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Effects of Iron Fortification on the Gut Microflora, Gut Inflammation, and Diarrhoea in Infants and Children

Posted:  Monday, September 05, 2016

Fortification of Foods with Iron: Consequences on the Gut Microflora, Gut Inflammation, and Diarrhoea in Infants and Children

Iron deficiency anaemia (IDA) is one of the most common causes of disease, disability and death in young children. A review published in the journal Nutrients discussed the effects of iron fortification on the gut microflora, gut inflammation, and diarrhoea in infants and children.

According to World Health Organization, IDA in children aged 6–23 months can be reduced with in-home iron fortification of foods using micronutrient powders (MNPs). However, the safety of high dose iron MNPs is unclear. It has been reported that increasing the iron intake in infants and children through the use of supplements or MNPs may increase the incidence of diarrhoea. Furthermore, a study in preschool children has reported that provision of iron supplements at 12.5 Fe mg/day, the same dose as in the “sprinkles” formulation of MNPs, was associated with increased risk of serious adverse events, hospitalisations, and mortality.

Iron is important for virulence and colonisation for most enteric gram-negative bacteria (Salmonella, Shigella or pathogenic Escherichia coli). Commensal gut bacteria (Lactobacillus and Bifidobacterium) offer a ‘barrier effect’ against colonisation by pathogens. An increase in unabsorbed iron through fortification could alter the colonic microflora and support growth of pathogenic strains over the healthy ‘barrier’ strains. It has been demonstrated that providing iron-fortified MNPs to infants leads to an adverse shift in gut microbiota, increases gut inflammation, and abundances of enteropathogens. Furthermore, a significant increase in enterobacteria (Escherichia/Shigella), the enterobacteria/bifidobacteria ratio, and Clostridium spp. was observed among infants who received iron-containing MNPs compared with those who received MNPs without iron.

The review highlighted that while iron-containing MNPs reduce the risk of IDA, they could also increase gastrointestinal morbidity in infants. Additional research is required to understand the effects of iron on gut microflora of infants and children and improve the safety of MNPs.

News source - Paganini D, Uyoga MA, Zimmermann MB. Iron Fortification of Foods for Infants and Children in Low-Income Countries: Effects on the Gut Microbiome, Gut Inflammation, and Diarrhea. Nutrients. 2016; 8(8). pii: E494.