Last update:
01-Dec-2010

Despite the fact that the presence of fibers in the diet has long been recognized, their role in the prevention of various diseases of the gastrointestinal tract still breeds controversy, mainly because a high-fiber diet is characterized by poor digestibility. Soluble fibers, such as pectins, guar and ispanghula, produce viscous solutions in the gut that cannot be easily absorbed and are passed along the different parts of the gastrointestinal tract. Insoluble fibers pass largely unaltered through the gut, leading to bulky stools. The difference in the degree of fermentation of the fibers by the intestinal flora leads to an increase in the volume of gases produced in the colon, which causes symptoms of discomfort in many patients. This is a review of the physiology of ingestion and defecation of dietary fibers and their impact on chronic constipation, irritable bowel syndrome and colorectal neoplasia. From the findings of this review, a strong case on the protective effect of dietary fibers cannot be safely made. Clinicians should weigh the advantages and disadvantages of a high-fiber diet on an individual basis before recommending it; more studies need to be conducted in this field.

Key words: Adenomatous polyp, Colorectal neoplasia, Constipation, Dietary fibers, Irritable bowel syndrome.