish allergy

Common adverse effects

Dyspepsia, fish-flavoured eructation
Nausea, epigastric discomfort
Flatulence

Uncommon adverse effects

Increased bleeding time at high doses
10–15% LDL increase in some patients
Elevated liver transaminases

PregnancyFDA C

Controlled pregnancy data are limited. Dietary omega-3 sources are encouraged in pregnancy by ACOG. High-dose pharmaceutical forms for hypertriglyceridaemia treatment are used only when clearly indicated.

Breastfeeding

Transfers into breast milk. Breast milk DHA supports infant brain development. Supplementation during breastfeeding is acceptable at supplement-level doses (up to 1 g daily) without special precautions.