Cardiovascular risk factors, diet and the metabolic syndrome

Abstract: The clustering of metabolic disturbances, referred to as the metabolic syndrome, is today at the centre of attention. The rationale for this focus is that the prevalence of the metabolic syndrome is increasing globally with subsequent increased risk for cardiovascular complications. A westernised sedentary life-style with bad dietary habits promotes the development of obesity, insulin resistance and other abnormalities associated with the metabolic syndrome. No uniform criteria of the metabolic syndrome exist today, but in principal, all definitions are based on the co-existence of the following atherogenic risk factors; insulin resistance, abdominal obesity, hypertension, and elevated triacyIglycerol and decreased HDL cholesterol concentrations. However, additional atherogenic risk factors have been suggested to be features of the metabolic syndrome, and dietary habits may influence many of the risk factors composing the syndrome. Against this background, we investigated the metabolic syndrome (using the NCEP/ ATPIII criteria) in a cohort of 294 healthy 63-year-old Swedish men with a range of insulin sensitivities who had completed a 7 day dietary record. Circulating measures of inflammation, oxidative stress, endothelial activity, IDL particle size distribution, oxidised LDL, antibodies against modified LDL, and advanced glycation end-products were determined as was fatty acid composition of subcutaneous adipose tissue, serum phospholipids and serum nonesterified fatty acids. Approximately 70% of the subjects had at least one component of the metabolic syndrome and ~10% had the full syndrome (3 or more risk factors). Individuals with the metabolic syndrome had elevated concentrations of proinflammatory cytokines, a predominance of small dense LDL particles, and increased endothelial activity, compared with non-affected individuals. In addition, there was a tendency towards increased antibody concentrations against modified LDL in individuals with the metabolic syndrome. However, no relationships to the metabolic syndrome were found for circulating oxidised LDL, measures of oxidative stress or advanced glycation end-products. Oxidative stress and oxidised LDL were not related to each other in these individuals. Reported dietary habits were found to be associated with LDL particle size distribution, oxidative stress and endothelial activity. High amounts of typical milk fatty acids in the diet, adipose tissue and serum were related to a more favourable LDL profile (i.e. less small dense LDL particles). Furthermore, the reported intakes of different antioxidants were negatively related to oxidative stress, but the reported intake of fat (independent of type) was positively related to oxidative stress in subjects identified as having the metabolic syndrome. Endothelial activity was positively related to the reported intake of energy and alcohol, and negatively to some dietary antioxidants. In conclusion, the present study confirmed that certain putative atherogenic risk factors might be additional features of the metabolic syndrome. In contrast, other atherogenic risk factors, also suggested as additional features, were not associated with the metabolic syndrome. Whether the absence of these relationships reflected the healthy state of our individuals or the fact that these components are not early features of the metabolic syndrome remain unclear. Interestingly, several relationships were observed between dietary components and the risk factors investigated, indicating a dietary impact on the risk of developing the metabolic syndrome and its complications.