Bulletin

Issue: May 2005

Research in Action

Omega-3 fatty acids: yes, but how much and when?

The world of nutritional science agrees there are numerous benefits from consuming Omega-3 fatty acids.

Such organisations as the American Heart Association and the Heart Foundation of Australia recommend eating fish, particularly fatty fish such as mackerel, herring, sardines, certain types of tuna and salmon, at least twice a week.

Such fish are high in two kinds of Omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

In addition, some food like soybeans, canola, walnut and flaxseed, and their oils, contain a shorter Omega-3 fatty acid, alpha-linolenic acid (ALA). Enzymes in the body metabolise the ALA into the longer Omega-3 fatty acids, EPA and DHA.

When, in what quantities and in what form should
Omega-3 fatty acids be taken? And is there a point when it could be harmful like the closely related saturated fat?

(Saturated fat comes from animal fats and is found as hidden fat in many of the processed foods we in the Western world consume in high quantities).

The answers to these questions may soon be known. An international team, led by La Trobe University behavioural neuro-scientist, Dr Richard Weisinger, recently received a three-year $277,000 grant from the National Health and Medical Research Council (NHMRC) to find answers to these basic questions.

Dr Weisinger, a NHMRC Senior Research Fellow, and psychologist turned neuro-scientist, heads a team that includes Professor Andrew Sinclair (RMIT), Dr Michael Mathai, his son, Dr Harrison Weisinger, and Dr Jennifer Wilson-Berka (University of Melbourne), Dr Leigh Ackland and Dr David Cameron-Smith (Deakin University), Drs Laslo Puskas and Klara Kitajki (Hungarian Academy of Sciences) and Dr Anura Jayasooriya (University of Peradeniya, Sri Lanka).

Dr Weisinger said that his team is trying to ascertain the exact role that ALA, EPA and DHA play in the prevention and perhaps treatment of high blood pressure, a major risk factor for cardiovascular disease.

In Dr Weisinger’s work with laboratory rats, putting a pregnant healthy female rat on a low Omega-3 fatty acid diet, resulted in deficient milk and deficient pups that were hypertensive, that is they had high blood pressure as adults.

‘Providing the Omega-3 fatty acid after the peri-natal period, the first several weeks of life, did not stop the development of the hypertension. We are looking for the mechanisms that may be responsible for this.

‘We humans evolved as hunter gatherers with a fatty acid diet in which Omega-3 and Omega-6 fatty acids existed in roughly equivalent amounts,’ Dr Weisinger said.

‘But in modern Western society we now consume between 10 to 25 times more Omega-6 than Omega-3 fatty acid. Omega-6 fatty acids are found in animal fats and oils, most vegetable fats and oils and dairy fats. This becomes a major problem because both Omega-6 and Omega-3 fatty acids compete for the same metabolic enzymes, and the amount of EPA and DHA produced from ALA is severely reduced,’ Dr Weisinger said.

‘Professor Sinclair and his group are trying to determine how to overcome the rate limitations on production of EPA and DHA in humans. This problem is greatly alleviated by the consumption of fish or the reduced consumption of Omega-6 fatty acids. Unfortunately, the Western diet is very low in fish and very high in Omega-6 fatty acids.’

Based on Dr Weisinger’s work with laboratory rats, it is clear that Omega-3 fatty acids are important to pregnant and nursing mothers and it is hoped that recommendations regarding the amount and timing of its intake can be provided soon.

Dr Weisinger is supervising two PhD students working in his laboratory on the project, Ms Nora Chen and a medical doctor, Dr Jian Shi. •

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