Omega-3 fatty acids are essential nutrients that support heart, brain and visual health, yet your body cannot produce them independently. Understanding which foods provide these vital polyunsaturated fats—and how much you need—enables you to make informed dietary choices aligned with NHS guidance. Whether you consume fish, follow a plant-based diet, or have specific health considerations, accessible UK food sources can help you meet recommended intake levels. This evidence-based guide explores the best omega-3 food sources available in the UK, practical incorporation strategies, and tailored advice for different life stages and dietary patterns.

What Are Omega-3 Fatty Acids and Why Do You Need Them?

Omega-3 fatty acids are essential polyunsaturated fats that your body cannot produce independently, meaning they must be obtained through diet. These vital nutrients play important roles in maintaining health, including supporting heart, brain and visual function.

There are three main types of omega-3 fatty acids relevant to human nutrition: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is found primarily in plant sources and serves as a precursor that the body can convert to EPA and DHA, though this conversion is relatively inefficient (approximately 5-10% for EPA and less than 1% for DHA), with rates varying between individuals.

The health benefits of adequate omega-3 intake are supported by scientific research. According to the European Food Safety Authority (EFSA), EPA and DHA contribute to normal heart function at a daily intake of 250mg. DHA specifically contributes to the maintenance of normal brain function and vision. DHA is particularly important during pregnancy and early life for foetal and infant development. Omega-3 fatty acids also possess anti-inflammatory properties that may provide modest symptom relief in conditions such as rheumatoid arthritis, though they are not disease-modifying.

While true omega-3 deficiency is rare in the UK, ensuring adequate intake through dietary sources is an important component of a balanced, health-promoting diet for people of all ages. The NHS recommends regular consumption of foods rich in omega-3 fatty acids as part of a healthy, balanced diet.

Best Food Sources of Omega-3 in the UK

Oily fish represents the richest and most bioavailable source of EPA and DHA omega-3 fatty acids readily available in the UK. The NHS recommends consuming at least two portions of fish per week, including one portion (approximately 140g) of oily fish, as part of a healthy, balanced diet. The most accessible and beneficial options include:

• Salmon – both wild and farmed varieties provide excellent omega-3 content, with wild salmon typically containing slightly higher levels

• Mackerel – an affordable, sustainable option with very high omega-3 concentrations

• Sardines – convenient tinned varieties retain their omega-3 content and provide additional calcium from edible bones

• Herring – traditional British fish with substantial EPA and DHA levels

• Trout – particularly rainbow trout, widely available fresh or smoked

• Fresh tuna – note that tinned tuna is classified as non-oily fish by the NHS due to processing that reduces omega-3 content

A typical 100g portion of mackerel provides approximately 2-3g of combined EPA and DHA, whilst salmon offers around 1.5-2.5g, though values vary considerably by species, season, and farming method according to UK compositional data.

Shellfish and other seafood also contain omega-3 fatty acids, though generally in lower concentrations than oily fish. Mussels, oysters, and crab provide moderate amounts alongside other valuable nutrients including zinc, selenium, and vitamin B12.

When selecting fish, consider sustainability credentials. The Marine Conservation Society's Good Fish Guide provides UK-specific recommendations for environmentally responsible choices. Fresh, frozen, and tinned oily fish all retain beneficial omega-3 content, making them practical options for regular consumption.

Pregnant women should follow specific NHS guidance: limit oily fish to two portions weekly, limit tuna (fresh and tinned) to two tuna steaks or four medium-sized tins per week, and avoid shark, swordfish and marlin completely due to potential pollutant content. Pregnant women should also avoid raw shellfish and cod liver oil supplements (due to high vitamin A content) whilst ensuring adequate omega-3 intake for foetal development.

Plant-Based Omega-3 Sources for Vegetarians and Vegans

Individuals following vegetarian or vegan diets can obtain omega-3 fatty acids exclusively from plant sources, though these provide primarily ALA rather than the more readily utilised EPA and DHA forms. The body can convert ALA to EPA (approximately 5-10%) and DHA (less than 1%), with conversion rates varying between individuals based on genetics, age, sex, and overall diet composition.

Key plant-based omega-3 sources readily available in the UK include:

• Flaxseeds (linseeds) – a rich plant source, providing approximately 1.8-2.2g of ALA per tablespoon of ground seeds; bioavailability is improved by grinding, as whole seeds may pass through the digestive system largely undigested

• Chia seeds – contain around 1.7-1.9g of ALA per tablespoon and can be easily incorporated into porridge, smoothies, or baking

• Walnuts – a convenient snack providing approximately 2.5g of ALA per 30g serving (about seven whole walnuts)

• Hemp seeds – offer a balanced omega-3 to omega-6 ratio alongside complete protein

• Rapeseed oil – a UK-grown cooking oil containing meaningful ALA levels, suitable for everyday use

Other plant sources include edamame beans, Brussels sprouts, and leafy green vegetables such as spinach and kale, though these contain relatively modest amounts compared to seeds and nuts.

