C57BL/6J-Min/+ mice, which are heterozygous for a non-sense mutation in the Apc gene, provide a model for both familial adenomatous polyposis and sporadic colon cancers. In our study, gut tumors and small intestine lymphoid nodules were counted in Min mice fed fiber-enriched diets for 6 weeks. Neither starch-free wheat bran nor resistant starch modified the number of tumors. However, short-chain fructo-oligosaccharides dramatically reduced the incidence of colon tumors and concomitantly developed gut-associated lymphoid tissue. Our experiment shows that short-chain fructo-oligosaccharides counteract advanced stages of colon carcinogenesis, possibly via stimulation of antitumoral immunity by modulation of the colonic ecosystem.