OMEGA-3 AND HEALTH RESEARCH

Changes in our eating habits have created an imbalance between the levels of Omega-3 in our diet and Omega-6 - both of which are polyunsaturated fatty acids - and this imbalance is gradually being recognised as a major contributor to health problems¹.

While the amount of Omega-6 that we eat has risen, Omega-3 levels have fallen. Ideally, intake of Omega-6 should be no more than four or five times more than Omega-3s. Today in Britain, it is seven or eight times more, while in some countries such as America and Australia, it can be 10 or 12 times more¹.

Changes in the popularity of different foods are to blame. Our consumption of oil rich fish, which are high in Omega-3 has decreased over the last century, while our intake of white fish such as cod and haddock, which are very low in Omega-3, has increased. At the same time our consumption of foods rich in Omega-6, such as polyunsaturated margarine, sunflower and corn oils, has increased¹.

The Department of Health, through its Committee on the Medical Aspects of Food Policy (COMA) says we should all be eating one to two portions of fish a week - one of which should be an oil rich fish such as trout to boost our levels of Omega-3 fatty acids. A weekly intake of 1.5g a week is advised. An average portion of grilled trout (flesh only) is 155g, which provides 1.838g of Omega-3¹.

Oil rich fish, which have an abundance of Omega-3 long chain fatty acids include trout, herring, mackerel, kippers, pilchards, sardines, salmon (tinned tuna is not a good source). White fish, such as cod, haddock, plaice and shell fish contain very low levels of Omega-3.

OMEGA-3 AND CORONARY HEART DISEASE

Oil rich fish such as trout provides the Omega-3 polyunsaturated fatty acids which are believed to help provide protection against coronary heart disease.

Research indicates that they may lower plasma triglyceride (blood fat) levels. Raised triglyceride levels are of particular importance when associated with high cholesterol levels².

They are also thought to reduce blood clotting by preventing the blood platelets from sticking together².

Studies carried out on Eskimos, who traditionally eat large amounts of oil rich fish, demonstrated that they have a low blood clotting tendency, longer bleeding times (in response to a cut) and a low incidence of coronary heart disease. Other big fish eating communities, such as Japanese fishing villages, also show a reduced tendency for blood to clot¹.

A two-year study was carried out in Wales (Burr et al., 1989) of over 2000 men who had just recovered from their first heart attack and who were therefore at risk of a second attack. The men were randomly allocated to a number of dietary groups, one of which was asked to eat at least two portions per week of oil rich fish. At the end of the two year period, it was found that although there was a similar number of heart attacks in each group, there were 29 per cent fewer deaths in the fish eating group. Hence, eating oil-rich fish regularly seems to reduce the risk of death after a heart attack rather than preventing a second heart attack occurring¹.

THE IMPORTANCE OF OMEGA-3 IN INFANT DEVELOPMENT

Recognition that the long chain DHA derivatives of Omega-3 fatty acids are a major constituent of the human brain and retina has resulted in considerable research in the past decade, particularly in relation to the needs of new born babies¹.

There is accumulating evidence to demonstrate the importance of Omega-3 in the development of the unborn child in the womb and the newly born infant. Required throughout pregnancy, Omega-3 is particularly important during the last three months and during early infancy for the proper development of the eyes, the brain and nerves.

A large part of the baby's brain growth takes place during the last three months of pregnancy. Babies born too early run the risk of not getting all the Omega-3 needed to complete this process. Scientists stress the value of breast feeding as breast milk naturally contains a good supply of Omega-3s.

Children who were breast fed have often been shown to perform better in tests of development or cognition, verbal ability or school performance (Morley 1998). However, some of these studies did not take contributory factors into consideration.

OMEGA-3 AND RHEUMATOID ARTHRITIS

The main long-term problem in rheumatoid arthritis is progressive erosion of the cartilage in joints, leading to irreversible destruction.

Oil rich supplements have been shown to alleviate some of the symptons, producing beneficial changes in levels of fatigue, swollen and tender joints, grip strength and mobility. The most valuable effects could be to enable sufferers to reduce their use of pain-relieving drugs, which sometimes have severe side effects¹.

OMEGA-3 AND DEPRESSION, SCHIZOPHRENIA AND ALZHEIMER'S

There is a limited amount of data upon which it has been hypothesised that either a poor intake of Omega-3 or an imbalance in the Omega-3 and Omega-6 ratio might be associated with the incidence of various manifestations of abnormal cognitive function.

Much of this speculation is based on findings of low levels of Omega-3 acids in cell membranes of subjects with depression, schizophrenia and Alzheimer's disease. It remains to be shown, however, whether this finding is causal or whether it is associated with changes in dietary patterns that have resulted from illness'.

1. British Nutrition Foundation
2. British Heart Foundation

British Trout Association, The Rural Centre, West Mains, Ingliston EH28 8NZ
Tel: 0131 472 4080    Fax: 0131 472 4083     E-mail: mail@britishtrout.co.uk