ABSTRACT
Gidley and colleagues have investigated the molecular structure of resistant starch in great detail using a combination of physicochemical techniques. Resistant starch behaves functionally as dietary fiber because it resists digestion by the enzymes of the stomach and small intestine. The physiological functions of dietary fiber change as it progresses through the gastrointestinal tract. The polysaccharides of which dietary fiber is mostly composed are complex structures in which the geometry of the linkage between monomer units largely defines physical properties. The cholesterol-lowering effect of dietary fiber, it is suggested, can, at least in part, be explained by adsorption of bile acids to fiber in the small intestine. Many of the texture-modifying agents used in the food industry are nonstarch polysaccharides and as such constitute dietary fiber. A study comparing breakfast cereals suggested that the energy required to break the product down into small pieces increases with its dietary fiber content.
