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Fish, EFAs and Omega 3

The talk of the town these days is fish oils, but what are they? We seek to answer some of the questions over these popular oils and their relatives.

What are essential fatty acids?

Essential fatty acids (EFAs) cannot be produced by the body and therefore must be supplied from the diet. There are two EFAs:

  • Linoleic acid (omega-6 fatty acid)
  • Linolenic acid (omega-3 fatty acid)

Foods containing EFAs can have varying amounts (ratios) of the two fatty acid types.

Table EFA

Omega and fats

Fish oils belong to the omega-3 fatty acid family. Many of us may be lacking in fish oils – eicosapentanoic acid (EPA) and docohexanoic acid (DHA).

So what’s the go?

All of this said and done, why are EFAs and fish oils the buzz? EFAs are used by the body in a myriad of processes and are essential for brain development especially early on, vision functioning and immunity.

Essential fatty acids (EFAs) have been extensively researched. There is an abundance of studies supporting the health giving effects of EFAs and their
therapeutic benefit in the treatment of diseases such as diabetes, eczema, arthritis and more.

Other functions include:

  • Producing energy.
  • Help to keep cell membranes fluid (although an excessive amount of EFAs may make cells too fluid or ‘sloppy’).
  • Assist in recovery after exercise (assisting in the breakdown of lactic acid).
  • Important for body tissues including the brain, adrenal glands, testes and retina.
  • Importance in foetal development, particularly that of the brain tissue.

There can be no doubt that as the research into these vital types of dietary fats continues, their health benefits and therapeutic uses will become common knowledge in the broader community.

Sources of Omega

Linoleic acid is the most important member of the omega-6 fatty acid family, as linoleic acid from the diet can be used to produce other omega-6 fatty acids. Vegetable oils and meats normally supply enough omega-6 fatty acids to meet physiological requirements. Diets that are rich in omega-6 fatty acids have been shown to lower blood cholesterol and reduce the risk of development of coronary heart disease. LA also seems to assist normalizing bad cholesterol (low-density lipoproteins (LDLs).

Linolenic acid is the primary member of the omega-3 fatty acid family. Linolenic acid from the diet can be used by the body to make omega-3 fatty acids, including EPA and DHA.

Both of these omega-3 fatty acids play an important role in:

  • The prevention of heart disease, arthritis, hypertension and cancer.
  • ormal growth and development.

EPA and DHA are:

  • Vital for optimal brain function and development as they make up much of the communicating membranes of the brain.
  • Important in visual development.
  • Essential to our anti-inflammatory responses.

It also appears that these fatty acids may be associated with attention-deficit hyperactivity disorder (ADHD) in children and teenagers.

Sources of EFAs

EFAs are found in vegetable seed oils, nuts, seeds, oily fish and the ‘germ’ of grains and cereals such as wheat. As we have seen, ground nuts and seeds can be a safe way of introducing EFAs into a young child’s diet (assuming no risk to allergy).

Evening primrose oil (EPO) shot to fame due to its reported ability to reduce the symptoms of PMT and some inflammatory diseases. While research supports this, it should be noted that EPO must be converted by our body in order to be used as anti-inflammatory substance. In order to do this the body requires certain nutrients including B6 and zinc. If these nutrients are deficient EPO can in fact be inflammatory, hence its fall from favour. Many EPO supplements come as combinations which include these nutrients. Studies have been shown them to be useful in many inflammatory conditions including eczema, dermatitis and other hormonally linked conditions.

Cod liver oil has been around for many years and you may have heard your parents or grandparents talk about having to swallow tablespoons of ghastly tasting cod liver oil for all manner of ailments. Cod liver oil is very high in vitamin A, but contains less EFAs than salmon oil (see nutrient comparisons below).

Which fish have the most EFA and DHA?

Choice (2005) reviewed a number of fish for their fish oil levels and found that white fish (which is the most common type you find commercially) have very little fish oils.

Fish that provide a minimum of 500mg of EPA and DHA per 150g serve include:

  • Atlantic salmon
  • Bonito (also recently shown to be useful in high blood pressure)
  • Gemfish
  • Mackerel
  • Mullet
  • Oreo dory
  • Sardines
  • Swordfish
  • Trevally

Even tinned fish such as mackerel, pink and red salmon and sardines (although not tuna) can be good options, all providing reasonable amounts of omega-3s.

Balancing act

The complex nature of EFAs makes the precise ratio of omega-6 to omega-3 fatty acids difficult. Currently most research points to a 6:1 ratio, with recommendations of 6% of calories from LNA and 0.25% of total calories from EPA and DHA for adults and children.

How much do we need?

Roughly we need 5-12mg of omega-6 EFAs a day and 50-200mg of omega-3 EFAs a day

Nutrient Comparison of fish oils

Cod Liver Oil
Serving size: 100.0 milliliter(s) (92.14 g)


Fats and fatty acids:
Polyunsaturated Fat 20.77 g
MFA 18:1, Oleic 19.03 g
PFA 20:5, EPA 6.36 g
PFA 22:6, DHA 10.11 g

Salmon Oil
Serving size: 100.0 milliliter(s) (92.14 g)


Fats and fatty acids:
Polyunsaturated Fat 37.16 g
MFA 18:1, Oleic 15.64 g
PFA 18:2, Linoleic 1.42 g
PFA 20:5, EPA 12.00 g
PFA 22:6, DHA 16.80

Point of interest:
*Seed meals that consist of equal parts of thoroughly ground linseed (flax seeds), sunflower seeds and almonds are a good way of providing infants (8 months and over) with essential fatty acids (for brain development), calcium, zinc and iron. Ensure that all seeds and nuts are ground up very fine to avoid any risk of choking. In children with a family history of allergy or sensitivity to nuts these may be introduced later (after 12 months or later for those with a history of allergy to nuts – 3 years).

It is also worth noting that the conversion of alpha-linolenic oil for example in flaxseed to DHA and EPA acid is very poor (around 8%) (Mori, 2005).



This article was written by Leanne Cooper, nutritionist and director of Cadence Health and Nutrition Courses and Sneakys Baby and Child Nutrition