Previous research which has promoted polyunsaturated vegetable fat such as margarine as a healthier alternative to butter has been quashed by a group of leading US scientists.

The new research findings led by Professor John M Davis (et al) at the National Institute of Health in the United States and just published in the British Medical Journal,  has found that eating margarine instead of butter can double the risk of heart disease and heart attack.

The US researchers analysed a previous study from 1966 and 1973 conducted in Sydney, Australia, because it was the only controlled study that had focused on one polyunsaturated fat, omega 6. The Sydney study analysed 458 men aged from the ages of 30 to 59 who had previously suffered from a heart attack.

Half of the men in the study were given no dietary advice, while the other half were advised to swap from butter and to increase their polyunsaturated fat intake by 15 per cent of their total energy consumption over a three year period.

The re-investigation into the earlier study found that the body converts polyunsaturated fat such as omega 6 into arachidonic acid, which can “spur inflammation” – a leading cause of heart disease.

Leading international nutritional expert, Emeritus Professor of medicine at Australia’s Monash University, Dr Mark Wahlqvist, told the Australian Broadcasting Corporation’s PM program yesterday that earlier researchers “didn’t want to see” the negative link between polyunsaturated fat and heart health.

“The theory about the link between polyunsaturated fatty acids and health outcomes was that it would be favourable, because the cholesterol dropped. Because the cholesterol dropped, people didn’t want to believe that the lowering of the cholesterol would not have improved coronary mortality,” Professor Wahlqvist said.

“But it didn’t and for years the National Heart Foundation and other expert committees have encouraged the view that it was favourable when it was actually unfavourable,” he added.

Professor Wahlqvist said that experts had also made the mistake of telling people to avoid eating many other healthy foods, such as eggs.

“I think it’s a serious question, what was going on in the minds of the investigators at the time, what was going on in the formulation of policy, what was going on with the relationship between the food industry and the medical profession and medical science at the time,” Professor Wahlqvist added.

Omega 6, which is also referred to as Linoleic acid, is commonly found in vegetable oils such as corn, sunflower and soybean and is the most common polyunsaturated fat now used in Western culture for margarine.

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