Miriam Polunin takes a look at current thinking on Omega 3s and how they relate to food allergy and food intolerance.

Confused about oils and fats - not to mention Omega-3s and 6s? Well, join the club. It is a struggle for even nutritionists to keep up these days.

Current thinking is that, in the general population, there should be a balance between the intake of omega-3 and omega-6 fatty acids. But this balance has been dramatically tipped in favour of omega-6s over the last 20 years by the huge increase in the use of high omega-6 vegetable oils such as sunflower and soya. There is a growing body of opinion which claims that the increase in omega-6 consumption has been to the detriment of our intake of omega-3s. What is more, it may be the scarcity of the latter in the average diet which is responsible for the dramatic increase in depression, hyperactivity, autism and other neuro-psychiatric disorders.

However, it is not that simple because omega-3 fatty acids are very vulnerable to oxidation and rancidity. Even when generous amounts of anti-oxidant Vitamin E are added by responsible manufacturers, dealing with these beneficial fats (converting them into the highly unsaturated fatty acids EPA & DHA that our systems actually need) takes up considerable amounts of the body’s anti-oxidant resources.

None the less, most people would benefit by increasing the proportion of omega-3 fatty acids in their diet.

Apart from any neuro- psychiatric effects they may have, Omega-3s reduce the likelihood of a blood clot and of heart arrhythmias. One study found that 1 gram of EPA and DHA daily reduced coronary heart disease by 20%. Omega-3s have also been shown to help relieve inflammation in psoriasis, Crohn’s Disease, asthma and, in larger doses, in rheumatoid arthritis - and to reduce the risk of mature onset diabetes.

Adequate DHA during pregnancy and breastfeeding is now accepted as necessary for good eyesight and intelligence development in babies, while it is also thought that insufficient EPA & DHA may be a factor in dyslexia and mood swings.

Food versus supplement
For those who would rather eat their Omega 3s as a food than a pill, one large portion of oily fish (sardines, salmon, herrings, pilchards, anchovies) would be sufficient for the average person’s needs. But in reality only one third of the UK population eat oily fish regularly and in amounts far too small to achieve this target. This is compounded by the current concern about fish and fish oil containing levels of sea-polluting heavy metals and toxic chemicals.

Plants versus fish
So what other oils can contribute most to providing more omega-3? One, if not the tastiest, is rapeseed (canola) oil. Its increased availability in the UK is leading to more use in place of sunflower and corn oil (both very high in Omega-6) and therefore an inadvertent increase in omega-3 consumption.

Of the single organic oils the richest, by far, in omega-3 is linseed/ flax. As a result a number of manufacturers are selling pure flax oil. Unfortunately it tastes very bitter, even when diluted (as in Clearspring’s Omega Oil) with rape, sunflower and olive oils.
Hemp seed oil is much more palatable and contains an almost ideal ration of Omega 3s & 6s. Soya and walnut oil also contain substantial amounts of omega-3 but soya is one of the highest in omega-6s.

But do the plant oils have as many benefits as the EPA & DHA rich fish oils?

In theory, the omega-3 fatty acids they contain, in the form of alpha-linolenic acid (ALA) can be broken down by the body into EPA and DHA. But in fact this rarely seems to happen with only about one seventh of the ALA consumed by subjects in a 2002 trial being converted to EPA, and virtually none to DHA.

Essential Fatty Acid supplement makers such as Barleans now add extra ingredients such as phyto-estrogens and lignans to help the conversion of ALA but it is not certain how successful this is.
But although relatively little plant derived omega-3 may be converted into EPA/DHA, an increased intake at least has the benefit of reducing our intake of Omega-6s and somewhat redressing the balance.

Caring for your omega-3s. Beware.
Omega-3 oils break down very quickly if heated so, if they are to be used as a food, they can only be used cold - either as a salad dressing or drizzling oil, or as a flavour enhancer - a spoonful ‘drizzled’ over a hot dish just before serving.

You also need to take care how you store your oils. Because of their instability contact with both air and light will cause them to go rancid very quickly. Only buy and store oils in dark bottles, tightly closed and, ideally, chilled. Aim to finish them within a couple of weeks of opening.

It goes without saying that you must also be careful which oils you buy. If they are to deliver their full nutritional value (and flavour) they need to be made from whole fresh seeds and nuts which have been cold pressed and both stored and transported in darkened and chilled containers. You will find most of the therapeutic oils in the fridges of health food stores. Do not buy an oil that has a ‘shelf life’ (a ‘best before’ date) of more than 6 months.

What you should be eating
Estimated fat needs for an average healthy adult eating 2,000 calories a day
• EPA & DHA - 1.5grams per week (1 large helping of oily fish)
• Omega-3 - 2-3 grams per week (1/2 teaspoon linseed oil or 1 teaspoon hemp)
• Omega-6 - maximum 10% of energy / 22 grams (1 tablespoon soya oil plus some from seeds, nuts or other foods)
• Linoleic acid - minimum 0.3grams per day (1 teaspoon soya oil)
• Saturated fats - no more than 10% of energy
• Transfats - maxim,um 2% of energy/ 4-5 grams (in bought biscuits, pastry etc ) although many people would rather avoid them altogether.
• Mono-unsaturated fats - no requirement set.

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First Published in 2004

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