Omega-3

Omega-3s in the public eye

A flurry of products - eggs, fruit juices, breads, margarines and spreads and kids' drinks - topped up with omega-3 has been arriving on the supermarket scene with often extravagant accompanying claims.

'The nation's children are in need of an omega-3 boost,' says one. 'Helping brains, helping hearts' claims another. 'Eating long-chain omega-3s like those found in salmon may protect you from sunburn', another even suggests. At the same time an advertisement for milk with added omega-3 has been reprimanded for giving the impression it can help increase children’s intelligence.

Omega-3 research

Generalising about the health benefits (or otherwise) of omega-3 is clearly not straightforward. A few years ago, the Government considered administering fish oil supplements, which are high in omega-3s, to schoolchildren, with the aim of improving school results. Subsequently, however, the Food Standards Agency (FSA) concluded that there was insufficient evidence that fish oil can improve children's learning skills to warrant such a step.

Similarly, years of research appeared to confirm that regularly eating oily fish or taking fish oil supplements (the best source of long-chain omega-3 fatty acids) cuts the risk of heart disease. Yet, in early 2006, a review published in the British Medical Journal by scientists at the University of East Anglia raised doubts about these claims.

After analysing existing research into omega-3, its surprise conclusion was that there was little evidence that fish oil could reduce the risk of dying from heart disease or stroke. Indeed, it even suggested that fish oil supplements could increase the risk.

However, these findings shouldn't change the prevailing attitude to omega-3, that it's a necessary part of a healthy diet. It doesn't alter the Government's advice to eat oily fish. Even the author of the University of East Anglia report, Lee Hooper of the University's School of Medicine and Health Policy, isn't calling for these recommendations to change, but suggests that there should be more research to find out whether it is right to recommend large amounts of fish oil to people with heart disease.

What is omega-3?

There are three types of fat: saturated; monounsaturated (olive oil is the best known); and, even more healthy, polyunsaturated. Polyunsaturates - of which sunflower oil, for example, is a good source - divide into two groups of essential fatty acids (EFAs): omega-3 and omega-6.

In the typical UK diet the amount of omega-6 - good for lowering blood cholesterol and for the skin - outweighs omega-3 several times over. Ideally we should be getting more omega-3 than we are, but our bodies can't produce it, so we rely on our diets for it.

Long and short of it

There are several types of omega-3 fatty acids and they're not all equal. It's the long-chain omega-3s, EPA and DHA, that the fuss is about, and these are the ones found mostly in oily fish. They have anti-inflammatory properties (good for achy joints) and the overwhelming evidence is that they help reduce the risk of heart disease. The long-chain fatty acids also help the development of brain tissue, nerve growth and the retina in unborn babies.

Official recommendations

A portion of oily fish contains 2-3g of long-chain omega-3. The FSA recommends eating two portions of fish, one of which should be an oily fish such as sardines, mackerel or salmon, each week. It's not much, but most of us don't manage to eat even that amount - which means that many of us may be deficient in omega-3.

Whether an omega-3 supplement can make a difference to otherwise healthy and well nourished children or adults is debatable. Even where children are nutritionally disadvantaged, according to Dr Joan Ransley, nutrition researcher at the University of Leeds, omega-3 is not the most important issue - obesity is. "It is crazy to give children a supplement if they're eating a diet of junk food," she says.

Sources of omega-3

Fish oils are the best source of long-chain omega-3 fatty acids. Soya, hemp, flax and pumpkin seeds and oils, walnuts and leafy green vegetables - all healthy foods with other benefits too - contain omega-3 fatty acids, but they are the shorter-chain ones.

Our bodies can convert these into the long-chain EDA and DHA fatty acids that do most good, but not very efficiently, according to independent nutritionists. One reason that sales of organic milk have shot up is that a study found it has much higher levels of omega-3 than non-organic milk. However, these too are the shorter-chain omega-3s.

Foods with added omega-3

Spreads, juices and milk with added omega-3 - in other words artificially enriched with fish oils - are now widely available. They often play on consumers' anxieties about diet and give the impression that omega-3 is a new 'wonder food'.

Ideally diets should contain more omega-3, but you might have to eat or drink a lot of these products to meet the Government's target. For instance, drinking a glass of juice containing 20 per cent of the recommended daily intake of long chain omega-3, as some claim they contain, still means you'd have to get the rest from somewhere else, or drink five glasses of juice.

Eating well

Oily fish is undoubtedly good to eat and should be included in the diet. Eating a varied diet of fresh, unprocessed food is always better than thinking that food with supplements will make up for basic deficiencies.

Given that one portion of salmon or mackerel, sardines or fresh (not canned) tuna a week should provide enough of the necessary omega-3, consumers should make more effort to eat more oily fish - within FSA guidelines - rather than to buy (often expensive) products with added omega-3 as a form of reassurance.

DISCLAIMER: The information and advice contained in this article are intended as a general guide to healthy eating and are not specific to individuals or their particular circumstances. All content within this article is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. The BBC is not responsible or liable for any diagnosis made by a user based on the content of the BBC Food website. The BBC is not liable for the contents of any external internet sites listed, nor does it endorse any commercial product or service mentioned or advised on any of the sites. Always consult your own GP if you're in any way concerned about your health.

Updated March 2009

Recipes for oily fish

• Grilled mackerel with potato and onion mustard
• Mackerel baked in foil
• Fresh marinated tuna with butter beans
• Sardines with redcurrants
• Bandarillas
• Coriander seared tuna on pickled bean sprouts
• Home-cured herring