Dietary Iron Deficiency and Oversupplementation Increase Intestinal Permeability, Ion Transport, and Inflammation in Pigs.
BACKGROUND Understanding the influence of dietary iron deficiency and dietary iron oversupplementation on intestinal health is important for both animal production and human health. OBJECTIVE The aim of this study was to determine whether dietary iron concentration influences intestinal physiology, morphology, and inflammation in the porcine duodenum. METHODS Twenty four male pigs (21 d old) were fed diets containing either 20 mg Fe/kg [low dietary iron (L Fe) 120 mg Fe/kg [adequate dietary iron (A Fe) control] or 520 mg Fe/kg [high dietary iron (H Fe) by FeSO4 supplement (dry matter basis) After 32 36 d, the duodenum was harvested from pigs and mounted in Ussing chambers for the measurement of transepithelial electrical resistance (TER) short circuit current, and (3)H mannitol permeability. Intestinal morphology and inflammation were assessed by histologic examination, and proinflammatory gene expression was assessed by real time polymerase chain reaction. RESULTS Compared with A Fe fed pigs, pigs fed L Fe diets exhibited reduced TER (by 30% P 0.05) Compared with that of A Fe fed controls, the paracellular flux of (3)H mannitol across the duodenal mucosa was higher (P 0.05) in L Fe fed >100% and H Fe fed ~4 fold) pigs; the L Fe fed and H Fe fed groups did not differ significantly from one another. Compared with the L Fe fed pigs, the A Fe fed and H Fe fed pigs had malondialdehyde concentrations 1.4 and 2.5 fold higher in the duodenum and 4.4 and 6.6 fold higher in the liver, respectively (P 0.05) Neutrophil counts were higher in both the L Fe fed (by 3 fold) and H Fe fed (by 3.3 fold) groups than in the A Fe fed group; the L Fe fed and H Fe fed groups did not significantly differ from one another. Duodenal mucosal tumor necrosis factor a (TNFA) interleukin (IL) 1b, and IL6 relative gene expression was upregulated by 36% 28% and 45% respectively, in H Fe pigs (P 0.05) but not in L Fe pigs, compared with A Fe pigs. CONCLUSION These data suggest that adequate but not oversupplementation of dietary iron in pigs is required to maintain intestinal barrier health and function.
The Journal of nutrition