Diet and Cardiovascular Health: Chylomicron Remnants and Their Emerging Roles in Vascular Dysfunction in Atherogenesis

With increasing recognition of the pivotal role of vascular dysfunction in the progression of atherosclerosis, the vasculature has emerged as an important target for dietary therapies. Recent studies have indicated that chronic fatty acid manipulation alters vascular reactivity, when measured after an overnight fast. However, individuals spend a large proportion of the day in the postprandial (non-fasted) state. Several studies have shown that high fat meals can impair endothelial function within 3–4 h, a time period often associated with peak postprandial lipaemia. Although the impact of meal fatty acids on the magnitude and duration of the postprandial lipaemic response has been extensively studied, very little is known about their impact on vascular reactivity after a meal. Introduction Vascular tone/reactivity/elasticity is defined as the balance between vasorelaxing and vasoconstricting mechanisms in the environment of the vascular smooth muscle cells, the muscle group which determines vascular tone. Reductions in the bioavailability of nitric oxide, an endothelialderived vasorelaxant, due to decreased synthesis, enhanced degradation and/or inactivation by an excess generation of reactive oxygen species in the subendothelial space, have been shown to contribute to endothelial dysfunction [1]. Impaired vascular reactivity/tone has been associated with the accelerated progression of atherosclerosis and serves as a marker for general vascular dysfunction [2]. Recent studies have highlighted the prognostic value of measures of vascular reactivity of both the coronary and peripheral arteries in predicting future coronary events [3]. Meal fat content, composition and vascular reactivity Evidence is emerging in the literature that mechanisms involved in the control of vascular tone are influenced by dietary factors, with dietary fat emerging as a potentially important modulator. In general, diets rich in SFAs (saturated fatty acids) have been shown to negatively affect fasting endothelial function, MUFAs (mono-unsaturated fatty acids) to be neutral or modestly beneficial, and a limited, but a convincing body of evidence indicates positive effects of long chain n− 3 PUFAs (polyunsaturated fatty acids) [4]. However, healthy individuals spend a large proportion of the day in the postprandial (non-fasted) state and the acute impact of dietary factors on postprandial vascular reactivity is poorly understood.