Macronutrient intake and modulation on chylomicron production and clearance
Résumé
The extent and kinetics of postprandial changes are highly variable and are modulated by numerous factors including diet, lifestyle conditions, genetic background and pathological conditions. This review focuses on dietary factors affecting postprandial chylomicron and lipoprotein metabolism in humans. The first key step in the process is fat digestion within the stomach and small intestine which can be modulated by fat and dietary fiber amounts and types. The second key step is intestinal absorption per se. The uptake and secretion of absorbed nutrients in chylomicrons is affected by numerous factors, including nutrients themselves. The amount of dietary triglycerides as well as the nature of fatty acids ingested from habitual diet or present in a test meal modulates the extent of chylomicron and plasma triglyceride levels postprandially. The amount of dietary cholesterol also modulates the extent of postprandial chylomicron and plasma triglycerides. Other nutrients can alter the postprandial occurrence of chylomicrons such as proteins, alcohol, carbohydrates or fibers. Addition of glucose and more markedly fructose, to a fat test meal increases the accumulation of chylomicrons, as does a high-glycemic index meal. In contrast, some sources of dietary fibers such as oat bran noticeably decrease the occurrence of chylomicron postprandially. Overall, changing the habitual dietary pattern, for instance from a Western-type diet to Mediterranean-type one, can in turn alter the postprandial response of the subjects. The last step in postprandial lipid metabolism is clearance from plasma through combined lipolysis processes and tissue uptake of chylomicron remnants. Both the processes can also be modulated by the nutrients. Because most day-time is usually spent in a postprandial state, the link between dietary patterns and cardiovascular health or risk is clearly mediated by the secretion and clearance rates of chylomicrons in the circulation