In general, viscous fibers such as gums, gels and mucilage have small intestinal effects such as decreased absorption of nutrients, flattening of blood glucose and insulin levels post-prandially, and reduction in serum cholesterol (by increasing fecal bile acid losses). However, in the large intestine, these soluble fibers are utilized by the normal flora to produce gases and some short chain fatty acids (SCFA), and so in contrast to particulate fiber such as grain husk, they have no function in fecal bulking.
Psyllium husk is unique in this context in that it produces the benefits associated with soluble fiber in the small intestine but is not well utilized by the colonic flora and so acts also as a fecal bulking agent. In this way, it is the perfect intestinal purifier and when combined with other nutrients, produces the best means of detoxification of the gastrointestinal tract.