Carcinogenesis Advance Access originally published online on December 13, 2006
Carcinogenesis 2007 28(2):240-245; doi:10.1093/carcin/bgl245
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Effect of dietary resistant starch and protein on colonic fermentation and intestinal tumourigenesis in rats
Department of Medicine, Flinders University of South Australia Bedford Park, South Australia 5042, Australia
1 National Starch and Chemical Company Bridgewater, NJ 08807, USA
2 School of Nursing and Midwifery, University of South Australia South Australia 5000, Australia
3 Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University Shizuoka 422-8529, Japan
*To whom correspondence should be addressed. Tel: +61 88204 5170; Fax: +61 88204 3943; Email: richard.leleu{at}flinders.edu.au
Protein as well as starch is fermented in the colon, but the interaction between protein and starch fermentation and the impact on colonic oncogenesis is unknown. High-protein diets increase delivery of protein to the colon and might promote oncogenesis through generation of toxic products. We investigated the interaction of resistant starch (RS) with digestion-resistant potato protein (PP) on colonic fermentation events and their relationship to intestinal tumourigenesis. Male Sprague–Dawley rats were fed an AIN-76A-based diet for 4 weeks and intestinal neoplasms were induced by azoxymethane. Experimental diets included the following: no added RS or PP, 10% high amylose maize starch (source of RS) replacing digestible starch, 15% PP replacing casein and 10% high amylose maize starch + 15% PP. Rats were maintained on diets until killed at 30 weeks. Feeding RS significantly increased short-chain fatty acid (SCFA) levels (P < 0.001) in the caecum and colon. Importantly, butyrate concentration was significantly increased in the distal colon with RS (P < 0.001). Feeding PP increased protein fermentation products, but this effect was reduced by adding RS to the diet. Intestinal neoplasms and colorectal adenocarcinomas were reduced by feeding RS (P < 0.01) regardless of whether PP was fed, whereas PP alone increased the incidence and number of small intestinal neoplasms including the adenocarcinomas (P < 0.01). In conclusion, RS altered the colonic luminal environment by increasing the concentration of SCFAs including butyrate and lowering production of potentially toxic protein fermentation products. These effects of RS not only protected against intestinal tumourigenesis but also ameliorated the tumour-enhancing effects of feeding indigestible protein.
Abbreviations: BCFA, branched-chain fatty acid; CRC, colorectal cancer; HAS, high amylose cornstarch; PP, digestion-resistant potato protein; RS, resistant starch; SCFA, short-chain fatty acid
Received August 14, 2006; revised November 21, 2006; accepted November 27, 2006.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  S. Toden, A. R. Bird, D. L. Topping, and M. A. Conlon High red meat diets induce greater numbers of colonic DNA double-strand breaks than white meat in rats: attenuation by high-amylose maize starch Carcinogenesis, November 1, 2007; 28(11): 2355 - 2362. [Abstract] [Full Text] [PDF]
|
|