Micronutrient supplements with iron promote disruptive protozoan and fungal communities in the developing infant gut

Popovic, Ana; Bourdon, Celine; Wang, Pauline W.; Guttman, David S.; Soofi, Sajid; Bhutta, Zulfiqar A.; Bandsma, Robert H. J.; Parkinson, John; Pell, Lisa G.

Supplementation with micronutrients, including vitamins, iron and zinc, is a key strategy to alleviate child malnutrition. However, adverse events resulting in gastrointestinal disorders, largely associated with iron, has resulted in ongoing debate over their administration. To better understand their impact on gut microbiota, we analysed the bacterial, protozoal, fungal and helminth communities of stool samples collected from children that had previously been recruited to a cluster randomized controlled trial of micronutrient supplementation in Pakistan. We show that while bacterial diversity was reduced in supplemented children, vitamins and iron may promote colonization with distinct protozoa and mucormycetes, whereas the addition of zinc ameliorates this effect. In addition to supplements, residence in a rural versus urban setting is an important determinant of eukaryotic composition. We suggest that the risks and benefits of such interventions may be mediated in part through eukaryotic communities, in a manner dependent on setting.