Omega-3s and heart health

Omega-3s and Heart Health

This fact sheet explains why eating food that contains omega-3 fat is good for your heart health, and provides information on how much you need and food sources of these healthy fats.

What are omega-3 fats?

Omega-3 polyunsaturated fatty acids are essential fatty acids, meaning that your body can’t make them; you must get them through your diet. Omega-3s help to reduce inflammation in the body and protect against heart disease. There are several types of omega-3s that can be found in food:

• Eicosapentaenoic acid (EPA) & docosahexaenoic acid (DHA) are important for your heart, blood vessels, lungs, immune and hormone systems. These are mainly found in oily fish.
• DHA is also important for the development of the retina (eyes) and brain in infants.
• Alpha-linolenic acid (ALA) is
  a type of omega-3 found in plant-based foods. The body can make EPA and DHA from ALA.

Where can omega-3s be found?

*Canned tuna does not count as a portion of oily fish. The omega-3 fatty acids in tuna are lost during the canning process.

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

Benefits of eating oily fish

Fish forms a valuable part of a healthy, balanced diet and oily fish are an excellent source of omega-3, vitamins A and D, protein and minerals such as iodine, calcium and selenium. As few other foods contain EPA & DHA omega-3 fats, fish is one of the best sources. Omega-3 fat found in oily fish may protect the heart and blood vessels from disease, help support healthy

heart rhythm and prevent clots. They also
helps to lower a type of fat in your blood called triglycerides. Too much triglycerides in your blood raises the risk of atherosclerosis (the build-up of plaque in your arteries), and through this, can increase your risk of heart disease and stroke.

Omega-3 enriched foods

If your diet is plant based or you do not eat fish, foods that have omega-3 added can be a useful source. These foods will be labeled ‘a source of omega-3 fatty acids’ or ‘high in omega-3 fatty acids. Typical foods enriched with omega-3 include eggs, milk, spread and orange juice. 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.

How much should we eat?

The general population (adults and children older than 5 years of age) should try to eat two portions of fish per week, one of which should be oily. As a guide, a portion for adults is the same size as the width and depth of an adults palm (without fingers and thumb) which is equal to 140g of fresh fish, or 1 small can of tinned fish.

Some ways to include oily fish in the diet include:

• Tinned sardines on toast with sliced tomato
• Tinned salmon on a salad, baked salmon fillet with a jacket potato and peas
• Grilled mackerel with pasta and tomato and vegetable sauce

Ways to add vegetarian sources of omega-3 to your diet include

• Add walnuts to your morning porridge
• A mix of sunflower, pumpkin, chia and flaxseed with yogurt and fruit
• Use rapeseed oil or a sunflower oil or an omega-3 enriched spread

Is eating fish safe?

There are some safety concerns about eating oily fish due to its content of chemicals e.g. mercury, dioxins and PCB’s. Mercury can cross the placental barrier and have harmful effects on foetal brain and nervous system development. The Food Safety Authority of Ireland (FSAI) advises that a healthy diet should include two portions of fish per week, including one portion of oily fish with the following guidance for specific groups:

• Women of childbearing age (in particular, those intending to become pregnant), pregnant and breastfeeding women should avoid eating shark, swordfish and marlin due to their high content of mercury and should limit their consumption of tuna to not more than 1 fresh tuna steak (approximately 225 g/8 oz) or 2 medium cans (225 g/8 oz) of canned tuna per week.
  
  
• The diet of young children (under 10 years of age) should not include shark, swordfish or marlin and intake of tuna should be limited as above.
  
  
• Consumers other than the above groups should restrict their consumption of shark, swordfish or marlin to not more than one portion per week, but do not need to limit their consumption of tuna.

What about supplements?

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, whereas supplements only contain specific nutrients.

If you choose to take an omega-3 supplement you should:

• Be wary of the vitamin A content - too much vitamin A can be harmful. Your daily intake of vitamin A from food and supplements combined should not exceed 1500μg.
• Choose omega-3 rather than fish liver oil, as fish liver oil contains less omega-3s and is naturally higher in vitamin A.
• If you are pregnant or breastfeeding, avoid supplements that contain vitamin A, as large amounts of vitamin A in pregnancy can cause birth defects.
• Choose a supplement that will provide 450mg 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 your doctor has prescribed omega-3 supplements to treat hypertriglyceridaemia, continue to take these.

Omega-3 and Heart Health 823.08 KB

Created by the Cardiology Interest Group of the Irish Nutrition & Dietetic Institute. September 2025

© 2025 Irish Nutrition and Dietetics Institute, INDI. All rights reserved. May be reproduced in its entirety provided the source is acknowledged. This information is not meant to replace advice from your medical doctor or individual counselling with a dietitian. It is intended for educational and informational purposes only.