The intake of dietary fiber from grape seeds modifies the antioxidant status in rat cecum

The aim of this study was to measure the antioxidant activity and polyphenolic compounds in cecum and feces of rats fed with a grape seed concentrate. The grape concentrate was rich in indigestible compounds (dietary fiber, polyphenols and other associated compounds) which presented significant antioxidant activity. Polyphenols extracted by aqueous–organic solvents (extractable polyphenols, EPs) and non‐extractable polyphenols (NEPs) exhibited high antioxidant capacity as measured by the ABTS method. High correlations were found between antioxidant capacity values and EP ( r 2 = 0.9608) and NEP content ( r 2 = 0.9179). EPs and NEPs exhibited considerable antioxidant activity within the large intestine. Significant antioxidant activity was also found in feces derived from excreted EPs and NEPs. The grape fiber concentrate enhanced the antioxidant status in the large intestine. The antioxidant activity in the intestinal content should be considered when assessing the effects of dietary components on bowel diseases.