POSTPRANDIAL LIPID RESPONSE FOLLOWING A HIGH-FAT MEAL IN RATS ADAPTED TO DIETARY FIBER

Rats were adapted to diets containing 5 g/100 g cellulose (CL), 5 g/100 g oat bran fiber (OB) or 5 g/100 g psyllium husk (Psy) for 4 wk. Following a 12-h fast, animals were either killed at 0 h (baseline) or fed 4.5 g of a test meal that provided 50% energy from fat, then killed at 1, 4 or 6 h postprandially. Fasting plasma and HDL cholesterol concentrations were lower in Psy-fed animals than in rats fed either CL or OB. Plasma triglycerides increased significantly from baseline (0 h) in all groups but did not differ among diet treatments. Increases in triglyceride content of the chylomicron/VLDL fraction occurred in the CL- and OB-fed groups and in the HDL fraction of the Psy-fed group during the postprandial period. In unfed animals the hepatic and intestinal levels of apolipoprotein A-IV mRNA were higher in the CL-fed group than in the groups fed OB and Psy. Apolipoprotein B mRNA was higher in the intestine of the OB-fed group than in the groups fed CL and Psy and had a significant gradient along the small intestine, increasing in the distal third. The results suggest that chronic consumption of fiber is less likely to modify the acute plasma triglyceride response to a fat-containing test meal than if a fiber supplement is incorporated into the meal.