Hypocholesterolemic action of dietary fiber unrelated to fecal bulking effect.

Twenty-two healthy volunteers took approximately 20 g/day of concentrated dietary fiber from either carrot, cabbage, apple, bran, or guar gum or 31 g from pectin, added for 3-week periods to controlled diets. Total serum cholesterol fell by 13% on both guar and pectin (P less than 0.01) with no significant change in high density lipoprotein cholesterol. Over the 3-week supplementation period, the other fibers were without effect with the exception of carrot, where both control and test high density lipoprotein levels fell (P less than 0.05 and less than 0.01, respectively). If, however, the 3rd week of the control was compared with the 3rd test week, the values for total cholesterol were 7% lower after apple (P less than 0.02) while after carrot the high density lipoprotein cholesterol level was 10% lower than the control (P less than 0.01). No significant change was seen in serum triglyceride or body weight either as judged by differences over the 3-week periods or by comparing test and control values at 3 weeks. Comparison of stool weights obtained in this study indicate that the fecal bulking action of dietary fiber is independent of its hypocholesterolaemic effect.