Resistant starch physiological effects

In recent years, there has been increasing interest in those carbohydrates that escape absorption in the small intestine and enter the colon, where they may have specific health benefits due to their fermentation by the colonic microflora and their effect on gut physiology. This entry considers the definition, classification, dietary sources, methods of analysis, colonic fermentation, and health benefits of both resistant starch and oligosaccharides, and compares them with those of dietary fiber. 

The main physiological effects of digestion and fermentation of resistant starch are summarized in Table 5. However, most of these effects have been observed with a resistant starch intake of around 20-30 gday , which represents from 5 to 7 times the estimated intake for the European population. 

Table 5 Physiological effects of resistant starch intake...

There has been much debate of the definition of dietary fiber and in particular whether it should include carbohydrates other than nonstarch polysaccharides. Recently, the American Association of Cereal Chemists (AACC) proposed a new definition of dietary fiber, which would include both oligosaccharides and resistant starch as well as associated plant substances. This new definition would also require complete or partial fermentation and demonstration of physiological effects such as laxation, and reduction in blood glucose or blood cholesterol. A similar approach to include beneficial physiological effects is also proposed by the Food and Nutrition Board of the US Institute of Medicine. 

Table 7 The physiological effects of resistant starch, oligosaccharides, and dietary fiber...

Physiological effect Resistant starch Oligosaccharides Dietary fiber... 

Thus, it is being increasingly recognized that oligosaccharides, resistant starch, and nonstarch polysaccharides are very similar especially in their effects on gut physiology and colonic fermentation. A comparison of their actions is summarized in Table 7. This inclusion of resistant starch and oligosaccharides in the definition of dietary fiber could have major implications for food labeling. 

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