Dietary fiber and lipoprotein metabolism in the genetically obese Zucker rat.

The present investigation was designed to examine the influence of dietary fibers with differing soluble fiber compositions upon the metabolism of lipids in a hyperlipemic animal model, the Zucker fatty rat. The response to fiber was examined using a diet supplemented with cellulose, oat bran, or pectin which have a soluble/insoluble fiber ratio of 0:100, 33:66, and 100:0, respectively. These fibers provided 10% of the total diet weight; the control diet contained no fiber. A rapid increase in plasma triglyceride concentration was observed in all animals given fiber-supplemented diets in correlation with the increased carbohydrate content of the defined diets relative to the prestudy diets. This increase in plasma triglyceride was due to increased production of triglycerides with no change in the rates of clearance. The plasma total cholesterol levels were relatively constant on all diets. However, after 7 weeks on the pectin-supplemented diet, rats showed a 39% elevation in HDL and a 44% reduction in LDL concentration. This diet also resulted in reduced weight gain, in spite of a caloric intake equivalent to the control diets. Our data suggest that the ability of dietary fiber to alter plasma lipoproteins might be predictable from the soluble fiber composition or the pectin content of a given dietary fiber in this model of genetic endogenous hyperlipemia.