Omega 6 & 3 - Essential fatty acids
The two main EFAs Important for human health are omega-3 and omega-6. Both need to be present in the diet and the body is unable to convert one type into the other. Whilst the amount of omega-6 eaten in Europe has risen, the amount of omega-3 consumed has fallen, Ideally the maximum ratio of omega-6 to omega-3 consumed Is 5: 1. In the UK. the ratio is nearer to 8:1 and in the US and Australia the ratio is nearer 12:1 and this imbalance has been identified as a possible cause of modem health problems.4 It is generally accepted that richer nations tend to consume enough omega-6 fatty acids, but are deficient in omega-3 so should address this imbalance by eating more omega-3 fatty acids.
The omega-3 family of polyunsaturated fatty acids can be further divided into two groups: short chains (alpha linolenic acid or ALA) and long chains (eicosapentaenoic acid – EPA and docosahexaenoic acid. D)-iA. The short chains are mainly found in plants (including some of the vegetable oils listed in the table Fatty acids and vitamin E) whereas the long chains are found almost uniquely In sea food. The human body can only utilise the long chains though short chains can be converted into long chains. There are concerns that this conversion process may be inefficient and so non-fish eaters may need to increase their consumption of EFAs. omega-3 has been shown to play an essential role In the human unborn and newborn brain and retinal development, and provide protection against heart disease, stroke and certain cancers. It has also been claimed that omega-3 can help in preventing arthritis, asthma. autoimmune diseases, Crohn’s disease. inflammatory skin diseases, depression and schizophrenia. The recommendation is to eat about 100g (3oz) oily fish per person per week. Oily fish include tuna. salmon, sardines, herring, mackerel and pilchard. The vegetable oils which have a high omega-3 level (see the table Fatty acids and vitamin E) include flax or linseed oil (53%) and walnut oil (14%). Of the more common oils. both soybean oil (7%) and rapeseed oil (9%) contain significant amounts of omega-3. Olive oil (1 %) in contrast has very low levels of omega-3 despite the numerous health claims made about the oil.