Oily fish & omega-3

Oily fish and some plant foods are excellent sources of essential omega-3 fats, which are particularly beneficial for heart health. Eating more omega-3-rich foods may help protect against heart attacks and strokes.

What are omega-3 fats?

Omega-3 fats are a type of unsaturated fat – the kind that's good for your cholesterol levels. For a heart-healthy diet, it’s important to swap out saturated fats for unsaturated fats.

Omega-3 fats are essential, which means your body can't make them, or can't make enough of them. This is why we need to get them from the foods we eat.

The three main types of omega-3 fats

Plant omega-3: ALA (alpha-linolenic acid)

ALA is found in a few plant foods, like walnuts and seeds, and oils made from them. Since our bodies can’t make ALA, it’s important to include these foods in your diet.

EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)

These omega-3 fats are mainly found in oily fish, but can also be found in algae and seaweed. Our bodies can only make small amounts of EPA and DHA, so we need to get them from food. White fish and shellfish contain only tiny amounts of omega-3.

Why are omega-3 fats good for heart health?

There’s lots of research showing that foods rich in omega-3 (ALA, EPA and DHA) can improve heart health and blood vessels carrying blood to the heart.

EPA and DHA omega-3 fats have been shown to also:

• Prevent blood clots
• Lower blood pressure
• Keep the rhythm of your heart steady.

Omega-3 from food is better than supplements

While research is still ongoing, experts believe that omega-3 from food are more beneficial than supplements as omega-3-rich foods provide other heart-healthy nutrients, too.

• Oily fish and plant foods rich in ALA are low in saturated fats and contain other unsaturated fats. This helps create an ideal fat balance for lowering cholesterol.
• Omega-3-rich foods often replace foods high in saturated fats. For example, oily fish can replace red meat, and nut and seed oils can replace butter or animal fats. This helps improve your overall fat balance and lower cholesterol.
• Cholesterol-busting foods. Walnuts, rich in ALA omega-3, are one of the super cholesterol-lowering foods.
• Nuts and seeds also contain fibre, antioxidant vitamins, and plant compounds called phytonutrients, all of which are linked to better heart health.

When omega-3 supplements may be prescribed For some people with very high blood triglyceride levels, doctors may prescribe high-dose omega-3 supplements as part of their treatment. These cannot be bought over the counter.

Which foods contain omega-3?

Jump to:  Oily fish ♦ White fish ♦ Plant foods ♦ Fortified foods ♦ Supplements

Oily fish

How much should you eat?

Aim to eat at least one portion of oily fish every week.

• Oily fish is the richest source of omega-3 fats EPA and DHA., and just one serving a week will meet your requirements.
• This is in addition to one serviing of white fish every week.

What's a portion?

• A standard portion is 140g of fresh or frozen fish.
• For tinned fish, a portion is 90g or a small can. Choose options in tomato sauce or olive oil rather than brine or sunflower oil.

If you prefer smaller portions, you can spread this across the week.

Which oily fish are good sources of omega-3?

Fresh, canned, or frozen oily fish are all excellent choices.

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

What doesn't count: fresh and canned tuna are not good sources of omega-3.

Additional benefits of oily fish

Oily fish are also rich in essential vitamins and minerals, many of which are under-consumed in the UK. These include:

• Vitamins: A, D, and B vitamins.
• Minerals: Iodine, zinc, iron, and selenium.
• Calcium: found in oily fish with soft edible bones, such as pilchards and anchovies.

Can you eat too much oily fish? Oily fish can contain higher levels of pollutants, so certain groups need to limit their intake. All oily fish Girls, women who are pregnant, breastfeeding, or planning a pregnancy should eat no more than two portions of oily fish per week to minimise pollutant build-up. Shark, marlin, and swordfish: These species contain higher levels of mercury. Pregnant women, those planning a pregnancy, and all children should avoid them entirely. Other adults should limit consumption to one portion per week. For more information on white fish and pollutants, visit NHS Live Well.

White fish and shellfish

Nutritional benefits

While white fish and shellfish are not rich in omega-3 fats, they are highly nutritious. 

