Effect of Types of Levan with or without Phytic Acid on Intestinal Environment and Mineral Absorption in Rats

Effects of high-molecular weight levan (HL, 6,000 kDa) and low-molecular weight levan (LL, 700 kDa), alone and in combination with phytic acid (PA), on the gastrointestinal physiology of rats were examined. Levan, ${\beta}$-2,6-linked fructose polymer, is found in plants and by-products of microorganism with widely differing sizes. Male SD rats were randomly divided into five groups and fed control diet, diet containing 10% HL, 10% LL, 10% HL+ 1% PA or 10% LL+ 1% PA for 3 weeks. Intake of levans regardless of molecular weight significantly increased cecum content weight by four-to five fold and cecal wall weight by two fold, which were slightly decreased by PA intake. Higher acidification of cecal pH and enhancement of cecal total short-chain fatty acid production in LL group increased divalent cation absorption compared to HL group. Addition of PA to levan diet reduced intestinal fermentation of levans in rats. These results demonstrate LL has higher prebiotic properties than HL.