Comparison of native or reformulated chicory fructans, or non-purified chicory, on rat cecal fermentation and mineral metabolism

Chicory inulin has been identified as an effective prebiotic to promote active fermentation and lactobacilli proliferation in the large intestine, and to enhance calcium (Ca) digestive absorption and deposition in bones. The aim of this study was to compare, in a growing rat model, the effects on digestive fermentations and mineral metabolism of diets containing 7.5% inulin, using either a purified native inulin (_NATInulin) or a reformulated inulin (_REFInulin, based on a combination of short- and long chain fructans) or dehydrated chicory. All the inulin diets elicited a marked enlargement of the cecum and acidification of the cecal contents (P < 0.01) and these diets promoted succinic acid rich fermentation together with substantial amounts of short-chain fatty acids (SCFA), especially butyrate. After 1 month of adaptation, all the inulin diets strongly enhanced Ca absorption compared to controls (P < 0.01), but this effect was no more observed after 3 months of adaptation. Magnesium (Mg) absorption was stimulated by the inulin diets after 1 and 3 months experiment. Bone parameters were significantly affected by the chicory diet (enhanced distal bone mineral density and breaking load) whereas the purified inulin diets were less effective. In conclusion, with the present model, both _NATInulin and _REFInulin exerted similar effects as to (1) cecal fermentation and profile of end-products of bacterial metabolism, (2) stimulation of Ca and Mg digestive absorption and (3) overall effects on bone parameters. The particular effects of the chicory crude fractions on digestive fermentation and bone parameters suggest possible synergisms between inulin-type fructans and other nutrients.