Cereal fibers: Impact on gut microbiota and health.
G. C. FAHEY (1). (1) University of Illinois at Urbana-Champaign, Urbana, IL, U.S.A.
Fibrous carbohydrates, lignin, and resistant starch are key components of whole grains. They contribute to human health in a variety of ways to include modulation of the gut microbiota toward a more healthful community. They serve as substrates for the large bowel microbiota, resulting in production of short-chain fatty acids (SCFA) that lower gut pH. This pH-lowering effect, in itself, selects for a more healthy microbiota at the expense of the less healthful, or pathogenic, microbiota. Fermentable components of whole grains may have prebiotic activity, and they contribute to the reduction in concentrations of toxic metabolites such as ammonia, indoles, phenols, and amines that result from protein fermentation in the gut. Whole grains are made up of many important bioactive components that act synergistically to provide health benefits to the host. Fiber is just one of these components, and it is sometimes difficult to differentiate the effect of fiber from the effects of the other bioactives. Nevertheless, it is important to have detailed fiber compositional data on each whole grain as specific fiber components have a critical influence on composition and activity of the large bowel microbiota, thus affecting production of acetate, propionate, and butyrate, the balance of which is crucial to the maintenance of gut health. Of paricular interest are the major butyrate-producing bacteria such as <i>Roseburia</i> spp. and the <i>Eubacterium rectale</i> group. In this presentation, the fiber profiles of select whole grains will be reported and linked to their effects on select characteristics of the large bowel microbiota.
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