Fiber intakes, stool frequency, and stool weights of subjects consuming self-selected diets

Neutral detergent fiber (NDF) contents of duplicate collections of food consumed by 29 men and women were determined for 7 days four times during the year. The ratio of analyzed NDF to calculated crude fiber intakes was approximately 2. Although mean NDF intake was 7.7 g/day for females and 9.5 g/day for males, the majority of the subjects had NDF intakes of from 4 to 9 g/day. Fiber-containing foods consumed with the greatest frequency were vegetables. NDF intakes were greater in the winter than in the spring and summer. Caloric and total carbohydrate intakes, number of stools, and fecal weights were greater for the males than for the females. Fecal weights were significantly correlated with caloric intake, NDF intake, and number of stools. It is suggested that the insoluble fiber measured by the NDF method is likely to be better correlated with fecal weight than the total dietary fiber which includes soluble fibers.