|LEI, XIN GEN|
Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2006
Publication Date: 11/1/2006
Citation: Yasuda, K., Roneker, K.R., Miller, D.D., Welch, R.M., Lei, X. 2006. Supplemental dietary inulin affects bioavailability of iron present in corn and soybean meal to young pigs. Journal of Nutrition. 136:3033-3038.
Interpretive Summary: Over 2 billion people are afflicted with iron deficiency globally especially the poor in developing nations. This is primarily the result of poor bioavailable levels of iron in staple cereal grains and legume seeds because of these foods contain high levels of substances (i.e., antinutrients such as phytic acid and polyphenolics) that significantly reduce the amount of iron (i.e., bioavailable iron) that is absorbable from a diet based on these staples. Ways need to be found to improve the bioavailability of iron from these staples to reduce iron deficiency rates worldwide. Inulin is a non-digestible carbohydrate that enhances the proliferation of beneficial bacteria (e.g., bifidobacteria) in the hind gut (i.e., colon). Enhancing the activity of these bacteria has been reported to improved calcium bioavailability in human trials. We tested the ability of inulin to enhance iron bioavailability in a corn-soybean diet using a pig model. Our results show that inulin does promote iron bioavailability to pigs suggesting that increasing inulin in diets of people dependent on staple plant foods high in antinutrients may reduce iron deficiency in populations dependent in these staple plant foods. Human trials are needed to confirm these results before advocating increasing inulin in major staple cereal grains and pulse seeds.
Technical Abstract: Iron deficiency represents one of the most common global nutritional disorders in humans. Our objective was to determine whether and how supplemental inulin improved bioavailability of iron intrinsically present in a corn-soybean meal based diet to young pigs for hemoglobin synthesis. In Experiment 1, 24 weanling pigs (n = 8) were fed a corn-soybean meal based diet (BD, without inorganic iron addition) or the BD + 2% or 4% inulin (Synergy 1: a mixture of oligofructose and long chain inulin HP, Orafti, Tienen, Belgium) for 5 wk. Final blood hemoglobin concentrations and the overall hemoglobin repletion efficiency of pigs were positively (P < 0.01) correlated with dietary inulin concentrations. Compared with pigs fed the BD, those fed 4% inulin demonstrated a 28% improvement (P < 0.01) in hemoglobin repletion efficiency and 15% (P < 0.01) improvement in the final blood hemoglobin concentration. In Experiment 2, 12 weanling pigs (n = 6) were fed the BD or the BD + 4% inulin for 6 wk. Pigs fed 4% inulin had higher (P < 0.05) soluble Fe concentrations in the digesta of the proximal, mid, and distal colon, and lower (P < 0.05) sulfide concentrations in the digesta of the distal colon. Supplemental inulin had virtually no effect on pH or phytase activity of digesta in any segments between the stomach and the distal colon. In conclusion, supplementing 4% inulin improved utilization of intrinsic iron in the corn-soybean meal diet by young pigs, and this benefit was associated with soluble Fe and sulfide concentrations but not pH or phytase activity in the digesta.