Indigestible polysaccharides

Nowadays there is scientific evidence that, besides plant polysaccharides and lignin, other indigestible compounds such as resistant starch, oligosaccharides, Maillard compounds, and phytochemicals—mainly polyphenols—can be considered DF constituents (Saura-Calixto and others 2000). Of these substances, resistant starch is a major constituent in cereals, whereas phytochemicals are the most important such substance in fruits and vegetables. Here, we address mainly polyphenols and carotenoids associated with DF in fruits and vegetables because of the important biological properties derived from them. 

Beverages contain appreciable amounts of SDF given that a certain amount of soluble indigestible polysaccharides may pass from the solid material to the beverages during processing. 

The largest and most complex carbohydrates are the polysaccharides. They are polymers, long chains of repeating chemical units. Each individual unit is called a monomer. The monomer unit of polysaccharides is the monosaccharide, normally glucose. A typical polysaccharide contains several hundred individual monomers. Examples of common polysaccharides are starches, plant products that are major macronutrients in the human diet, and cellulose, found in plant cell walls. In the human diet, cellulose is referred to as fiber, indigestible but beneficial for normal intestinal motility. More than half of the Earth s total carbon is stored in these two polysaccharides. 

Indigestible polysaccharides are part of the dietary fiber that passes through the intestine into the feces. Because enzymes produced by human cells cannot cleave the fi-1,4 bonds of cellulose, this polysaccharide is indigestible. 

After the action of salivary and pancreatic a-amylases on dietary starch and glycogen, the carbohydrate content of the small intestine consists of newly formed maltose ingested monosaccharides dietary disaccharides, such as lactose, sucrose, maltose, and trehalose oligosaccharides, such as dextrins and maltotriose and indigestible oligosaccharides and polysaccharides, such as cellulose, agar, and other oligosaccharide dietary fibers. 

Cellulose is a polysaccharide found in plant cell walls. Cellulose forms the fibrous part of the plant cell wall. In terms of human diets, cellulose is indigestible, and thus forms an important, easily obtained part of dietary fiber. As compared to starch and glycogen, which are each made up of mixtures of a and (3 glucoses, cellulose (and the animal structural polysaccharide chitin) are made up of only (3 glucoses. The three-dimensional structure of the structural polysaccharides is thus constrained into straight microfibrils by the uniform nature of the glucoses, which resist the actions of enzymes (such as amylase) that breakdown storage polysaccharides (such a starch). 

Bulk laxatives increase the volume of the intestinal contents, stimulating peristalsis. They include indigestible polysaccharides such as cellulose (bran) and ispaghula. Osmotic laxatives increase hulk in the bowel by retaining water by an osmotic effect. They include salts containing iMorly absorbed tons (e.g. Epsom sait.s) and laetiilo.se,... 

Cellulose A linear polysaccharide made up of glucose units but indigestible for humans. Makes up plants cell walls. 

Table 1. Species of intestinal bacteria which can degrade various indigestible polysaccharides (, 10) ...

For methods of formation of oligo- and polysaccharides, see Lit.. A considerable proportion of the consumed C. is often indigestible for humans ( cellulose, dextran, lichenin), while herbivores and especially ru-... 

The major kinds of digestible carbohydrates in foods are the simple sugars (glucose and fructose), disaccharides (sucrose, maltose, and lactose), and polysaccharides (amylose and amylopectin in starch from plants, and glycogen from meat). The indigestible carbohydrates include cellulose and its derivatives, pectin (the substance that makes jam and jelly gel), and plant gums. 

The indigestible polysaccharides are collectively referred to as dietary fiber. All dietary fiber comes from plants. There is insoluble fiber, mainly from the structural cellulose parts of plants, and soluble fiber—the gums and pectins. Barley, legumes, apples, and citrus fruits are foods with a high content of gums and pectins. 

Polysaccharides are generally indigestible to humans, so their effects are not manifested in the bloodstream. However, their physical movement through the colon appears to trigger certain physiological reactions in humans, possibly due to an immune reaction via the Peyer s patches. Immunostimulatory polysaccharides are large, insoluble, extensively branched molecules often occurring in triple helix formation (Turner 1998). 

Cellulose is the main constituent of plant cell walls, where it usually occurs together with hemi-celluloses, pectin and lignin. Since cellulase enzymes are absent in the human digestive tract, cellulose, together with some other inert polysaccharides, constitute the indigestible carbohydrate of plant food (vegetables, fruits or cereals), referred to as dietary fiber. Cellulases are also absent in the digestive tract of animals, but herbivorous an-... 

Morita T, S. Kasaoka, S. Kiriyama, 2004. Physiological functions of resistant proteins proteins and peptides regulating large bowel fermentation of indigestible polysaccharide. J. AOAC Int. 87, 92-796. 

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