Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2009
Publication Date: 6/29/2009
Citation: Patterson, J., Rutzke, M.A., Fubini, S.L., Glahn, R.P., Welch, R.M., Lei, X., Miller, D.D. 2009. Dietary inulin supplementation does not promote colonic iron absorption in a porcine model. Journal of Agricultural and Food Chemistry. 57(12):5250-5256. Interpretive Summary: Prebiotics, such as inulin, are non-digestible carbohydrates that pass through the stomach and small intestine of humans largely undigested and pass into the large intestine where they promote a favorable environment for the growth of beneficial bacterial populations such as bifidobacteria and lactobacilli. Prebiotics are currently being advocated as a therapeutic/preventative measure for many intestinal and extra intestinal diseases and disorders, and may also have applications in mineral nutrition. While several studies have demonstrated an enhancing effect of inulin and prebiotics on calcium absorption, their impact on iron absorption remains to be fully elucidated. We hypothesized that inulin enhances iron bioavailability by increasing iron absorption in the large intestine. We used a porcine model to determine the contribution of the small and large intestine to iron absorption from diets with or without supplemental inulin. Our results suggest that the colon does not make a significant contribution to total iron absorption in iron deficient pigs. This information is useful for further investigations on prebiotics by other researchers.
Technical Abstract: 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 54 Fe in the morning feed followed by cannula infusion of 0.5 mg 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 measurement and stable isotope detection. 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%, while colonic iron absorption was 0.4 +/- 0.1 and 1.0 +/- 0.2%, in inulin-fed and control pigs respectively (P > 0.05; Mean +/- SEM). These results suggest that the colon does not make a significant contribution to total iron absorption in iron deficient pigs.