Prebiotic effects and intestinal fermentation of cereal arabinoxylans and arabinoxylan oligosaccharides in rats depend strongly on their structural properties and joint presence

Scope: Cereal arabinoxylan (AX) is one of the main dietary fibers in a balanced human diet. To gain insight into the importance of structural features of AX for their prebiotic potential and intestinal fermentation properties, a rat trial was performed. Methods and results: A water unextractable AX-rich preparation ( WU-AX, 40% purity), water extractable AX ( WE-AX, 81% purity), AX oligosaccharides ( AXOS, 79% purity) and combinations thereof were included in a standardized diet at a 5% AX level. WU-AX was only partially fermented in the ceco-colon and increased the level of butyrate and of butyrate producing Roseburia/E. rectale spp. Extensive fermentation of WE-AX and/or AXOS reduced the pH, suppressed relevant markers of the proteolytic breakdown and induced a selective bifidogenic response. Compared with WE-AX, AXOS showed a slightly less pronounced effect in the colon as its fermentation was virtually complete in the cecum. Combining WU-AX and AXOS caused a striking synergistic increase in cecal butyrate levels. WU-AX, WE-AX and AXOS together combined a selective bifidogenic effect in the colon with elevated butyrate levels, a reduced pH and suppressed proteolytic metabolites. Conclusion: The prebiotic potential and fermentation characteristics of cereal AX depend strongly on their structural properties and joint presence.