Doctor of Philosophy (PhD)
School of Nutrition and Food Sciences
Resistant starch (RS) increases beneficial gastro-intestinal bacterial populations simultaneously increasing short-chain fatty acids (SCFA) such as butyrate. Butyrate acts as energy source for epithelial cells of colonic mucosa which stimulates intestinal cell proliferation and has been implicated as important in reducing obesity, diabetes and cancer. The Lactobacillus spp, Bifidobacterium spp, Bacteroides thetaiotaomicron, Clostridium cluster IV and Clostridium cluster XIV are mainly involved in the production of butyrate by fermenting RS in the large intestine. With age there is a decline in these gut bacteria, but in the present study RS and diet restriction both enhanced the bacteria involved in butyrate production. In addition, RS reduces body fat in some types of obesity but not all. For example, RS reduced body fat in an endocrine model of obesity caused by ovariectomy (OV). In this study RS significantly increase bacterial populations involve in butyrate production. However, in high fat diet induced obesity the results were different. The high fat diet (41% dietary energy) prevented fermentation of RS and reduced bacterial populations in the ceca compared to a low fat diet (18% dietary energy). The RS failed to reduce obesity in these rodents fed a high fat diet while increasing Bacteroides group population. To follow up these studies and determine if type of fat was important in directly altering gut fermentation, an in-vitro fermentation model of rat large intestine was used. Both Corn oil and Lard reduced bacterial populations which are involved in fermentation of RS. However, if the fat used was fish oil there were no negative effects on the fermentation of RS or the bacterial population. These studies illustrate the need to control the type of fat when studying the effects of prebiotics or other sources of resistant starch. With the age Bifidobacterium spp, Bacteroides spp, Clostridium cluster IV and Clostridium cluster XIV decreased both calorie restricted diet and RS diets were able to improve these bacterial populations.
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Senevirathne, Reshani Nisansala, "Effect of Resistant Starch on Microbial Content of the Intestinal Tract" (2010). LSU Doctoral Dissertations. 2717.
Janes, Marlene E.