Dietary inulin supplementation does not promote colonic iron absorption in a porcine model

Prebiotics may enhance iron bioavailability by increasing iron absorption in the colon. Anemic pigs fitted with cecal cannulas were fed a low-iron diet with or without 4% inulin. Over 7 days, pigs were administered 1 mg of (54)Fe in the morning feed followed by cannula infusion of 0.5 mg of (58)Fe to measure total and colonic iron absorption, respectively. Whole blood was drawn prior to the initial dosing and 14 days thereafter for hemoglobin concentration and stable isotope ratio analyses. The prebiotic role of inulin was confirmed by increases in lactobacilli and bifidobacteria with reductions in clostridia using terminal restriction fragment length polymorphism (TRFLP). Total iron absorption was 23.2 +/- 2.7 and 20.7 +/- 3.5% (mean +/- SEM; p > 0.05), while colonic iron absorption was 0.4 +/- 0.1 and 1.0 +/- 0.2% (mean +/- SEM; p > 0.05) in inulin-fed and control pigs, respectively. These results show that the colon does not make a significant contribution to total iron absorption in iron-deficient pigs and that inulin does not affect iron absorption in the colon.