Modification of azoxymethane intestinal carcinogenesis in rats by feeding sucrose boluses, pasta, and glucose

We studied whether repeated boluses of sucrose or diets containing carbohydrates with a variable glycemic index (GI) affect intestinal carcinogenesis in rats. Male F344 rats were treated twice (1 wk apart) with 15 mg/kg sc azoxymethane (AOM) and then divided into four experimental dietary groups with different carbohydrate composition and administration schedules: the sucrose group was fed 44% (wt/wt) sucrose (GI = 65), the bolus group was fed sucrose as carbohydrate and 43 boluses of sucrose (10-15 g/kg) at various time intervals, the pasta group was fed pasta [77% (wt/wt) cooked pasta, GI = 55], and the glucose group was fed 44% (wt/wt) glucose (GI = 97). All nutrients, including carbohydrates, were provided in similar amount to the different groups. The experiment was terminated between Day 230 and Day 245 after AOM administration. At this time the pasta group had significantly higher cecal short-chain fatty acids than the other groups. Intestinal adenomas and cancers occurred with the same frequency in the bolus, sucrose, and glucose groups. On the contrary, we observed a significant decrease (p = 0.03) in the cumulative incidence of intestinal adenomas, but not adenocarcinomas, in the pasta group compared with the sucrose group (intestinal adenoma incidence in the pasta group was 31% compared with 63% in the sucrose group, 46% in the bolus group, and 37% in the glucose group). In conclusion, these results do not support the hypothesis that sucrose boluses or carbohydrates with a high GI stimulate colon carcinogenesis, but they indicate that foods such as pasta may exert a protective effect.