We investigated the effects of continuous and massive intake of chitosan with sodium ascorbate (AsN) on the mineral and the fat-soluble vitamin status in male Sprague-Dawley rats fed on a high-fat diet. The apparent fat digestibility in the chitosan-receiving group was significantly lower than that in the cellulose- or glucosamine-receiving group. Chitosan feeding for 2 weeks caused a decrease in mineral absorption and bone mineral content, and it was necessary to administer twice the amount of Ca in the AIN-76 formula, which was supplemented with AsN, to prevent such a decrease in the bone mineral content. Moreover, the ingestion of chitosan along with AsN led to a marked and rapid decrease in the serum vitamin E level, while such a loss in vitamin E was not observed for rats given glucosamine monomer instead of chitosan.