12 January - 20 June 2016

Some omega-6 polyunsaturated fats linked to higher death rates

20 Feb 13

A recent study published in the British Medical Journal by Ramsden et al has suggested that people who favour eating certain omega-6-polyunsaturated fats over animal fats (consistent with the recommended switch from butter to margarines and spreads) have higher death rates than those who favoured the animal fats.  Researchers in the USA and Australia have conducted a second analysis of a randomised controlled trial which was performed in Australia between 1966 and 1973.  The initial trial investigated whether replacing saturated fats in the diet with safflower oil which provides high levels of linoleic acid reduced the risk of death from any cause in men with premature coronary heart disease; however it only investigated deaths from all causes.  This current study uses the same dataset to investigate whether eating more safflower oil affected the risk of death in people with cardiovascular or coronary heart disease and whether an increased intake of polyunsaturated fatty acids or saturated fatty acids were associated with deaths from CVD and CHD.  The study recruited 458 men aged 39-50, who had suffered a heart attack, an episode of coronary insufficiency or angina.  One group were given instructions to increase their polyunsaturated fat intake by using safflower oil containing 74.6g per 100g of omega 6 linoleic acid and decrease saturated fats to around 15 % and 10% respectively of their total energy, whilst the other group formed a control.  Blood samples were taken at set intervals over a period of years and levels of triglyceride and cholesterol were measured.  A correlation was found between intervention and higher rate of death.  Overall an increase just 5% of food energy from linoleic acid predicted a 35% higher risk of cardiovascular death and a 29% increase in mortality.  Contrary to previous findings, it suggests that not all polyunsaturated fatty acids are good for the heart.  The researchers point out that much more is now known about different PUFAs than in the 1960’s, and in particular that linoleic acid (n-6) is not as beneficial as the n-3 PUFAs such as eicosapentaenoic and docosahexaenoic acids. However, experts point out that the study has limitations and a limited scope.  There is no guarantee that this pattern would hold for the population in general, nor in fact for all different vegetable oils.

RSSL's Lipids Laboratory, part of the Investigative analysis team has expertise in all aspects of fat analysis and fatty acid profiling including the determination of CLA.  For information on the lipid profile of your product please contact Customer Services on Freephone 0800 243482 or email enquiries@rssl.com.

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