Effects of dietary fats on blood lipids: a review of direct comparison trials

Saturated fat has been demonised as a dietary culprit in heart disease due to its ability to raise low-density lipoprotein cholesterol (LDL-C), whereas omega-6 polyunsaturated fatty acid (PUFA) has been regarded as heart healthy due to its ability to lower total and LDL-C. And replacing saturated fat with omega-6 has consistently been found to lower total cholesterol and LDL-C levels.1 2 This has been the cornerstone for the belief that the omega-6 PUFA linoleic acid is heart healthy. However, the changes in LDL-C do not take into account the overall changes in the entire lipoprotein profile. For example, saturated fat appears to decrease small-dense LDL (sdLDL) and increase large buoyant LDL.3 As a high concentration of sdLDL and a low concentration of large buoyant LDL is associated with an increased risk of coronary heart disease (CHD),4 saturated fat may not necessarily increase the risk of CHD. Furthermore, compared with LDL-C, sdLDL (and oxidised LDL) seem to have a greater impact on atherosclerosis and cardiovascular disease.