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The role of human gut microflora in health and nurition |
G. R. GIBSON, School of Food Biosciences, Univ. of Reading, Whiteknights, PO Box 226, Reading, RG6 6AP, United Kingdom The human large intestine contains a vast array of microorganisms, thought to represent the majority of all cells in the body. The nutritional, biological and clinical importance of bacteria resident in the gut is becoming increasingly recognised. Although it is known that many disease states involve bacterial metabolism, the human gut microflora may also be considered as relevant to an improvement in host health and welfare. Gut bacteria carry out a multi-disciplinary processes known as fermentation, where dietary and indigenously produced residues are metabolised to a variety of different end products. The numerically predominant (culturable) anaerobes in the gut are Gram-negative rods belonging to the genus Bacteroides. Other groups, which have hitherto been identified as numerically predominant include bifidobacteria, clostridia, eubacteria, lactobacilli, Gram-positive cocci, coliforms, methanogens and dissimilatory sulphate-reducing bacteria. It is thought that several hundred different bacterial species are present in the human large intestine. The principal substrates for colonic bacterial growth are dietary carbohydrates, such as resistant starch and non-starch polysaccharides, which have escaped digestion in the upper gastrointestinal tract. Whilst the products of gut proteolysis may be generally thought of as toxic towards host health, those of saccharolytic digestion may be considered to be benign and in some cases can contribute positively. Generally, the absorption of short chain fatty acids and their systemic metabolism may increase energy gain for the host. Moreover, butyric acid is a preferred fuel for colonocyte function. On the contrary, debilitating intestinal disorders such as inflammatory bowel disease and colonic cancer are thought to have a bacterial involvement. This presentation will overview how the gut flora can influence human health, targeting specific pathogens, and how dietary carbohydrates may improve the microbiota composition.
Session 7, Resistant starch: A food ingredient with significant physiological and health benefits
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