The researchers from the Federal University of São Paulo’s Department of Paediatrics looked at the impact of inulin and oligofructose on factors that regulated the release and storage of iron in anaemic rats during their growth phase.
Male rats from the age of 21 days were fed a diet without iron for two weeks to induce iron-deficient anaemia, after which they were fed a control diet, a diet with 10% inulin or a diet with 10% oligofructose without iron supplementation.
The ‘high performance’ inulin used was made up of 97 g dietary fibre per 100 g, while the oligofructose was made up of 5 g carbohydrate and 92 g dietary fibre.
After two weeks on these diets the rats were euthanised and their duodenum (the first and shortest segment of the small intestine), caecum (a pouch at the beginning of the large intestine), colon and liver examined.
The results, published in the British Journal of Nutrition, suggested inulin increased the expression of the divalent metal transporter protein in the caecum by 162% and the expression of duodenal cytochrome b reductase in the colon by 136% - both factors that impacted the absorption of iron.
Effects & mechanisms
Meanwhile, the oligofructose group did not see differences in these proteins compared with the control group but urinary concentrations of the iron-regulator hepcidin were decreased as was the expression of certain influencing proteins in the duodenum (the ferroportin protein) and the caecum (TNF-a, interleukin-6 and interleukin-10).
“Therefore, in the present study, it is clear that high performance inulin and oligofructose exerted promotive effects via different mechanisms,” the researchers wrote.
“Most probably, the benefit of inulin and oligofructose in iron-deficiency anaemia can be exercised beyond the stage of intestinal absorption of iron, for example at the stage of transfer, storage and recycling of iron. It remains to be unknown whether inulin and oligofructose could modulate the expression levels of these genes in iron metabolism.”
The researchers said hepcidin and the immune system’s IL (interleukin) signalling pathways had been investigated in relation to inflammatory anaemia, but had been neglected in terms of iron-deficient anaemia.
Inflammatory anaemia (also known as anemia of chronic disease ACD) refers to the body’s natural protective response to life-threatening illnesses whereby it limits the amount of iron available to protect the iron from the threat of harmful substances. It does with with the protein ferritin, which stores and releases iron.
They said further studies were needed to clarify the influence of these prebiotics on IL in iron-deficient anaemia, considering the IL may aggravate anaemia through this immune response.
Source: British Journal of Nutrition
Published online ahead of print, doi:10.1017/S0007114514004334
“Effects of prebiotic supplementation on the expression of proteins regulating iron absorption in anaemic growing rats”
Authors: R. Marcianoa, A. Boveto Santamarinaa, A. Alves de Santanaa, M. de Lima Correia Silvaa, O. Maria Silvério Amancioa, C. Maria da Penha Oller do Nascimentoa, L. Missae Oyamaa and M. Batista de Moraisa