Omega 3 Fatty Acids in Dyslipidaemia

Omega 3 fatty acids, mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), lower triglycerides by reducing hepatic VLDL production and increasing triglyceride clearance. At prescription doses (about 4 g daily) they reduce triglycerides by 20% to 30%, and up to 45% in severe hypertriglyceridaemia. A pure EPA product reduced cardiovascular events in high-risk patients with raised triglycerides on statins, while mixed EPA and DHA products have not shown consistent event reduction.

Members. Icosapent ethyl (pure EPA), omega 3 acid ethyl esters (EPA with DHA), omega 3 carboxylic acids, and non-prescription fish oil capsules (low dose, variable content).

Mechanism. Reduced hepatic synthesis of triglyceride and apolipoprotein B, increased beta oxidation, and increased lipoprotein lipase activity. EPA also has anti-inflammatory and membrane-stabilising effects that may contribute to benefit.

Pharmacokinetics. Absorption improves when taken with a meal containing fat. Effects on triglycerides appear within 2 to 4 weeks.

• Icosapent ethyl: pure EPA 4 g daily; does not raise LDL cholesterol; evidence for event reduction.
• Omega 3 ethyl esters (EPA plus DHA): 4 g daily for severe hypertriglyceridaemia; DHA can raise LDL cholesterol.
• Over-the-counter fish oil: low dose (under 1 g EPA plus DHA); no demonstrated benefit for lipids or events.

• Severe hypertriglyceridaemia (5.7 mmol/L or over, 500 mg/dL): omega 3 ethyl esters 4 g daily (2 g twice daily, or 4 g once daily with food), alongside diet, alcohol restriction, glucose control and a fibrate if over 10 mmol/L.
• Established atherosclerotic disease or diabetes with other risk factors, on a statin, with triglycerides 1.5 to 5.6 mmol/L: icosapent ethyl 2 g twice daily with meals to reduce cardiovascular events.
• Diet: eating oily fish twice weekly (for example omena, sardines, mackerel, tilapia) is advised for heart health and is not a substitute for drug therapy.
• Selection: add after statin therapy, not as first-line treatment, and do not use supplements to lower cardiovascular risk.

Contraindications. Known hypersensitivity to fish or shellfish products (caution), and hypersensitivity to ingredients. Use with caution in bleeding disorders.

Adverse effects. Eructation and fishy taste, gastrointestinal upset, diarrhoea, increased atrial fibrillation (about 25% to 35% relative rise at 4 g daily in high-risk patients), small increase in minor bleeding, raised LDL cholesterol (DHA-containing products), and raised liver enzymes.

Interactions. Anticoagulants and antiplatelet drugs add a small bleeding risk, with no routine INR change at usual doses. Antihypertensive drugs may add to blood pressure lowering.

Monitoring. Triglycerides and LDL cholesterol at 4 to 8 weeks, liver enzymes in prolonged use, and heart rhythm or symptoms of palpitations. Review the need for therapy at 3 to 6 months.

Referral and escalation. Triglycerides over 10 mmol/L, abdominal pain or pancreatitis, and new atrial fibrillation need prompt review.

Special groups. Pregnancy: dietary intake is safe, and prescription doses need specialist advice. Atrial fibrillation: avoid or use with caution. Older adults: no dose change. Children: specialist use only.