British Journal of Nutrition

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Dietary inulin affects the expression of intestinal enterocyte iron transporters, receptors and storage protein and alters the microbiota in the pig intestine

E. Takoa1 c1, R. P. Glahna2, R. M. Welcha2, X. Leia3, K. Yasudaa2 and D. D. Millera1

a1 Department of Food Science,

a2 US Plant, Soil, and Nutrition Laboratory and

a3 Department of Animal Science, Cornell University, Ithaca, NY 14853, USA

Abstract

Inulin, a linear β fructan, is present in a variety of plants including chicory root and wheat. It exhibits prebiotic properties and has been shown to enhance mineral absorption and increase beneficial bacteria in the colon. The aim of the present study was to assess the effect of dietary inulin on the gene expression of selected intestinal Fe transporters and binding proteins. Anaemic piglets at age 5 weeks were allocated to a standard maize–soya diet (control) or the same diet supplemented with inulin at a level of 4 %. After 6 weeks, the animals were killed and caecum contents and sections of the duodenum and colon were removed. Segments of the genes encoding for the pig divalent metal transporter 1 (DMT1) and duodenal cytochrome-b reductase (Dcytb) were isolated and sequenced. Semi-quantitative RT-PCR analyses were performed to evaluate the expression of DMT1, Dcytb, ferroportin, ferritin, transferrin receptor (TfR) and mucin genes. DMT1, Dcytb, ferroportin, ferritin and TfR mRNA levels in duodenal samples were significantly higher in the inulin group (P ≤ 0·05) compared with the control. In colon, DMT1, TfR and ferritin mRNA levels significantly increased in the inulin group. Additionally, the caecal content microflora was examined using 16S rDNA targeted probes from bacterial DNA. The Lactobacillus and Bifidobacterium populations were significantly increased in the inulin group (P ≤ 0·05) compared with the control group. These results indicate that dietary inulin might trigger an up regulation of genes encoding for Fe transporters in the enterocyte. The specific mechanism for this effect remains to be elucidated.

(Received March 14 2007)

(Revised July 06 2007)

(Accepted July 16 2007)

Correspondence:

c1 Corresponding author: Dr Elad Tako, fax +1 607 254 4868, email et79@cornell.edu

Footnotes

Abbreviations: Dcytb, duodenal cytochrome b reductase; DMT1, divalent metal transporter 1; FOS, fructo-oligosaccharide; IRE, Fe-responsive element; IRP, Fe-regulatory protein; TfR, transferrin receptor

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