Seven things you should know about omega oils

Taken from the site :
http://www.theguardian.com/lifeandstyle/2006/feb/11/healthandwellbeing.health

Seven things you should know about omega oils
Peta Bee

• The Guardian, Saturday 11 February 2006

We've all heard that they're incredibly good for you, but have you ever wondered why? Peta Bee finds out

Why we need them

Two types of polyunsaturated fats are broken down by scientists into omega 3- and omega 6-essential fatty acids (EFAs). It is crucial to include these acids, found in every cell in the body, in our diet because the body itself cannot produce them. "Omega-3s and omega-6s have very important roles in maintaining cells," says Louise Sutton, a dietician at Leeds Metropolitan University. "Some are needed for the synthesis of prostaglandins, which help regulate blood clotting, body temperature, blood pressure, reproduction and immune function."

Where to find them

While most people in the UK eat too much omega-6, they are deficient in omega-3. Good sources of omega-3s are rapeseed, evening primrose and walnut oils, although the richest supply are fish oils. Also good are fresh seeds, especially hemp, pumpkin and sunflower, wholemeal bread, and wholegrain breakfast cereals (Shredded Wheat, Weetabix and oat flakes). Use a cold-pressed seed oil in salad dressings. Nutritionists recommend we consume two portions a week of fish, including one of oily fish such as mackerel, herring and tuna. In fact, most Britons eat only one third of a portion of fish a week - one reason our omega-3 intake is so low. Organic milk and cheese provide good additional supplies. You find omega-6s in most edible oils (notably sunflower and corn) and in meat.

How much do we need?

It is the ratio of EFAs we consume that is most important for health - the average UK diet has an omega-3 to omega-6 ratio of 1:10, whereas the recommended ratio is 1:3. Ideally, you should get as much omega-3 as you can from food sources, but if your intake is lacking, functional foods with added omega-3 are an alternative. The key omega-3s are DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid); if you take a supplement, says Sutton, make sure it has at least five parts EPA to DHA. The following are readily available in health-food shops, chemists and supermarkets: Eye Q (EFAs and evening primrose oil); Wassen osteomarine (omega-3 fish oils plus calcium and vitamins); Boots Flax Seed capsules. Efamol pure evening primrose and Seven Seas cod liver oil plus evening primrose oil are suitable for vegetarians.

Can you get too much?

Both omega-3s and omega-6s act as building blocks for the brain's neurons. But getting too much omega-6s (as most of us do) can be detrimental: a high intake prevents the body from metabolising omega-3 effectively, so cells can't carry electrical signals as best they can. "Individuals who are omega-3-rich end up with neurones that run very fast, like Pentium-III microprocessors," says Professor Tom Sanders of King's College London's nutrition department. "Those with too much omega-6 are slow and sluggish, like a 20-year-old silicon chip." Last year, a US study linked a high intake of omega-6 lipids to the growth of prostate cancer cells in men. In a recent UK survey of 14,500 families, pregnant women with diets low in omega-3s and high in omega-6s were found to have an increased risk of depression.

How they help the heart

Omega-3 deficiency, coupled with high intakes of saturated fats, has been strongly linked with a higher risk of heart disease and stroke; omega-6 oils also play a role in heart protection. Together, they help to prevent blood clotting, and to regulate or lower blood pressure. According to the British Heart Foundation, many doctors now prescribe fish oil supplements to reduce blood fats, although the BHF also recommends eating more oily fish.

They may improve mental ability

UK studies have shown that children with low omega-3 and high omega-6 intakes were more likely to suffer problems with coordination and behaviour, and to come in the bottom quarter of their class in verbal IQ tests. Some researchers have also found that low omega-3 diets during pregnancy can result in children with more behaviour problems; last year it was shown that hyperactive and dyslexic children who took supplements of fish oils or evening primrose oils saw symptoms diminish. Researchers at the University of Tel Aviv found evidence that a dietary deficiency of omega-3 and too much omega-6 is linked to depression.

What else they are good for

Undoubtedly, omega-3s are helpful to joints. Professor Bruce Caterson of Cardiff University showed that the essential fatty acids in fish oils "switch off enzymes that cause inflammation and pain of arthritis". A high intake of omega-3s can also help to stem bone loss in menopausal women and has also been linked to improving autism.