To study the effect of dietary sugars and starches on parameters linked to colon carcinogenesis, female Sprague-Dawley rats were fed for one month five different diets containing sucrose, glucose, fructose, cornstarch, or Hylon 7, a starch with a high amylose content. After this period, colon proliferation, assessed by [3H] thymidine incorporation in vitro, was higher (p < 0.05) in rats fed sucrose than in rats fed glucose, fructose, or cornstarch [labeling index was 7.17 +/- 0.75, 5.03 +/- 0.07, 4.55 +/- 0.72, 4.00 +/- 0.70, and 5.89 +/- 1.05 (SE) in sucrose, glucose, fructose, cornstarch, and Hylon 7 diets, respectively]. Cecal pH was lower in rats fed cornstarch and Hylon 7 than in rats fed sucrose, glucose, or fructose. Content of short-chain fatty acids (SCFAs) in the cecum was higher in rats fed Hylon 7 than in those fed glucose and fructose. In conclusion, glucose and fructose, compared with sucrose, decrease mucosal proliferation and may be considered protective factors in colon carcinogenesis, although they do not affect SCFA production and cecal pH. On the contrary, Hylon 7 does not change mucosal proliferation but increases SCFAs and lowers cecal pH, two conditions associated with a lower risk of colon cancer.