They provide:

• An excellent lean source of protein.
• Very low levels of saturated fat and calories.
• The richest dietary sources of iodine, essential for growth, hormone regulation, and cognitive function – many people in the UK need more iodine.
• Vitamin B12 and minerals such as selenium, magnesium, and potassium.

 

What about cholesterol in shellfish? Although shellfish contains some cholesterol, it generally does not affect blood cholesterol levels. It’s fine to enjoy shellfish as part of a healthy diet.

How much should you eat?

Aim to eat at least one portion of white fish or shellfish every week in addition to your weekly serving of oily fish.

You can also spread this over the week with smaller portions.

• What counts as a portion? A portion of is 140g, similar to oily fish.
• Which white or shell fish count? You can choose any white fish that is fresh, canned or frozen.

Support Sustainable Fishing Overfishing and harmful practices have damaged marine ecosystems and fish populations. By supporting sustainable fishing, you can help protect our oceans for future generations. How to identify sustainable fish: Ask your fishmonger: They can recommend the most sustainable options. Use the Good Fish Guide: Visit the Marine Conservation Society’s Good Fish Guide for country-specific recommendations. Look for logos: When buying pre-packed fish, look for the Marine Stewardship Council (MSC) or Aquaculture Stewardship Council (ASC) logos, which indicate strict sustainability standards.

  Plant foods with omega-3

A few plant foods are rich in the omega-3 fat, ALA, which research has shown to help protect the heart.

As the body cannot make ALA at all, it's important to include foods rich in ALA and especially if you do not normally eat oily fish.

Good plant-based sources of ALA 

• Nuts: Walnuts are the only nut rich in ALA. Half a handful daily meets your needs.

 

• Seeds: Flax (linseed), chia, and hemp seeds. One tablespoon daily provides enough ALA.

• Oils:

  • Rapeseed oil (standard UK vegetable oil): 1 tablespoon daily.

  • Soya oil: 1 tablespoon daily.

  • Walnut oil: 2-3 teaspoons daily.

  • Flaxseed (linseed) oil: 1 teaspoon daily.

  • Hemp oil: 1-2 teaspoons daily.

• Other plant foods such as green leafy vegetables, eggs, and other nuts and seeds contain smaller amounts of ALA but still contribute to your intake.

Tips for meeting your ALA needs

• Use rapeseed oil for cooking – it’s versatile and affordable. Soya oil is also good for cooking.

• Use seed and nut oils as salad dressings or drizzled over meals – avoid using them in cooking.

• Stir a teaspoon or two of chia seeds into your oats when making porridge, and top with fresh berries for a tasty, omega-3-rich breakfast.

• Sprinkle flax, chia, or hemp seeds over cereals, stir fries, stews, soups, curries or salads.

• Snack on walnuts or add them to breakfast cereals, salads, or low-fat yogurt.

Foods fortified with Omega-3

Some foods are fortified with omega-3 fats, such as eggs and some frozen fish.

Check the label to identify the type and amount of omega-3.  Most fortified foods contain ALA rather than EPA or DHA. Remember, EPA and DHA are the most beneficial for heart health.

Omega-3 supplements

Here at HEART UK, we recommend getting your omega-3 from food rather than supplements. Foods provide a wide range of nutrients that work together to support your health, while supplements only provide specific nutrients.

If you choose to take an omega-3 supplement, follow these guidelines:

• Avoid fish liver oils as they contain less omega-3 and too much vitamin A.
• Choose a supplement with less than 1mg of vitamin A (also written as 1000µg or 1000mcg).
• Pregnant or breastfeeding women should avoid supplements containing vitamin A.
• Aim for 500mg of EPA and DHA combined daily – equivalent to a 140g portion of oily fish per week.
• Speak to your doctor before taking supplements if you’re on blood-thinning medications, such as aspirin or warfarin.
• Vegans or vegetarians can take marine oils made from algae.
• If your doctor prescribes omega-3 supplements to treat hypertriglyceridaemia, continue taking them as directed.

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