Eating margarine instead of butter may not be good for you after all, scientists have warned.
For the past 50 years, we have been advised to reduce our intake of saturated animal fats, and eat more of the polyunsaturated vegetable fats found in margarine.
But now scientists in the US claim to have turned that conventional wisdom on its head, with a new analysis of a study carried out between 1966 and 1973. Some of the data had been missing for decades.
The study, conducted in Sydney, followed 458 men aged 30 to 59 who had recently had a heart attack or suffered from angina.
Spreading doubt: Butter (left) may not be more harmful to health than margarine (right), according to U.S. scientists
Half were advised to cut their animal fat consumption and replace it with safflower oil – similar to sunflower oil – and safflower oil margarine.
The results, published in the British Medical Journal, showed that those who ate more of these products were almost twice as likely to die from all causes, including heart disease.
They chose the Sydney study because it was the only randomised controlled study to look at the impact of increasing consumption of omega 6 polyunsaturated fatty acid.
Most studies of dietary interventions have involved multiple changes, but the Sydney study looked solely at omega 6.
Omega 6, the most prevalent polyunsaturated fat in most Western diets, is also known as linoleic acid.
Diners who prefer the taste of butter to margarine but don't want their health to suffer will rejoice at the findings
It is found in large quantities in vegetable oils such as corn, sunflower, safflower and soybean and in margarines made from these oils.
Once in the body, it is converted into a chemical called arachidonic acid which can trigger the release of other chemicals leading to inflammation, a leading cause of a host of chronic diseases – including heart disease.
The researchers, from the National Institutes of Health in the U.S., say their findings could have ‘important implications for worldwide dietary recommendations’.
But other scientists have criticised the results, saying they did not provide enough evidence to suggest people should change their diets.
Professor Tom Sanders, of King’s College London, said the study was ‘enormously underpowered’, of ‘little relevance to diets today’ and its findings had been refuted by recent better studies.
Professor Brian Ratcliffe, of Aberdeen University, said: ‘This paper does not provide evidence for changes to the current recommendations for a healthy diet.’
And Victoria Taylor, senior dietician at the British Heart Foundation, said: ‘Our understanding of the effect of different fats on our heart develops all the time as new research into this complex issue is published.
‘Replacing saturated fats with unsaturated alternatives is a well-known recommendation for your heart, which is based on many large and in-depth studies.
‘However, this research highlights the need for us to further understand how different unsaturated fats affect our risk of heart disease.
‘Whichever fats you use it is important to be sparing with them.’
Vegetable oils and margarine are supposed to help lower cholesterol and blood pressure and increase weight loss and improve overall health.
But they are some of the most chemically altered foods in our diets, and critics say they should not be promoted as healthy.
Read more: http://www.dailymail.co.uk/health/article-2274168/Swapping-butter-margarine-bad-health.html#ixzz2K8rwTVUv
Follow us: @MailOnline on Twitter | DailyMail on Facebook