Omega-3 and fish oil supplements

Easy-to-read medicine information about omega-3 and fish oil supplements.

Key points

  1. Omega-3 fatty acids are found in foods, such as oily fish, flaxseed, walnuts and pumpkin seeds and in dietary supplements, such as fish oil.
  2. The main omega-3 fatty acids are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and alpha-linolenic acid (ALA). You need to get most of your EPA and DHA from food as your body can only make very small amounts from ALA.
  3. Omega-3 fats are found in many cells in your body, but especially in cells in your brain and eyes. They play an important role in helping your blood vessels, heart, immune system and lungs work properly. 
  4. In New Zealand it’s recommended that adults have 2 servings of oily fish a week to provide omega-3 fatty acids, which may help to reduce the risk of heart disease.  
  5. If buying fish oil supplements, look at the amount of EPA and DHA contained in the capsule, tablet or liquid. 

What are omega-3 fatty acids?

Omega-3 fatty acids are a type of polyunsaturated fats. Polyunsaturated fats are often referred to as ‘good fats' as they are important in your diet and don’t increase LDL cholesterol levels, unlike saturated and trans fats. Read more about cholesterol and fats and oils

The main omega-3 fatty acids are docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and alpha-linolenic acid (ALA). These are found naturally in some foods.

Fish sources of omega-3 are also called long-chain (LC) omega-3 fatty acids. These work differently in your body to ALA. You need to get most of your EPA and DHA from food as your body can only make very small amounts from ALA.

Sources of DHA and EPA Sources of ALA
These are found in oily fish, such as sardines, salmon, trout and mackerel. ALA is found in plant foods such as flaxseeds, soybean, chia seeds, walnuts, pumpkin seeds and canola oil.

The amount of omega-3 in fish varies between species of fish and whether they are farmed or fresh fish. Oily fish like fresh tuna, fresh or tinned salmon, sardines, pilchards and mackerel are higher in omega-3. White fish and sea food (oysters, eel and prawns) have a lower omega-3 content.

Why are omega-3 fatty acids important?

Omega-3 fats are found in many cells in your body, but especially in cells in your brain and eyes. They play an important role in helping your blood vessels, heart, immune system and lungs work properly. This is why including foods that are high in the omega-3 fats, EPA and DHA, from oily fish is encouraged as part of a healthy balanced diet. 

Regularly eating foods high in omega-3 fatty acids (oily fish) or taking an omega-3 supplement is also thought to help reduce the risk of developing age-related macular degeneration, Alzheimer’s disease and dementia, and may reduce inflammation seen in rheumatoid arthritis.1

You may have heard about taking fish oil supplements to help reduce the risk of heart disease. However, results of a recent meta-analysis (review of all the research) indicates that taking regular omega-3 capsules has little or no effect on your heart health.2 

How often should I eat oily fish?

In New Zealand it’s recommended that men have 610mg of long chain omega-3 daily, and women have 430mg daily to reduce the risk of heart disease. This is 2 servings of oily fish a week.3 A serving of fish is:

  • 125–150g raw fish – about the size of your hand (palm and fingers)
  • a 95g tin of tuna – about 100mg of omega-3
  • a 105g tin of pink salmon – about 120mg of omega-3.

Tinned salmon, mackerel, sardines and pilchards can be a great way to get more omega-3. Fish tinned in brine is high in sodium which can increase blood pressure and increase your risk of heart disease. Choose fish tinned in spring water, or rinse the fish thoroughly to remove the brine and sodium. Remember that flavoured tinned fish may also contain added sugar and sodium.

Omega-3 and fish oil supplements 

There are a variety of omega-3 and fish oil supplements that can be bought from pharmacies, supermarkets, health shops and online. They are available as capsules, tablets and liquid. There are currently no New Zealand recommendations for taking omega-3 and fish oil supplements. It is best to get omega-3 from food.

Not all fish oil supplements are created equally. Unlike medications, fish oil supplements do not need to be approved by the medicines regulatory organisation in New Zealand, Medsafe. This means that manufacturers can sell supplements simply with "claims" of safety and effectiveness.

Tips about using omega-3 and fish oil supplements

When choosing fish oil supplements
Look at the amount of EPA and DHA contained in the capsule, tablet or liquid, rather than the fish oil content. For example, the product label on a fish oil supplement may say the following: 
Each capsule contains: Fish oil – Natural 1.5g equiv. Eicosapentaenoic acid (EPA) 270mg, Docosahexaenoic acid (DHA) 180mg.

In this example, each capsule has EPA + DHA = 270mg + 180mg = 450mg of omega-3. If you are unsure about how to read the labels of fish oil supplements, ask your pharmacist for advice.

Interactions with medicines 
Omega-3 can have blood thinning effects when taken in high doses. Seek medical advice before taking doses of omega-3 supplements, especially if you are taking anticoagulant medication such as warfarin.

Seafood allergy
Although the risk of allergic reactions to fish oil supplements is considered to be low in people allergic to fish, due to the method of purification, it is recommended that you seek medical advice before taking fish oil supplements. Read more

Learn more

The following links have more information about omega-3. Be aware that websites from other countries may have information that differs from New Zealand recommendations.

Omega-3 fatty acids National Institutes of Health, US
Omega-3 The Association of UK Dietitians, UK 
Sources of  omega-3 Heart Foundation, Australia
Omega-3 and mood disorders Black Dog Institute, Australia
Allergic and toxic reactions to seafood Australasian Society of Clinical Immunology and Allergy

References

  1. Omega-3 fatty acids National Institutes of Health
  2. Omega‐3 fatty acids for the primary and secondary prevention of cardiovascular disease Cochrane Library, 2018
  3. Guide to eating for a healthy heart Heart Foundation, NZ
  4. Kai moana – food from the sea Heart Foundation, NZ

Reviewed by

Katrina is a New Zealand Registered Dietitian. As a freelance nutrition, health and wellness writer she specialises in making complex health concepts easy to understand.
Credits: Sandra Ponen, Pharmacist. Reviewed By: Katrina Pace, New Zealand Registered Dietitian Last reviewed: 21 Oct 2019