Omega 3 fats

Omega 3 fats are a group of unsaturated fats that we need to stay healthy, especially for heart health. Eating foods high in omega 3s could help to prevent heart attacks and strokes.

There are different types of omega 3s which are found in different foods. The main ones are:

  • ALA (alpha linolenic acid)
    ALA is essential for good health, but our bodies can’t make it, so we need to get it from the foods we eat. It’s mainly found in vegetable oils, nuts and seeds.
  • EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)
    We need these types of omega 3 fats for a healthy heart and blood circulation. Our bodies can make some of these fats from the ALA in food, but only a small amount. So, it’s good to eat foods that already contain them.

    Oily fish such as sardines, salmon and mackerel are the best source of EPA and DHA. White fish and shell fish contain some omega 3s, but in smaller amounts.

Why are Omega 3 fats good for health?

There has been lots of research into Omega 3 fats and oily fish and how they can improve heart health.

In countries where people eat more oily fish, such as in the Mediterranean, Greenland and Japan, fewer people have heart disease compared to countries where people eat very little oily fish, such as the UK.

The Omega 3 fats EPA and DHA can help protect the heart and blood vessels from disease: They can help:

  • lower triglycerides (a fat that enters our blood after a meal)
  • improve circulation (blood flow around the body)
  • prevent blood clots
  • lower blood pressure
  • keep the rhythm of your heart steady.

In the past, higher levels of the Omega 3 fats EPA and DHA in the blood have also been linked with a lower risk of dying from cardiovascular disease. There is still research on-going, but doctors think that the benefits come from eating foods that contain omega 3s rather than over-the-counter supplements. However, some high-dose Omega 3 supplements may be prescribed by your doctor to treat hypertriglyceridaemia.

Which foods contain omega 3s?

Oily fish

Oily fish is the best source of Omega 3 fats. Aim to eat two portions of fish per week. At least one of which should be oily. A portion is 140g, but you could have two or three smaller portions throughout the week.

All oily fish contain omega 3 fats. You can choose from fresh, canned or frozen fish. The following are all good options.

  • anchovies
  • bloater
  • carp
  • eel
  • herring (kippers)
  • mackerel
  • pilchards
  • salmon
  • sardines
  • sprats
  • swordfish
  • trout
  • whitebait.

Eating oily fish not only means you’ll be getting Omega 3 fats. They’re good for you in other ways too. They’re a source of vitamins A and D and the B vitamins, and minerals including calcium (from the small bones), iodine, zinc, iron and selenium. These are nutrients that many of us don’t eat enough of.

How much is too much?

Some fish contain small amounts of chemicals or metals that may be harmful if you eat a lot of fish. In general, it’s safe to have four portions of oily fish per week.

Shark, marlin and swordfish can contain mercury. Eat no more than one portion of these per week.

If you are pregnant, planning to get pregnant, or breast feeding, you should eat no more than two portions of oily fish per week. Avoid shark, marlin and swordfish altogether.

Plant foods which contain Omega 3s

A number of plant foods are high in the omega 3 fat, ALA. Try to eat more of these, especially if you don’t normally eat fish or if you are vegetarian.

The plant foods which are good sources of omega 3s are:

  • some oils including flax (also known as flaxseed oil and linseed oil), walnut, soya, pumpkin and algal oil
  • green leafy vegetables
  • nuts, especially walnuts
  • seeds, especially flax (linseed), pumpkin, chia and hemp seeds.

Foods which are fortified with Omega 3s

Some foods have omega 3 fats added to them. These include:

  • eggs
  • some frozen fish.

Check the label for the amount and kind of omega 3. Foods are often fortified with ALA rather than EPA or DHA. It’s EPA and DHA that’s most important for heart health.

What about supplements?

Here at HEART UK we don’t recommend supplements of Omega 3s. It’s always best to get your nutrients from foods rather than supplements. 

That’s because foods contain a whole range of different nutrients which improve your health in different ways. But supplements only contain specific nutrients.

If you choose to top up on Omega 3s by using over-the-counter supplements, follow these golden rules.

  • Choose a fish oil or an Omega 3 supplement.
  • Don’t choose fish liver oils, they contain less Omega 3 than fish oils and too much vitamin A.
  • Go for a supplement with lower levels of vitamin A – less than 1mg per day (which might be written as 1000ug or 1000mcg).
  • If you are pregnant or breastfeeding, avoid supplements that contain vitamin A (sometimes written as retinol) altogether. Beta carotene (a form of vitamin A is safe for pregnant women).
  • Aim to get 500mg of EPA and DHA combined each day, this works out as around the same as a 140g portion of oily fish per week.
  • If you take medicines to thin your blood, such as aspirin, warfarin or heparin, speak to your doctor before taking fish oil supplements – they can also thin your blood.
  • If you are vegan or vegetarian, you can take marine oils made from algae.


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