02 Oct Foods With Polyunsaturated Fat May Decrease Risk of Coronary Heart Disease
Jyrki Virtanen, PhD
Adjunct Professor of Nutritional Epidemiology
University of Eastern Finland
Medical Research: What are the main findings of the study?
Dr. Virtanen: The main finding was that saturated fat intake was not an independent risk factor for Coronary Heart Disease even in a population with relatively high average saturated fat intake, like in this population with middle-aged and older men from Eastern Finland. In other words, intake of carbohydrates in place of saturated fat was not associated with lower risk, not even when the quality of carbohydrates was taken into account. Only when polyunsaturated fat replaced saturated fat in the diet, was the risk of Coronary Heart Disease, especially Coronary Heart Disease mortality, lower. In fact, also replacing trans fat or carbohydrates with polyunsaturated fat was associated with lower risk. The associations were similar with both n-6 and n-3 polyunsaturated fatty acids.
Trans fat intake was not associated with the Coronary Heart Disease risk, but that is most likely explained by the low intake of trans fat in Finland already in mid-1980s.
We also investigated the associations of the fatty acid intake with carotid artery atherosclerosis, and the results were generally similar to the findings with incident Coronary Heart Disease events.
Medical Research: What was most surprising about the results?
Dr. Virtanen: The surprising finding was that higher monounsaturated fat intake was associated with higher risk of Coronary Heart Disease. However, this should not be interpreted as suggesting that olive oil, which contains high amounts of monounsaturated fat and which is an important part of the traditional heart-healthy Mediterranean diet, would be to blame for these findings. The use of olive oil was very low in this study population.
At the moment we do not have an explanation for this finding, but we are continuing the investigations with different monounsaturated fat sources in the diet in this study population to see if certain foods or food groups that are major sources of monounsaturated fat could explain the higher risk with higher monounsaturated fat intake.
Medical Research: What should clinicians and patients take away from your report?
Dr. Virtanen: In order to reduce the risk of Coronary Heart Disease, saturated fat should be replaced with polyunsaturated fat. Good sources of polyunsaturated fat are, for example, fish, vegetable oils and nuts.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Virtanen: The research should now focus more on foods and food groups instead of nutrients, because we eat foods, not nutrients. There is some evidence that, for example, different saturated fat sources have a different effect on the risk factors and incidence of Coronary Heart Disease. Therefore, it is possible that Coronary Heart Disease risk cannot be predicted simply on the basis of the fatty acid profile of a food, for example the content of saturated fat.
Dietary Fatty Acids and Risk of Coronary Heart Disease in Men: the Kuopio Ischaemic Heart Disease Risk Factor Study
Jyrki K. Virtanen, Jaakko Mursu, Tomi-Pekka Tuomainen, and Sari Voutilainen
Arterioscler Thromb Vasc Biol. 2014;ATVBAHA.114.304082published online before print September 25 2014, doi:10.1161/ATVBAHA.114.304082