Fish, Fats and the Facts

1 April 2005

Publication: Special!

Research into fatty acids and their importance for children has produced a lot of controversy over the years. Jackie Stordy presents the facts.

It is nearly ten years since the first fatty acid supplement for people with conditions such as dyslexia, ADHD and dyspraxia became available, initially in the UK and then very soon afterwards in many other countries around the world. But there is still confusion about which fats are important and why, so here are the answers to some frequently asked questions.

What are essential fatty acids?

Strictly speaking there are two, and only two essential fatty acids: linoleic acid (LA) and alpha-linolenic acid (ALA). These fatty acids must be part of our diet because the body cannot make them and they are vitally involved in the proper functioning of every tissue in the body.

ALA is an Omega-3 fatty acid and LA an Omega-6 fatty acid. Omega-3 fats cannot be converted to Omega-6 or vice versa. That is why we need both.

Both ALA and LA have 18 carbon atoms in the chain-like molecule. To fulfil some of their vital functions they are converted to longer-chain fatty acids with 20 or 22 carbon atoms in the chain. The carbon chains also have another important chemical feature, so called double or unsaturated bonds between some of the carbon atoms. LA has two of these onds and ALA three. The position of the first double bond is important and is called either Omega-3, when the first double bond is on the third carbon atom, or Omega-6, when it is on the sixth carbon atom.

Vegetable oils provide LA and ALA but each vegetable oil has different amounts of the two fatty acids. We need more LA than ALA, but no more than ten times as much. However, many oils have much more; rapeseed oil, blended vegetable oil, walnut oil and soya bean oil have a good ratio of the two fats but sunflower, sesame, corn and peanut oil have excessive amounts of LA.

What are the long chain polyunsaturated fats?

The essential fatty acids are transformed in the body by adding carbon atoms to the chain and by adding more double bonds. LA is converted to arachidonic acis (AA) with 20 carbon atoms and four double bonds and the adrenic acid (ADrA) with 22 carbon atoms also with four double bonds. ALA is converted into eicosapentaenoic acid (EPA) with 20 carbon atoms and four double bonds and then docosahexaenoic acid (DHA) with 22 carbon atoms and six double bonds. These fatty acids with more than 20 carbon atoms are called long chain polyunsaturated, LCPs for short.

The importance of fatty acids

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