Dietary fatty acids and cardiovascular disease risk in observational studies
Dietary fat is a valuable component of the diet and essential for the human body. Over time it has become clear that certain types of fat(ty acids) are also potentially harmful for our health. For example, we know from intervention studies that saturated fat and trans-fat have unfavourable effects on serum cholesterol concentrations, which in turn is related to a higher risk of coronary heart disease (CHD). In general, there is scientific consensus on the harmful effects of trans-fat, but the link between saturated fat and CHD has been debated for decennia now. This debate is mainly caused by the discrepancy between the results of randomized controlled trials and the results of observational studies. Whereas the first show that a higher intake of saturated fat raises LDL cholesterol concentrations, most observational studies found no relation between dietary saturated fat and CHD risk. In this thesis, I present the results of a number of observational studies on the association between dietary fat and cardiovascular disease risk. The main focus of the thesis is on the association between saturated fat and CHD. We started by investigating whether this association depends on a number of predefined factors that were ignored in most previous observational studies, and that could potentially explain the disagreement with the results of intervention studies. Before we discuss the results of those studies in chapter 3, we discuss in chapter 2 the validity and reproducibility of a crucial assessment in nutrition research; the dietary assessment.