Omega 3 fats

Omega 3 fats are a group of fats we need to stay healthy. They're especially good for heart health, and eating them could help to prevent heart attacks and strokes.

Omega 3 fats are a type of unsaturated fat – the type of fat that’s good for your cholesterol levels. The other main type of fat is saturated fats, which raise your cholesterol levels. For a heart-healthy diet, it’s good to swap saturated fats for unsaturated fats.

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

• ALA (alpha linolenic acid)

  Our bodies can’t make ALA, 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)

  Our bodies can make some EPA and DHA from ALA in the food we eat, 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 your blood after a meal)
• improve circulation (blood flow around the body)
• prevent blood clots
• lower blood pressure
• keep the rhythm of your heart steady.

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.

Oily fish are good for you in other ways too. They contain 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.

What about white fish and shell fish?

White fish and shell fish contain smaller amounts of omega 3s, around a tenth of the amount in the same weight of oily fish. But they’re also low in saturated fat and calories.

While shellfish contains some cholesterol, this doesn’t generally affect the amount of cholesterol in your blood so it’s usually fine to eat some shellfish

How much is too much?

Oily fish contain higher levels of pollutants than other types of seafood. Girls, women who are pregnant or breastfeeding, planning a pregnancy or may have a child one day should eat no more than two portions of oily fish a week because the pollutants could build up in the body and affect the pregnancy. 

Shark, marlin and swordfish can contain mercury. Children, pregnant women and women who are trying to get pregnant should not eat any of these. Other adults should eat no more than one portion per week.

Some white fish can also contain pollutants. Find out more from NHS Live Well. 

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're vegetarian or don’t normally eat fish: 

• 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.

To get more of these into your diet, try sprinkling flaxseed over your porridge, cereals, or nuts and seeds over your salads. And switch your oil to one of those listed above.

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 an over-the-counter fish oil or Omega 3 supplement, follow these golden rules.

• 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.
• 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 – as they can also thin your blood.
• If you are vegan or vegetarian, you can take marine oils made from algae.

• If your doctor has prescribed Omega 3 supplements to treat hypertriglyceridaemia,  continue to take these.

Learn about eating less salt for a healthy heart