Iron deficiency is a common complication in patients with IBD and oral iron therapy is suggested to exacerbate IBD symptoms.
Professor Dirk Haller and colleagues from Germany performed an open-labelled clinical trial to compare the effects of per oral versus intravenous (IV) iron replacement therapy.
The researchers evaluated patients with Crohn's disease, ulcerative colitis, and control subjects with iron deficiency.
After randomization, participants received iron sulfate per oral or iron sucrose IV over 3 months.
Clinical parameters, fecal bacterial communities and metabolomes were assessed before and after intervention.
The researchers found that both participants received iron sulfate, and IV treatments ameliorated iron deficiency, but higher ferritin levels were observed with IV.
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Changes in disease activity were independent of iron treatment types.
The team characterized fecal samples in IBD by marked interindividual differences, lower phylotype richness and proportions of Clostridiales.
Metabolite analysis also showed separation of both ulcerative colitis and Crohn's disease from control anemic participants.
The researchers observed major shifts in bacterial diversity in approximately half of all participants after iron replacement therapy, but patients with Crohn's disease were most susceptible.
Despite individual-specific changes in phylotypes due to iron replacement therapy, participants received iron sulfate treatment was associated with decreased abundances of operational taxonomic units assigned to the species Faecalibacterium prausnitzii, Ruminococcus bromii, Dorea sp. and Collinsella aerofaciens.
The research team noted that clear IV-specific and participants received iron sulfate-specific fingerprints were evident at the level of metabolomes, with changes affecting cholesterol-derived host substrates.
Professor Haller's team concludes, "Shifts in gut bacterial diversity and composition associated with iron treatment are pronounced in IBD participants."
"Despite similar clinical outcome, oral administration differentially affects bacterial phylotypes and faecal metabolites compared with IV therapy."