|
Since 1979, when Zilversmit observed that chylomicrons, and especially their remnants, which are the lipoproteins responsible for the transport of dietary fat in the circulation, can enter the arterial wall and play a role in the development of atherosclerosis, several studies have been carried out looking at the effects of postprandial lipemia on lipoprotein metabolism and risk factors of coronary heart disease. This is due to a decrease in the clearance of postprandial chylomicron- and VLDL-triglycerides and the increase in atherogenic remnants synthesis, which can enter the arterial wall and increase cholesterol deposition and foam cell production.
The Mediterranean Diet is characterized by a high consumption of fruits and vegetables but the effects on postprandial lipemia are mainly due to the consumption of fish and olive oil. In particular, n-3 fatty acids, from fish oils, is now well known that they exhibit hypotriglyceridemic properties both in the fasting and in the postprandial state. Their major action is through the decrease in VLDL synthesis in the liver, and some believe that they also increase lipoprotein lipase activity. Studies have also been carried out looking at the effects of olive oil and monounsaturated fatty acids on postprandial triglyceride responses and they observed that triglyceride levels are lower following a meal containing olive oil than a meal containing butter. However, these findings are not overwhelmingly confirmed. In addition, Cretans whose background diet is rich in olive oil respond different to a meal containing fat than subjects from Northern Europe and this response may be cardioprotective. Mechanisms responsible for this cardioprotective potential include production of large chylomicrons in the enterocyte, which then clear faster by lipoprotein lipase and decrease in factor VII activity which plays a significant role in the coagulation cascade.
Conclusively, the cardioprotective properties of the Mediterranean Diet may be partly through the fish and olive consumption, which can decrease the magnitude of postprandial lipemia. |
