Iron bioavailability and pro- and prebiotics

Abstract: Iron deficiency is one of the most frequent micronutrient deficiencies around the world. Low iron bioavailability simultaneously with a high iron requirement is a high risk factor for developing iron deficiency. Probiotics are microorganisms that confer a health benefit on the host. Prebiotics are oligosaccharides which provide a health benefit on the host due to a positive modulation of the microflora in the gut. The aim of this paper is to evaluate if there is a connection between pro-and/or prebiotics and iron bioavailability. A literature review of studies published within the last ten years was done together with information from the organizations WHO, FAO and EFSA.In the literature search, only four, published, human studies investigating the correlation between probiotics and iron bioavailability was found. Since the properties of probiotics always are strain specific studies done on different strains cannot be summarized in one conclusion. Lactobacillus plantarum 299v is a probiotic strain proposed to give enhanced iron absorption. An improvement of iron absorption was observed when the strain was added to a phytate rich meal. Trials with longer intervention periods are needed to assess the strain’s impact on iron absorption. Addition of Lactobacillus acidophilus to an iron fortified beverage did not improve iron status among children. Contrary, a decreased risk of developing iron deficiency anemia was observed when Bifidobacterium lactis HN019 and prebiotic oligosaccharides were added to an iron-fortified beverage. The positive outcome can be an act of the pro- or the prebiotic or a collaboration of both. The hypothesis that prebiotics can improve iron bioavailability, can unfortunately not be proven since there are not many human studies done to support the theory. Nevertheless there are four plausible biological mechanisms behind the hypothesis. The fermentation products, the short chain fatty acids, SCFA can release iron from complexes by a lowering of the pH, furthermore SCFA can enlarge the absorption area by stimulate the epithelial cells to proliferate. Prebiotics can give a reducing environment where iron can be reduced to the more soluble ferrous form. Additionally prebiotics can give an up regulation of the genes encoding for iron transporters and receptors. Studies performed on pigs indicate a positive outcome of prebiotic inulin on iron status. Additional human studies are required to support this result.Conclusion: The relationship between pro- and/or prebiotics and improved bioavailability of iron requires further human studies to be confirmed.