Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are essential omega-3 fatty acids that support cardiovascular health, brain function, and inflammatory regulation. In the UK, the Scientific Advisory Committee on Nutrition recommends approximately 450 mg of combined EPA and DHA daily for adults, typically achieved through consuming at least two portions of fish weekly, including one portion of oily fish. Understanding how much EPA and DHA per day you need depends on age, health status, and dietary habits. This article explores evidence-based recommendations, food sources, supplementation options, and safety considerations to help you maintain optimal omega-3 intake.

What Are EPA and DHA Omega-3 Fatty Acids?

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are long-chain omega-3 polyunsaturated fatty acids important for human health. These fatty acids are not efficiently synthesised by the body and are primarily obtained through diet or supplementation. EPA and DHA are mainly found in marine sources, particularly oily fish, and play distinct yet complementary roles in maintaining physiological function.

EPA is a 20-carbon fatty acid that serves as a precursor to eicosanoids—signalling molecules involved in regulating inflammation, immune response, and cardiovascular function. It is particularly recognised for its anti-inflammatory properties and potential benefits in mood regulation. DHA, a 22-carbon fatty acid, is the most abundant omega-3 in the brain and retina, where it contributes to neuronal membrane fluidity, synaptic plasticity, and visual function. During pregnancy and early childhood, DHA is important for foetal and infant neurodevelopment.

Whilst the body can convert alpha-linolenic acid (ALA), a plant-based omega-3 found in flaxseeds and walnuts, into EPA and DHA, this conversion is highly inefficient—typically less than 5-10% for EPA and even lower for DHA. Consequently, direct dietary intake of EPA and DHA from marine sources or supplements is the most effective way to achieve adequate levels. Understanding the distinct functions of these fatty acids helps clarify why specific intake recommendations exist and why they are considered important components of a balanced diet for cardiovascular health maintenance.

Recommended Daily Intake of EPA and DHA in the UK

In the UK, there is no single universally mandated daily requirement for EPA and DHA. The Scientific Advisory Committee on Nutrition (SACN) suggests that adults consume approximately 450 mg of combined EPA and DHA per day, which is derived from the NHS recommendation to eat at least 2 portions of fish per week, including 1 portion of oily fish (about 140g per portion).

The European Food Safety Authority (EFSA) suggests that 250 mg of combined EPA and DHA daily is adequate for general cardiovascular maintenance in healthy adults. For pregnant and breastfeeding women, EFSA recommends an additional 100–200 mg of DHA per day to support foetal brain and eye development.

The NHS advises consuming at least 2 portions of fish per week, including 1 portion of oily fish, which typically provides approximately 2–3 g of omega-3 fatty acids, including EPA and DHA. Pregnant women should limit oily fish to 2 portions per week due to potential pollutant concerns.

It is important to note that the UK National Institute for Health and Care Excellence (NICE) does not recommend routine omega-3 supplements for cardiovascular disease prevention. However, for specific high-risk patients with elevated triglycerides, prescription icosapent ethyl (a highly purified EPA) may be recommended by specialists at a dose of 2g twice daily.

These recommendations reflect general population guidance; individual requirements may vary based on age, health status, pregnancy, and existing medical conditions. Those unable to consume fish regularly due to dietary preferences, allergies, or sustainability concerns should consider alternative sources to ensure adequate omega-3 status for long-term health.

Health Benefits of EPA and DHA Supplementation

Cardiovascular health has been extensively researched in relation to EPA and DHA. These omega-3 fatty acids may help reduce triglyceride levels, lower blood pressure modestly, decrease platelet aggregation, and improve endothelial function. Epidemiological studies show that populations with higher fish consumption have lower rates of coronary heart disease. However, it's important to note that NICE does not recommend routine omega-3 supplements for cardiovascular disease prevention. Prescription omega-3 preparations containing high-dose EPA and DHA are licensed in the UK for managing endogenous hypertriglyceridaemia under medical supervision.

Cognitive and mental health effects continue to be studied. DHA is integral to brain structure and function throughout life. Adequate DHA intake during pregnancy and infancy supports neurodevelopment. In adults, the evidence for omega-3 supplementation in maintaining cognitive function with ageing is mixed and inconclusive. Some studies suggest EPA may have a role in managing symptoms of mild to moderate depression, though NICE does not recommend omega-3 supplements as a treatment for depression, and they should not replace conventional treatment.

