What is oily fish?

Oily fish are certain types of fish that are high in omega-3 fatty acid. Omega-3 fatty acid is considered an essential fatty acid because the body can only get it from food as it is unable to make it by itself. Omega-3 fatty acid is a polyunsaturated fat, and is made up of two main fatty acids:

  • EPA (eicosapentaenoic acid)
    DHA (docosahexaenoic acid)

Types of oily fish

The following fish are best known for being an oily fish:
• Salmon
• Mackerel
• Anchovies
• Sardines
• Herring

A really easy way to remember is the acronym 'S.M.A.S.H': salmon, mackerel, anchovies, sardines, herring. Different types of herring (kipper, bloater and hilsa) as well as sprats and trout are also included in this list.

Top 5 benefits of oily fish

1. May help protect against heart disease

Omega-3 fatty acid has been shown in numerous studies to help factors such as high cholesterol and high blood pressure, thereby reducing the risk of heart disease.

Salmon broccoli traybake

2.Has neuroprotective properties

Omega-3 fatty acid, especially DHA, is required for proper brain development and function and offers neuroprotection against conditions, including Alzheimer's.

3. May protect joints

Omega-3 fatty acid is naturally anti-inflammatory and has been shown in several studies to offer protection of joints, and may even help in the prevention of rheumatoid arthritis.

South indian fish curry with chickpeas

4. May help support good mental health

Omega-3 fatty acid has often been shown to have a positive impact on mental health, including anxiety and depression.

5. Helps reduce the risk of certain cancers

Lots of research has shown links with omega-3 fatty acid and a reduced risk of certain cancers, including colon, breast and prostate.

How much oily fish should we eat?

The NHS currently recommends that we include at least two portions of fish in our diet a week, one of which should be an oily fish. One portion is about 140g.

For most people, eating more than one portion of oily fish a week is fine, but there are certain groups for which this is not recommended, because oily fish do contain low levels of pollutants that can build up in the body.

Those who should not eat more than two portions of oily fish a week are:

  • Girls
  • Women planning a pregnancy
  • Pregnant and breastfeeding women

Should I be concerned about mercury levels in oily fish?

Larger fish tend to contain the most mercury compared to smaller breeds such as sardines and anchovies, but you shouldn’t be afraid of eating fish. Eating a few servings a week is safe and only those at a higher risk – such as pregnant and breastfeeding women – should keep to the recommended limits.

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Lower mercury fish include salmon and sardines, whereas king mackerel is one of the higher mercury fish and is best avoided.

What about sustainability of oily fish?

The main sustainability concerns are with salmon and the potential for over-fishing. You can buy farmed salmon or look for stamps such as the blue MSC label (Marine Stewardship Council) to ensure your salmon has been sustainably caught. Pacific salmon is the better choice at the moment, as Atlantic salmon numbers are low.

As for mackerel, handline-caught mackerel is the most sustainable type you can buy, as this fishing method is low impact. Or, look for farmed mackerel. North-east Atlantic mackerel numbers are currently in healthy states, too. There has been a lot of competition for mackerel fishing over the years, and in 2019, it was over-fished. As a result, all UK fisheries lost their sustainability certifications. You can find mackerel from other countries, such as Iceland and Norway.

Smaller oily fish, such as sardines and anchovies, have various sustainability issues and this can vary based on stocks. The Marine Conservation Society has a Good Fish Guide that is an easy reference to check current sustainability levels for many different fish and is updated annually.

Oily fish recipes to try

Spiced salmon & tomato traybake
Soy salmon & broccoli traybake
Grilled mackerel with soy, lime & ginger
Courgette & anchovy salad
Grilled harissa sardines with fennel & potato salad
Kipper fish cakes with watercress mayo
Tangy trout

This article was published on 6 September 2021.

Nicola Shubrook is a nutritional therapist and works with both private clients and the corporate sector. She is an accredited member of the British Association for Nutrition and Lifestyle Medicine (BANT) and the Complementary & Natural Healthcare Council (CNHC). Find out more at urbanwellness.co.uk.


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