Prebiotic GOS and Lactoferrin for Beneficial Gut Microbiota With Iron Supplements

Iron deficiency, the principal cause of anemia globally, affects more than two billion individuals, predominantly infants, children and women of childbearing age. Iron deficiency impairs cognitive and behavioral development in childhood, compromises immune responsiveness, decreases physical performance, and when severe, increases mortality among infants, children and pregnant women. Effective prevention and treatment of iron deficiency uses iron supplements or fortificants to increase oral iron intake. Generally, only a small fraction of the added iron is absorbed in the upper small intestine, with 80% or more passing into the colon. Because iron is an essential micronutrient for growth, proliferation, and persistence for most intestinal microbes, the increase in iron availability has profound effects on the composition and metabolism of intestinal microbiota. In particular, iron is a prime determinant of colonization and virulence for most enteric gram-negative bacteria, includingmSalmonella, Shigella and pathogenic Escherichia coli. Commensal intestinal microorganisms, principally of the genera Bifidobacterium and Lactobacillus, require little or no iron, provide a barrier effect and can inhibit pathogen growth by a variety of methods, including sequestration of iron, competition for nutrients and for intestinal epithelial sites stabilization of intestinal barrier function, and production of antibacterial peptides and organic acids that lower the pH. Increases in unabsorbed iron can promote the growth of virulent enteropathogens that overwhelm barrier strains and disrupt the gut microbiota.

We hypothesize that the combination of prebiotic GOS with bovine lactoferrin (bLF), adding iron sequestration, antimicrobial and immunomodulatory activities, will provide virtually complete protection against the adverse effects of added iron on the intestinal microbiota. Our research has two specific aims:

1. to conduct a randomized, controlled double-blind 9-month clinical trial in 6-month old Kenyan infants comparing the effects on gut microbiome composition among groups receiving in-home fortification for 6 months with micronutrient powders containing 5 mg iron (as sodium iron EDTA [2.5 mg] and ferrous fumarate [2.5 mg]) and (i) galacto-oligosaccharides (GOS; 7.5 g), (ii) bovine lactoferrin (bLF, 1.0 g), (iii) GOS (7.5 g) and bLF (1.0 g), and (iv) no GOS or bLF. Each infant will then be followed for an additional 3 months to determine the longer-term effects of the treatments.
2. to examine mechanisms of iron, prebiotic GOS and iron-sequestering bLF on microbiota composition, enteropathogen development, microbiota functions and metabolic activity, and inflammatory potential in vitro with treatments paralleling those in Specific Aim 1, using immobilized fecal microbiota from Kenyan infants to inoculate our established long-term continuous polyfermenter intestinal model (PolyFermS) to mimic Kenyan infant colon conditions, together with cellular studies.

Combining in vivo clinical and in vitro approaches will help guide formulation of safer iron supplements and fortificants and improve our understanding of the mechanisms whereby prebiotic GOS and iron-sequestering bLF support commensal microbiota to prevent iron-induced overgrowth by opportunistic enteropathogens.