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Research Paper
Suppression of Azoxymethane-Induced Colon Cancer Development in Rats by Dietary Resistant Starch
Richard K. Le Leu, Ian L Brown, Ying Hu, Adrian Esterman and Graeme P. Young
volume 6 | issue 10
October 2007Pages: 1621 - 1626
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Resistant starch is a complex carbohydrate that reaches the colon where it can be fermented by the colonic microflora resulting in production of short chain fatty acids (SCFA), in particular butyrate. RS effects on colorectal tumourigenesis are contrasting and protection remains controversial. Butyrate has an important role as the preferred metabolic fuel and regulator of colonocyte proliferation, differentiation and apoptosis and may play a role in cancer prevention. Thus variation in butyrate production from different substrates might explain the variation in effect of RS. This study evaluated the hypothesis that feeding dietary resistant starch (as high amylose maize starch) would protect against azoxymethane (AOM)-colon carcinogenesis and favourably influence the colonic luminal environment. Male Sprague-Dawley rats (n = 90 were provided one of three diets: Control (without added dietary fibre or RS), 10% HAS (contained 100 g/kg raw high amylose maize starch) or 20% HAS (contained 200 g/kg high amylose maize starch). Rats were fed their experimental diets for 4 weeks after which they were injected with AOM (15 mg/kg) during the fifth and six week. Colons were resected (25 weeks post second injection) for evaluation of tumour formation, apoptosis, proliferating cell nuclear antigen (PCNA) labelling index and short chain fatty acid levels. Feeding resistant starch significantly reduced the incidence (P<0.01) and multiplicity (P<0.05) of adenocarcinomas in the colon compared to the Control diet. Both doses of HAS resulted in similar protection against colon tumourigenesis. Feeding RS significantly increased total SCFA concentrations, including butyrate in the distal colon. Apoptosis (P<0.01) was also enhanced while PCNA labelling index was reduced (P<0.01) in the distal colon with resistant starch feeding. The protective effect of consumption of RS as dietary high-amylose cornstarch against colon cancer development appears to be related to active fermentation in the colon, particularly through production of butyrate.
Authors
Richard K. Le Leu
Department of Medicine, Flinders University of South Australia; Bedford Park, Australia
Ian L Brown
Department of Medicine, Flinders University of South Australia, Bedford Park, Australia
Ying Hu
Department of Medicine, Flinders University of South Australia, Bedford Park, Australia
Adrian Esterman
School of Nursing and Midwifery, University of South Australia
Graeme P. Young
Department of Medicine, Flinders University of South Australia, Bedford Park, Australia
We now provide open access to journal articles published online for one year or more. This article may be downloaded at the following link:
Download PDFIf the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.