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Most people in the UK can get enough omega-3 from food by following the NHS advice to eat at least two portions of fish a week, one of which should be oily, such as salmon, mackerel, sardines or herring. The trouble is that many adults eat far less fish than that. If oily fish rarely appears on your plate, it is worth looking at other sources and, as a second step, at a supplement.
This article explains the different types of omega-3, how much you need, who tends to fall short and what to check if you choose a fish oil supplement.
In short
- Omega-3 fatty acids are fats that the body needs but cannot make in sufficient amounts on its own.
- EPA and DHA come mainly from oily fish, while ALA comes from plant foods such as linseed, walnuts and rapeseed oil.
- The NHS recommends at least two portions of fish a week, including one portion of oily fish.
- EPA and DHA contribute to the normal function of the heart; the beneficial effect is obtained with a daily intake of 250 mg of EPA and DHA.
- EFSA considers combined intakes of EPA and DHA of up to 5 g a day from supplements to be safe for adults.
What are omega-3 fatty acids?
Omega-3 fatty acids are a family of polyunsaturated fats. The three you will see most often on labels are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA is an essential fatty acid, which means your body cannot make it and has to get it from food.
The body can convert some ALA into EPA and, to a lesser degree, into DHA, but the conversion rate is low. This is why nutrition advice focuses on getting EPA and DHA directly, mainly from fish and seafood.
Where does omega-3 come from in food?
The richest sources of EPA and DHA are oily fish. White fish and shellfish contain smaller amounts. Plant foods provide ALA instead, which is useful but not a direct replacement for EPA and DHA.
| Food | Main type of omega-3 | How to include it |
|---|---|---|
| Salmon, mackerel, sardines, herring, pilchards, trout | EPA and DHA | One portion a week, fresh, frozen or tinned |
| Cod, haddock, plaice, prawns | Small amounts of EPA and DHA | As your second weekly fish portion |
| Linseed (flaxseed) and chia seeds | ALA | Sprinkled on porridge or yoghurt |
| Walnuts | ALA | A small handful as a snack |
| Rapeseed oil | ALA | For cooking and salad dressings |
| Omega-3 enriched eggs | Small amounts, depending on the hens’ feed | Check the label for the amount per egg |
Tinned fish counts towards your weekly portions, which makes it an easy option. Tinned tuna, however, is not classed as oily fish in UK advice, because the canning process removes much of its oil.
How much omega-3 do you need?
The UK does not set an official daily target in milligrams for the general public. Instead, the NHS gives food-based advice: at least two portions of fish a week, one of them oily, with a portion being about 140 g once cooked. For most adults this provides a reasonable amount of EPA and DHA.
At EU level, the European Food Safety Authority (EFSA) has looked at the numbers. In its 2012 assessment, EFSA explained that the normal function of the heart requires about 250 mg of EPA and DHA a day, and that average intakes among adults in Europe are around 400 to 500 mg a day, while the highest consumers reach about 2,700 mg. People who rarely eat oily fish are likely to sit well below the average. EFSA also concluded that supplemental intakes of EPA and DHA combined of up to 5 g a day do not raise safety concerns for adults.
Who often falls short?
You may not be getting enough EPA and DHA if any of the following apply to you. You rarely or never eat oily fish, perhaps because you dislike the taste or the smell when cooking. You follow a vegetarian or vegan diet, which provides ALA but very little EPA or DHA. You eat mostly white fish or fish fingers rather than oily fish. Or your meals are often rushed and built around convenience food.
If you do not eat fish for ethical reasons, our guide to vegetarian omega-3 covers plant sources and algae-based options in more detail.
Is there any reason to limit oily fish?
Oily fish can contain low levels of pollutants, so the NHS suggests some limits. Girls and women who are pregnant, planning a pregnancy or breastfeeding are advised to eat no more than two portions of oily fish a week. Pregnant women should also avoid shark, swordfish and marlin, and limit tuna. Other adults can safely eat more oily fish, up to around four portions a week.
These limits do not mean you should avoid fish. They simply help you balance the benefits of fish with the small amounts of contaminants it may carry.
Should you take an omega-3 supplement?
Food comes first. A supplement makes sense mainly when your diet regularly falls short and you cannot or do not want to change it, for example if you never eat oily fish. In that case, a fish oil capsule is a simple way to add EPA and DHA to your week.
When you compare products, look at the amount of EPA and DHA per daily dose, not only the total amount of fish oil. A capsule with 1,000 mg of fish oil might contain only a third of that as EPA and DHA.
LR’s Super Omega capsules provide 630 mg of EPA and 420 mg of DHA in the daily dose of three capsules, which is 1,050 mg of EPA and DHA in total. EPA and DHA contribute to the normal function of the heart; the beneficial effect is obtained with a daily intake of 250 mg of EPA and DHA. DHA also contributes to the maintenance of normal brain function and to the maintenance of normal vision; these beneficial effects are obtained with a daily intake of 250 mg of DHA. The capsules also contain evening primrose oil and barley extract. You can find other supplements in our supplements category.
For a closer look at different oils, forms and what to check on a label, read our article on fish oil.
When should you see a doctor?
Omega-3 supplements are well tolerated by most people, but some situations call for advice before you start. Speak to your GP or pharmacist if you take blood-thinning medicines such as warfarin or other anticoagulants, if you have a fish or shellfish allergy, if you have a planned operation, or if you are pregnant or breastfeeding. You should also see your GP if you have symptoms such as chest pain, breathlessness or palpitations, because these need medical assessment rather than a change in diet.
Frequently asked questions
How many times a week should I eat oily fish?
The NHS recommends at least one portion of oily fish a week as part of two portions of fish in total. Women who are pregnant, planning a pregnancy or breastfeeding should eat no more than two portions of oily fish a week.
Can I get enough omega-3 from plants?
Plant foods provide ALA, and the body converts only a small part of it into EPA and DHA. Vegetarians and vegans often choose algae-based supplements, which provide DHA and sometimes EPA directly.
Does tinned tuna count as oily fish?
In UK advice, tinned tuna does not count as oily fish, because canning removes much of the oil. Fresh tuna is classed as oily fish.
When is the best time to take omega-3 capsules?
Many people take them with a meal that contains some fat, which some find helps to reduce fishy aftertaste. Follow the dose and instructions on the pack.
Can I take too much omega-3?
EFSA has concluded that supplemental intakes of up to 5 g of EPA and DHA a day are safe for adults. Most supplements provide far less than that, but you should still stay within the dose on the label.
Sources
- EFSA: EFSA assesses safety of long-chain omega-3 fatty acids (2012)
- European Commission: EU Register of nutrition and health claims
- EFSA: Health claims
Food supplements are not medicines and should not replace a varied, balanced diet and a healthy lifestyle. This article is general information and not medical advice.