How to get omega-3 is a common question for those seeking to support cardiovascular health, brain function, and inflammatory balance. Omega-3 fatty acids—including alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA)—are essential nutrients that the body cannot produce efficiently. The NHS recommends obtaining omega-3 primarily through diet, particularly from oily fish such as salmon, mackerel, and sardines. Plant-based sources like flaxseeds and walnuts provide ALA, though conversion to EPA and DHA is limited. Understanding the different types of omega-3, their food sources, and when supplementation may be appropriate enables informed dietary choices aligned with UK guidance.

What Is Omega-3 and Why Do You Need It?

Omega-3 fatty acids are a family of polyunsaturated fats that play important roles in human health. Of these, alpha-linolenic acid (ALA) is essential, meaning the body cannot produce it and must obtain it from diet. The long-chain omega-3s—eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)—can be synthesised from ALA, but conversion rates are relatively low (typically less than 10% for EPA and even lower for DHA), so obtaining them directly from diet is beneficial.

These fatty acids contribute to maintaining cardiovascular health, supporting brain function, and modulating inflammatory responses throughout the body. DHA is an important structural component of the brain and retina, while EPA contributes to the production of signalling molecules called eicosanoids, which help regulate inflammation, blood clotting, and immune function.

Evidence from observational studies and clinical trials suggests that adequate omega-3 intake, particularly through consumption of oily fish, is associated with various health benefits. The NHS recommends including fish, especially oily fish, as part of a balanced diet. NICE guidance on cardiovascular disease recommends a Mediterranean-style diet that includes fish, though it does not recommend omega-3 supplements for cardiovascular disease prevention.

Whilst omega-3 fatty acids are important for health, it is best to obtain these nutrients through evidence-based approaches rather than relying on unsubstantiated health claims. Understanding the different types of omega-3 and their sources enables informed dietary choices.

Food Sources Rich in Omega-3 Fatty Acids

The most concentrated dietary sources of EPA and DHA are oily fish, which the NHS recommends consuming as part of a healthy, balanced diet. The recommendation is to eat at least two portions of fish per week, including one portion of oily fish. Fish particularly rich in omega-3 include:

• Salmon (wild and farmed varieties)

• Mackerel

• Sardines

• Herring

• Pilchards

• Fresh tuna (though canned tuna contains significantly less omega-3 due to processing and is not counted as oily fish in NHS guidance)

• Trout

A typical 140g portion of oily fish provides varying amounts of combined EPA and DHA, with levels differing by species, season, and whether the fish is wild-caught or farmed. Smaller oily fish such as sardines and anchovies tend to have lower levels of environmental contaminants whilst still providing substantial omega-3 content.

For those following plant-based diets, ALA can be obtained from several sources, though it is important to note that conversion to EPA and DHA is limited. Rich plant sources include:

• Flaxseeds (linseeds) and flaxseed oil

• Chia seeds

• Walnuts

• Hemp seeds

• Rapeseed oil

• Soya beans and soya products

Some foods are now fortified with omega-3, including certain eggs (from hens fed omega-3-enriched diets), spreads, yoghurts, and milk alternatives. Whilst these can contribute to overall intake, they typically provide smaller amounts compared to oily fish or concentrated plant sources.

Algal oil, derived from marine algae, represents a vegetarian and vegan source of preformed DHA and sometimes EPA, offering an alternative to fish-based omega-3 for those who avoid animal products.

How Much Omega-3 Should You Take Daily?

There is no single universally agreed recommendation for omega-3 intake in the UK, as requirements may vary based on individual health status, age, and dietary patterns. The NHS and Scientific Advisory Committee on Nutrition (SACN) focus on food-based guidance rather than specific nutrient targets for EPA and DHA.

The NHS recommends eating at least two portions of fish per week, including one portion of oily fish. This is estimated to provide approximately 450mg of combined EPA and DHA daily when averaged across the week, according to the British Dietetic Association. For ALA, the UK reference nutrient intake is approximately 0.2% of total energy intake.

Pregnant and breastfeeding women have specific guidance regarding fish consumption. The Food Standards Agency (FSA) advises that pregnant women, those trying to conceive, and breastfeeding mothers can eat up to two portions of oily fish weekly. They should avoid shark, swordfish, and marlin completely due to mercury content, and limit tuna to no more than two fresh tuna steaks or four medium-sized cans per week. If fish consumption is limited, supplementation may be considered under medical guidance.

It is worth noting that excessive omega-3 intake—particularly from supplements—may increase bleeding risk and potentially interact with anticoagulant medications. Patients taking warfarin who start or stop omega-3 supplements should have their INR monitored. The European Food Safety Authority (EFSA) considers supplemental intakes up to 5g daily of combined EPA and DHA to be safe for the general adult population, though such high doses should only be taken under medical supervision.

Individuals taking omega-3 supplements should inform their GP or pharmacist, particularly if they are on antiplatelet or anticoagulant therapy, or scheduled for surgery. Any suspected side effects from omega-3 medicines or supplements can be reported through the MHRA Yellow Card Scheme.

Who May Benefit from Omega-3 Supplementation?

Whilst dietary sources remain the preferred method of obtaining omega-3 fatty acids, certain groups may benefit from supplementation when dietary intake is insufficient or specific health conditions warrant additional support.

Individuals who do not consume oily fish represent the primary group who may require supplementation. This includes vegetarians, vegans, and those with fish allergies or aversions. For plant-based eaters, algal oil supplements provide a direct source of DHA and EPA without relying on the inefficient conversion from ALA.

For cardiovascular disease, it's important to note that NICE does not recommend omega-3 supplements for routine primary or secondary prevention. However, a specific prescription-only omega-3 product (icosapent ethyl) is recommended by NICE (TA805) for reducing cardiovascular risk in certain high-risk patients with elevated triglycerides who are already taking statins. This should only be prescribed by specialists and differs from over-the-counter fish oil supplements.

Prescription omega-3 medicines (containing 2–4g of EPA and DHA) may be used under specialist supervision for treating hypertriglyceridaemia, in line with their licensed indications. These are different from food supplements and require medical oversight.

Pregnant and breastfeeding women who cannot meet omega-3 requirements through diet alone may benefit from supplementation, particularly for DHA. However, supplements should be specifically formulated for pregnancy, avoiding high vitamin A content found in some fish liver oils, as excessive vitamin A can be harmful during pregnancy.

Some patients with inflammatory conditions such as rheumatoid arthritis report symptomatic improvement with omega-3, though evidence quality varies. Any supplementation should complement rather than replace conventional disease-modifying treatments and should be discussed with healthcare professionals.

Before starting any omega-3 supplement, individuals should consult their GP or pharmacist, particularly if they have bleeding disorders, take anticoagulant medications, or have upcoming surgical procedures. Quality varies significantly between products, and those meeting pharmaceutical standards or carrying quality assurance marks are preferable. Food supplements are regulated differently from medicines and cannot make medicinal claims about treating or preventing disease.

Frequently Asked Questions