September 23, 2015

expert reaction to study investigating industrially-produced and naturally-occurring trans fats and heart health

Publishing in the European Heart Journal a group of researchers have described their work examining a possible link between trans fatty acids and mortality, reporting that naturally occuring trans fats were associated with reduced risk of death while no increased risk was seen with industrially produced trans fats.

Prof. Ian Givens, Professor of Food Chain Nutrition and Head of Food Production & Quality, University of Reading, said:

“This study provides encouraging evidence that attempts to reduce levels of industrial trans fats in the European diet in recent years have been successful. It finds that among the heart patients who took part in this study in Germany, the levels of trans fats within blood cells were much lower than similar measurements in the US – where dietary trans levels are higher than in Europe.

“These low levels may explain why no relationship was found between trans fats and any subsequent diseases, such as heart disease, in those taking part. It is curious that the study authors do not seem to have measured elaidic acid, the industrial trans fatty acid considered to do the most damage. This may just be because levels were so low they could not find any, but the paper doesn’t say.

“The study also suggests there may be some beneficial effects of trans fats from ruminant animals, such as meat and dairy produce. It strengthens the possibility that either the trans fats in these foods, or some other components of meat and dairy, are good for your health.”

Dr Tim Chico, Reader in Cardiovascular Medicine / consultant cardiologist, University of Sheffield, said:

“This study inadvertently runs the risk of misinforming the public about the risk of heart disease and transfats.

“Transfats have been strongly linked to an increase in the risk of narrowings in the arteries of the heart, which can then cause angina and heart attack. However, even without eating transfats we can get heart disease from other causes; smoking, high cholesterol, high blood pressure, lack of exercise and other dietary factors are also very important.

“It is important to be aware that none of the patients in the current study were healthy; all were undergoing investigation for possible heart disease and nearly 80% were indeed found to have heart disease. This means this study cannot tell us whether or not eating transfats is associated with an increased risk of heart disease, it just means it is possible to get heart disease without high levels of transfats in the diet.

“The fact that transfat levels did not predict mortality in the study may be because once the patients were known to have heart disease they were treated appropriately with statins and other medications to lower the risk of further heart problems.

“My advice remains the same; whether or not you are healthy or already have heart disease you should eat a healthy diet (rich in vegetables, nuts, seeds, and olive oil) and avoid processed foods that may contain transfats and other unhealthy ingredients.”

Prof. Tom Sanders, Professor emeritus of Nutrition and Dietetics, King’s College London, said:

“The limitation of this study is that the measurements of trans fatty acids were made in red blood cells on samples collected over fifteen years ago at a time when intakes of industrial trans fatty acids started to be removed from the European food chain. This would diminish the size of any adverse effect of industrial trans fatty acids.

“This study can only report associations and cannot show causal effects so it is questionable to suggest that higher levels of trans palmitoleic acid (a component of naturally occurring ruminant trans fatty acids) could lower risk. This association may be because higher intakes of milk products, especially yoghurt and milk, are associated with lower risk.

“Another possibility is that the results are confounded by socioeconomic status with the poorer groups consuming more industrial trans fats and the richer consuming more dairy products. When comparing studies in Europe with those in USA, it is important to recognise that different oils and processes are used.”

Ms Victoria Taylor, Senior Dietitian at the British Heart Foundation, said:

“Trans fats are associated with raised LDL cholesterol levels, a risk factor for heart and circulatory disease, and the findings of the study continue to support this.  In the UK we already consume, on average, less than the 2% recommended maximum of our food energy from trans fats. Our intakes have reduced mainly due to a reduction in industrially produced trans-fat as a result of reformulation by the food industry. This means that most of our intake comes from natural sources like meat and milk. Although it may be the case that not all trans fats behave in the same way, this does not mean that we should be eating more than we are now or that our recommendations necessarily need to change. Additional research is needed, as well as consideration of any changes in the context of the diet as a whole to ensure a benefit to our overall risk of heart and circulatory disease.”

‘Trans fatty acids and mortality in patients referred for coronary angiography: the Ludwigshafen Risk and Cardiovascular Health Study’ by Marcus E. Kleber et al. published in the European Heart Journal on Wednesday 23 September 2015. 

Declared interests

Prof. Ian Givens: Ian Givens has received dairy and health related research funding from BBSRC/DRINC, MRC, charity and industry.

Dr Tim Chico: “I’m a committee member and Treasurer of the British Atherosclerosis Society, a registered charity established in 1999 with the aim of promoting UK atherosclerosis research.”

Prof. Tom Sanders: “I was a member of the FAO/WHO Joint Expert Committee that recommended that TFAs be removed from the human food chain. I have previously acted as a member of the Global Dairy Platform Scientific Advisory Panel and I am a member of the Programme Advisory Committee of the Malaysian Palm Oil Board. In the past I have acted as a consultant to Archer Daniel Midland Company and received honoraria for meetings sponsored by Unilever PLC. My research on fats was funded by Public Health England/Food Standards Agency.”

None others received.