The postprandial state and risk of cardiovascular disease

Metabolism in man is regulated by complex hormonal signals and substrate interactions, and for many years the clinical focus has centred on the metabolic and hormonal picture after an overnight fast. More recently, the postprandial state, i.e. 'the period that comprises and follows a meal', has received more attention. The oral glucose tolerance test (OGTT), although highly non-physiological, has been used largely as a model of the postprandial state. Epidemiological studies have shown that, when 'impaired', oral glucose tolerance is associated with an increased risk of cardiovascular disease. Postprandial hyperlipidaemia has been investigated more recently in epidemiological, mechanistical and intervention studies, most of which indicate that high postprandial triglyceride levels, and particularly postprandial rich triglyceride remnants, constitute an increased risk for cardiovascular disease. Recent studies have shown that excessive postprandial glucose excursions are accompanied by oxidative stress and, less well known, activation of blood coagulation (increase in circulating D-dimers and prothrombin fragments). The mechanisms through which increased postprandial glucose levels and lipid concentrations may damage endothelial cells on blood vessel walls appear to be complex. These mechanisms include the activation of protein kinase C, increased expression of adhesion molecules, increased adhesion and uptake of leucocytes, increased production of proliferative substances such as endothelin, increased proliferation of endothelial cells, increased synthesis of collagen IV and fibronectin, and decreased production of nitric oxide (NO). In conclusion, the 'postprandial state' cumulatively covers almost half of the nycthemeral period, and its physiology involves numerous finely regulated motor, secretory, hormonal and metabolic events. Epidemiological and mechanistical studies have suggested that perturbations of the postprandial state are involved in cardiovascular disease. Correcting the abnormalities of the postprandial state must form part of the strategy for the prevention and management of cardiovascular diseases, particularly those that are associated with diabetes mellitus.