Effect of fiber from fruits and vegetables on metabolic responses of human subjects: fiber intakes, fecal excretions, and apparent digestibilities.

Intakes and excretions of fiber were determined for 12 men consuming controlled diets containing fruits and vegetables (high fiber diet) or fruit and vegetable juices (low fiber diet) for periods of 26 days. The fiber in the low fiber diet appeared to be mostly hemicellulose, with an apparent digestibility of 95%. Apparent digestibilities of hemicellulose, cellulose, and lignin in the high fiber diet were 88, 42, and 18%, respectively. Small amounts of uronic acids were detected in the feces, but there is no certainty that they were derived from pectin. Linear regressions indicate that fiber intakes, rather than fiber disappearance, influenced the fecal volume.