For vegans and vegetarians concerned about EPA and DHA intake, microalgae-derived supplements represent the only direct plant-based source of these fatty acids. Algae naturally produce EPA and DHA, which then accumulate in fish that consume them. Algal oil supplements are increasingly available in UK pharmacies and health food shops, providing a sustainable alternative to fish oil with typically lower risk of contaminants due to controlled manufacturing processes.

The British Dietetic Association recommends that vegans and vegetarians consume good sources of ALA daily and consider algal oil supplementation, particularly during pregnancy, breastfeeding, or if managing specific health conditions. Combining multiple plant sources throughout the day helps optimise overall omega-3 status.

How Much Omega-3 Do You Need Daily?

The UK does not have a specific Reference Nutrient Intake (RNI) for omega-3 fatty acids, but several authoritative bodies provide guidance on adequate intake levels. The Scientific Advisory Committee on Nutrition (SACN) and NHS recommendations focus on practical dietary patterns rather than precise numerical targets for the general population.

For adults, the NHS advises consuming at least two portions of fish per week, including one portion of oily fish (140g), which typically provides approximately 2-3g of combined EPA and DHA, though this varies considerably by fish species. This recommendation balances the cardiovascular benefits of omega-3 intake against potential risks from environmental contaminants that may accumulate in oily fish.

The European Food Safety Authority (EFSA) suggests that 250mg of combined EPA and DHA daily represents an adequate intake for maintaining normal heart function in healthy adults. For ALA, EFSA recommends approximately 0.5% of total energy intake, which equates to roughly 1-2g daily for most adults.

Specific populations have different requirements:

• Pregnant and breastfeeding women – EFSA recommends at least 200mg of DHA daily to support foetal and infant brain development. The NHS advises limiting oily fish to two portions weekly, limiting tuna consumption, avoiding shark/swordfish/marlin completely, and avoiding cod liver oil supplements due to high vitamin A content

• Children – the NHS recommends two portions of fish weekly (one oily) for children over 12 months, with portion sizes adjusted according to age

• Individuals with cardiovascular disease – NICE does not recommend routine omega-3 supplementation for primary or secondary prevention of cardiovascular disease. However, NICE Technology Appraisal 805 recommends icosapent ethyl (a purified EPA) for specific high-risk patients with elevated triglycerides despite statin therapy

EFSA has concluded that omega-3 intakes up to 5g of combined EPA and DHA daily are generally safe for adults. However, high-dose supplements may increase bleeding risk and interact with anticoagulant medications such as warfarin. If you are taking prescribed medications or have existing health conditions, consult your GP or pharmacist before significantly increasing omega-3 intake through supplements. Any suspected adverse reactions to omega-3 supplements or medicines can be reported to the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk).

Tips for Increasing Omega-3 in Your Diet

Incorporating adequate omega-3 fatty acids into your daily diet need not be complicated or expensive. The following practical strategies can help you achieve and maintain optimal intake using readily available UK food sources.

For fish consumers:

• Plan two fish meals weekly – aim for at least one oily fish portion; frozen fish is nutritionally equivalent to fresh and often more economical

• Keep tinned fish in your cupboard – sardines, mackerel, and salmon in spring water or olive oil provide convenient, long-life options for quick meals

• Try different preparations – grilled mackerel, smoked salmon on wholegrain toast, or sardines on jacket potatoes offer variety whilst maintaining nutritional benefits

• Add fish to familiar dishes – incorporate tinned salmon into pasta, fishcakes, or salads to increase consumption without dramatically changing eating patterns

For plant-based diets:

• Grind flaxseeds fresh – add to porridge, yoghurt, or smoothies; store whole seeds in the fridge and grind small amounts as needed

• Snack on walnuts – keep a small portion (approximately 30g) as a mid-morning or afternoon snack

• Use rapeseed oil for cooking – substitute for other vegetable oils in everyday cooking and salad dressings

• Sprinkle chia or hemp seeds – these versatile additions work well in breakfast cereals, baked goods, or as toppings for soups and salads

General dietary considerations:

Focus on increasing omega-3-rich foods rather than specifically reducing omega-6 sources. The NHS and British Nutrition Foundation emphasise that both omega-3 and omega-6 fatty acids are important components of a healthy diet, with the priority being to increase omega-3 intake for most people in the UK.

If considering supplementation, choose products from reputable UK brands that clearly state the EPA and DHA content per capsule and have evidence of contaminant testing. Speak with your community pharmacist about appropriate products, particularly if you are pregnant, breastfeeding, or taking medications. Remember that whole food sources provide additional nutrients beyond omega-3 fatty acids, including protein, vitamins, and minerals, making them preferable to supplements for most individuals. If you have concerns about meeting your omega-3 requirements through diet alone, your GP can provide personalised advice based on your individual health status and dietary preferences.

Frequently Asked Questions