Saturated fats, dairy foods and health: a curious paradox?

Cardiovascular diseases (CVD) remain a major cause of death and morbidity worldwide. Dietary guidelines aim to restrict the intake of saturated fatty acids (SFA) as they are regarded as an important risk factor for CVD due to their association with increased blood cholesterol. As dairy foods are major contributors of dietary SFA, there have been guidelines to reduce consumption of these foods. However, it is now generally accepted that the effects of reducing intake of SFA are dependent on what replaces them in the diet. Reduced CVD risk has been associated with replacement of SFA with cis-polyunsaturated fatty acids (cis-PUFA) and/or cis-monounsaturated fatty acids (cis-MUFA), with replacement by carbohydrate leading to no reduction or even increased CVD risk. Most studies on the effect of diet/food on CVD risk have used total cholesterol (TC) and/or low-density lipoprotein cholesterol (LDL-C) in blood as the marker(s) of risk. However, because of potentially attenuating effects of dairy foods (e.g. effect of protein on blood lipids and blood pressure; food matrix effects on fat bioavailability), a wider range of markers is needed to more fully evaluate disease risk. Nevertheless, whilst prospective evidence shows no increase in CVD risk from high dairy consumption, it is still unclear whether replacing a proportion of SFA in dairy fat with cis-MUFA will lead to reduced CVD risk. The relatively few randomised controlled trials that have examined this using TC/LDL-C as risk markers give some indications of reduced CVD risk from consumption of milk and dairy products with modified fatty acid composition, compared with those of normal milk fat composition. The results of ongoing studies will add valuable new evidence on this issue