Anti-inflammatory effects extend beyond the cardiovascular and nervous systems. EPA and DHA influence the production of pro-inflammatory and anti-inflammatory mediators, potentially offering symptomatic benefits in conditions characterised by chronic inflammation, such as rheumatoid arthritis. Some patients report reduced joint stiffness and pain with regular omega-3 supplementation as an adjunct to conventional treatment, though responses vary individually.

Eye health is supported primarily by DHA, which comprises a significant proportion of retinal photoreceptor membranes. While some observational studies suggest a relationship between omega-3 intake and age-related macular degeneration (AMD), clinical trials have not consistently demonstrated preventative benefits, and NICE does not currently recommend omega-3 supplements for AMD prevention or treatment.

Whilst omega-3 supplementation offers potential benefits, it should complement, not replace, a balanced diet and evidence-based medical treatment for specific conditions.

Food Sources and Supplements: Meeting Your Daily EPA and DHA Needs

Oily fish remains the richest and most bioavailable source of EPA and DHA. The NHS recommends consuming at least 2 portions of fish per week, including 1 portion of oily fish (approximately 140 g). Excellent sources include:

• Salmon (wild or farmed): ~2–2.5 g EPA+DHA per 100 g

• Mackerel: ~2.5–3 g per 100 g

• Sardines: ~1.5–2 g per 100 g

• Herring: ~2 g per 100 g

• Trout: ~1–1.5 g per 100 g

• Fresh tuna (not canned): ~1–1.5 g per 100 g

It is worth noting that canned tuna contains significantly lower omega-3 levels due to processing. Pregnant women should follow NHS guidance by avoiding shark, swordfish, and marlin due to mercury content; limiting fresh tuna to 2 steaks weekly or 4 medium-sized cans weekly; and consuming no more than 2 portions of oily fish per week.

Omega-3 supplements are a practical alternative for those who do not consume fish regularly. Available forms include:

• Fish oil capsules: Most common; check EPA and DHA content per serving

• Cod liver oil: Contains EPA and DHA plus vitamins A and D (avoid excessive vitamin A during pregnancy)

• Krill oil: Contains EPA and DHA in phospholipid form

• Algal oil: Vegetarian/vegan source derived from microalgae; primarily provides DHA, with some products now including EPA

When selecting supplements, look for products that clearly state EPA and DHA content rather than just total omega-3. Quality assurance is important—choose supplements from reputable UK suppliers to ensure purity and absence of contaminants such as heavy metals. Supplements should be stored properly (cool, dark place) to prevent oxidation, which can reduce efficacy and create an unpleasant taste.

Safety Considerations and Maximum Dosage Limits

EPA and DHA supplementation is generally well tolerated at recommended doses, but several safety considerations warrant attention. The EFSA has concluded that combined EPA and DHA intakes up to 5 g per day from supplements do not raise safety concerns for the general adult population. However, most individuals do not require such high doses, and routine supplementation typically involves 250–1,000 mg daily.

Common adverse effects at standard doses are usually mild and include:

• Fishy aftertaste or burping (can be minimised by taking with meals or using enteric-coated capsules)

• Mild gastrointestinal upset, including nausea or loose stools

• Fishy body odour (rare)

Bleeding risk is a theoretical concern at very high doses (above 3 g daily) because omega-3 fatty acids have antiplatelet effects. However, clinically significant bleeding is uncommon. Nonetheless, individuals taking anticoagulant medications (warfarin, DOACs) or antiplatelet agents (aspirin, clopidogrel) should consult their GP or pharmacist before starting high-dose omega-3 supplements, as monitoring may be advisable.

Atrial fibrillation risk has been observed with high-dose omega-3 supplementation, particularly with prescription products. If you experience palpitations while taking omega-3 supplements, seek medical advice.

Drug interactions are generally limited, but omega-3 supplements may modestly enhance the effects of blood pressure medications. Patients on antihypertensive therapy should inform their healthcare provider if starting supplementation.

Pregnancy and breastfeeding: Omega-3 supplementation is considered safe and beneficial during pregnancy, particularly for DHA. However, pregnant women should avoid cod liver oil due to high vitamin A content, which can be harmful in excess. Algal oil or pregnancy-specific omega-3 supplements are safer alternatives.

When to seek medical advice: Contact your GP if you experience persistent gastrointestinal symptoms, unusual bleeding or bruising, palpitations, or allergic reactions (rare). Always inform healthcare professionals about supplement use, especially before surgery. Individuals with fish or shellfish allergies should exercise caution and may prefer algal-derived supplements.

Report any suspected side effects to the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk or via the Yellow Card app).

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