Oily fish is the best-known source of omega-3, but plenty of people don't eat it. Some don't like the taste, some are vegetarian or vegan, and some simply never get round to it. Here's what UK guidance says about fish, the plant foods that contain omega-3, how the different types of omega-3 differ, and what to check if you're considering a supplement.
What does UK guidance say about fish?
The NHS says a healthy, balanced diet should include at least 2 portions of fish a week, including 1 of oily fish. A portion is around 140g. The NHS also says most of us are not eating this much.
Oily fish include:
- salmon
- sardines
- pilchards
- trout
- mackerel
- herring (including kippers)
- sprats
Fresh and canned tuna do not count as oily fish.
There are upper limits for some groups because oily fish can contain pollutants. The NHS advises girls and women who have not been through the menopause, including those trying for a baby, pregnant or breastfeeding, to have no more than 2 portions of oily fish a week.
The different types of omega-3
"Omega-3" is a family of fats, not a single nutrient:
- EPA and DHA are long-chain omega-3 fatty acids. The NHS describes oily fish as the richest source of long-chain omega-3. Some white fish and shellfish (oysters and crab in particular) contain smaller amounts.
- ALA (alpha-linolenic acid) is the omega-3 found in plant foods such as linseed, rapeseed oil, chia seeds and walnuts.
The European Food Safety Authority (EFSA) set separate reference values for these fats. For adults, it set an adequate intake of 250mg a day of EPA plus DHA combined, with a separate reference value for ALA.
Plant sources of omega-3
If you don't eat fish, the NHS suggests several foods. For vegetarians, the NHS lists:
- flaxseed (linseed) oil
- rapeseed oil
- walnuts
- eggs enriched with omega-3
For vegans, the NHS also lists:
- ground linseed (flaxseed) oil
- vegetable (rapeseed) oil
- chia seeds
- shelled hemp seeds
- walnuts
Simple ways to include them:
- use rapeseed oil for cooking and dressings
- sprinkle chia or hemp seeds on porridge or yoghurt
- add a handful of walnuts to salads or as a snack
- if you eat eggs, choose omega-3 enriched ones
Don't like oily fish? Small changes that help
If you eat fish but not "oily" fish, there are easy wins:
- Canned options: sardines, pilchards and tinned salmon are cheap and keep well. The NHS notes their edible bones also provide calcium and phosphorus.
- Milder choices: trout and salmon have a gentler taste than mackerel or herring.
- Hidden in meals: flake salmon into pasta or fishcakes, or mash sardines on toast with lemon and pepper.
- Shellfish: the NHS notes mussels, oysters, squid and crab provide some long-chain omega-3, though less than oily fish.
Do you need an omega-3 supplement?
UK guidance focuses on food: eat at least two portions of fish a week, including one oily. If you can't or don't want to eat oily fish, you might consider a supplement. If you do:
- Check what the label says per daily dose. Look for EPA and DHA amounts in milligrams, not just the total fish oil.
- Check suitability. Fish oil is not suitable for vegetarians or vegans, and capsules may be made with gelatine.
- Check allergies and medicines. If you have a fish or seafood allergy, or take anticoagulant (blood-thinning) medicines, speak to your GP or pharmacist first.
- Avoid cod liver oil in pregnancy. The NHS advises not taking cod liver oil or supplements containing vitamin A (retinol) when pregnant.
Dr Marks Omega 3
Our Omega 3 Fish Oil is a concentrated fish oil (33% EPA / 22% DHA; 330mg EPA and 220mg DHA per capsule) with added vitamin E to help protect the oil from oxidation. It's formulated by GPs. The directions are two capsules daily with food. Please note:
- the oil comes from fish and the capsule shell is fish gelatine, so it is not suitable for vegetarians or vegans
- it contains fish, so avoid it if you have a fish allergy
- if you take anticoagulant medication, check with your GP or pharmacist before use
Each capsule provides 330mg of EPA and 220mg of DHA, so the recommended two capsules a day provide 660mg of EPA and 440mg of DHA. EPA and DHA contribute to the normal function of the heart. The beneficial effect is obtained with a daily intake of 250mg of EPA and DHA.
Frequently asked questions
How can I get omega-3 without eating fish?
The NHS lists flaxseed (linseed) oil, rapeseed oil, chia seeds, shelled hemp seeds and walnuts as plant sources, plus omega-3 enriched eggs for vegetarians. These provide mainly ALA, a different omega-3 from the EPA and DHA in oily fish.
How much omega-3 do I need a day?
UK guidance is food-based: at least two portions of fish a week, one of them oily. EFSA set an adequate intake of 250mg a day of EPA plus DHA for adults.
Does tuna count as oily fish?
No. The NHS says fresh and canned tuna do not count as oily fish.
Is fish oil suitable for vegetarians?
No. Fish oil comes from fish and is often in gelatine capsules. Our Omega 3 uses a fish-gelatine capsule and is not suitable for vegetarians or vegans.
Can I take omega-3 when pregnant?
Speak to your midwife, GP or pharmacist first. The NHS advises avoiding cod liver oil and vitamin A (retinol) supplements in pregnancy, and limiting oily fish to two portions a week.
References
- NHS. Fish and shellfish. https://www.nhs.uk/live-well/eat-well/food-types/fish-and-shellfish-nutrition/ (accessed 14 October 2026)
- NHS. Fat: the facts (different fats). https://www.nhs.uk/live-well/eat-well/food-types/different-fats-nutrition/ (accessed 14 October 2026)
- NHS. The vegan diet. https://www.nhs.uk/live-well/eat-well/how-to-eat-a-balanced-diet/the-vegan-diet/ (accessed 14 October 2026)
- NHS. Pregnancy vitamins and supplements. https://www.nhs.uk/pregnancy/keeping-well/pregnancy-vitamins-and-supplements/ (accessed 14 October 2026)
- EFSA Panel on Dietetic Products, Nutrition and Allergies (2010). Scientific Opinion on Dietary Reference Values for fats. EFSA Journal 8(3):1461. https://www.efsa.europa.eu/en/efsajournal/pub/1461 (accessed 14 October 2026)
Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle. Do not exceed the stated daily dose. Keep out of reach of children. If you are pregnant, breastfeeding, taking any medication (including blood thinners), have a fish or seafood allergy, or are under medical supervision, speak to your GP or pharmacist before taking supplements. This article is general information and is not a substitute for personal medical advice. Dr Marks is not affiliated with or endorsed by the NHS.
Medically reviewed by Dr Mark Wilshere, MBChB, MRCGP (2013), DCH, BSc (Hons), GP
