The effect of uncooked potato starch in the diet on cecal fermentation and absorption of volatile fatty acids and on changes in the digestive supply of nutrients were investigated. Dietary potato starch (25%) markedly increased cecal size and the cecal pool of volatile fatty acids. These were maximal in the postabsorptive state, whereas the most acidic cecal pH readings were observed during the late absorptive period. Compared to the basal diet, feeding potato starch did not change arterial concentrations of glucose, lactate or alanine. Nevertheless, blood acetate was increased, whereas plasma triglycerides and cholesterol were reduced. The digestive balance of nutrients was determined by measurements of portal blood flow and arteriovenous differences across the digestive tract: the digestive supply of glucose was maximal during the absorptive period, but was lower in rats fed the potato starch diet. The absorption of volatile fatty acids was strongly increased by feeding potato starch and was maximal in the postabsorptive state, whereas glucose absorption was finished. The volatile fatty acids the constituted the main source of energetic fuels coming from the digestive tract. These results indicate that the effect of potato starch on digestion and metabolism is similar to that of dietary fibers, and that the regular supply of large amounts of volatile fatty acids, particularly during the postabsorptive period, could bring about substantial changes in liver metabolism.