New evidence raises questions about the link between fatty acids and heart disease

A new study raises questions about current guidelines which generally restrict the consumption of saturated fats and encourage consumption of polyunsaturated fats to prevent heart disease. The research was published today, 18 March, in the journal Annals of Internal Medicine.

An international research collaboration led by the University of Cambridge analysed existing cohort studies and randomised trials on coronary risk and fatty acid intake. They showed that current evidence does not support guidelines which restrict the consumption of saturated fats in order to prevent heart disease. The researchers also found insufficient support for guidelines which advocate the high consumption of polyunsaturated fats (such as omega 3 and omega 6) to reduce the risk of .

Furthermore, when specific fatty acid subtypes (such as different types of omega 3) were examined, the effects of the fatty acids on varied even within the same broad 'family' – questioning the existing dietary guidelines that focus principally on the total amount of fat from saturated or unsaturated rather than the food sources of the fatty acid subtypes.

Dr Rajiv Chowdhury, the lead author of the research at the University of Cambridge, said: "These are interesting results that potentially stimulate new lines of scientific inquiry and encourage careful reappraisal of our current nutritional guidelines.

"Cardiovascular disease, in which the principal manifestation is coronary , remains the single leading cause of death and disability worldwide. In 2008, more than 17 million people died from a cardiovascular cause globally. With so many affected by this illness, it is critical to have appropriate prevention guidelines which are informed by the best available scientific evidence."

For the meta-analysis, the researchers analysed data from 72 unique studies with over 600,000 participants from 18 nations. The investigators found that total saturated fatty acid, whether measured in the diet or in the bloodstream as a biomarker, was not associated with coronary disease risk in the observational studies. Similarly, when analysing the studies that involved assessments of the consumption of total , long-chain omega-3 and omega-6 , there were no significant associations between consumption and cardiovascular risk.

Interestingly, the investigators found that different subtypes of circulating long-chain omega-3 and omega-6 fatty acids had different associations with coronary risk, with some evidence that circulating levels of eicosapentaenoic and docosahexaenoic acids (two main types of long-chain omega-3 polyunsaturated ), and arachidonic acid (an omega-6 fat) are each associated with lower coronary risk.

Similarly, within saturated fatty acid, the researchers found weak positive associations between circulating palmitic and stearic acids (found largely in palm oil and animal fats, respectively) and cardiovascular disease, whereas circulating margaric acid (a dairy fat) significantly reduced the risk of cardiovascular disease.

Additionally, when the authors investigated the effects of omega-3 and omega-6 fatty acid supplementations on reducing coronary disease in the randomised controlled trials, they did not find any significant effects – indicating a lack of benefit from these nutrients.

Professor Jeremy Pearson, Associate Medical Director at the British Heart Foundation, which helped fund the study, said: "This analysis of existing data suggests there isn't enough evidence to say that a diet rich in but low in saturated fats reduces the risk of . But large scale clinical studies are needed, as these researchers recommend, before making a conclusive judgement.

"Alongside taking any necessary medication, the best way to stay heart healthy is to stop smoking, stay active, and ensure our whole diet is healthy – and this means considering not only the fats in our diet but also our intake of salt, sugar and fruit and vegetables."

Explore further

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More information: The paper 'Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk' will be published in the 18 March edition of Annals of Internal Medicine.
Journal information: Annals of Internal Medicine

Citation: New evidence raises questions about the link between fatty acids and heart disease (2014, March 17) retrieved 18 June 2019 from
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Mar 17, 2014
Though meta-analyses are often useless or counter productive, I am glad to see a rethinking of the cardiac dietary guidelines. The low fat, polyunsaturated fat guidelines were developed over 40 years ago without appropriate study and have remained without validation studies.

Prior to developing the low fat, polyunsaturate fat guidelines, most people consumed lard and butter as their main sources of fat. Those people were not dying of cardiovascular disease.

This was an important and useful study.

Mar 17, 2014
Actually the guidelines were originally developed in spite of appropriate studies.

I found this interesting. While the program was driven by the statin debate, it talks at length about the political BS and scientific fraud involved in how the guidelines came about.

Mar 17, 2014
Thanks for the link.

So far as cholesterol goes, there has never been a valid study which showed a benefit to lowering cholesterol. Not one.

My physician keeps talking to me about cholesterol and I keep telling him that if he can produce a valid study which shows a benefit to taking statins to lower cholesterol, then I will consider it. He has not produced that study because it does not exist.

Mar 17, 2014
Actually studies do exist that show that taking statins can show benefit with respect to CVE. Just not much benefit. But there is no evidence that it is the lowering of total cholesterol that provides the benefit. It is reduction of inflammation.

Mar 18, 2014
Actually studies do exist that show that taking statins can show benefit with respect to CVE. Just not much benefit. But there is no evidence that it is the lowering of total cholesterol that provides the benefit. It is reduction of inflammation.

The Jupiter study is the only study which found a benefit to statins at all and it was rigged. The participants, to be in the study, had to have high levels of CRP (inflammation) and the benefit was strictly from statin's anti-inflammatory effect.

The drug companies needed at least one study showing a benefit of taking statins -- hence the rigged Jupiter study.

There are many drugs (and even supplements) which have an anti-inflammatory effect and which are far safer than statins and which are also cheaper. Statins can cause permanent damage and death.

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