Ulcerative Colitis Resource Center

Ulcerative Colitis Resource Center

February 19, 2016
1 min read

Oral, IV iron replacement impact gut microbiome, metabolome in patients with IBD

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Researchers have observed that the gut microbiota in patients with inflammatory bowel disease are distinctly altered by iron replacement therapy depending on the route of administration. They also found iron replacement therapy had more significant impacts in patients with Crohn’s disease vs. ulcerative colitis.

“Supplying iron either orally or intravenously has a very distinct effect on the intestinal microbiota,” Dirk Haller, PhD, from the Technical University of Munich, said in a press release. “The study shows how fragile the stability of the microbial community is, especially in patients with Crohn's disease.”

Haller and colleagues previously demonstrated in a mouse model that dietary iron alters dominant gut bacterial communities and exacerbates chronic ileal inflammation. To follow up on these findings, Haller and colleagues performed an open-label clinical trial of 31 patients with CD, 22 patients with UC and 19 controls, all of whom had iron deficiency. Participants were randomly assigned to receive per oral iron sulfate or IV iron sucrose over 12 weeks. Clinical data, fecal bacterial communities and metabolite profiles were analyzed before and after the iron intervention.

Both methods of iron administration improved iron deficiency, but higher ferritin levels were observed with IV administration. The route of iron administration did not affect disease activity based on changes in clinical disease activity indices and serum concentrations of C-reactive protein.

Fecal samples from both IBD groups demonstrated distinct interindividual differences in 16S rRNA profiles vs. control samples, which were more homogenous. IBD samples had lower taxa richness, especially in CD samples, which showed a reduced relative abundance of Clostridiales. IBD metabolome profiles were also distinct from controls.

Fecal iron content was higher after per oral (P = .014) but not after IV iron therapy. Oral therapy was associated with decreased abundance of operational taxonomic units of Collinsella aerofaciens, Faecalibacterium prausnitzii, Ruminococcus bromii and Dorea sp, and increased abundance of Bifidobacterium. Fecal metabolomes of IV and oral groups were also distinct.

“In conclusion, [iron replacement therapy] in patients with iron deficiency or anemia induced significant shifts in bacterial community structure and metabolite landscape in feces,” the researchers wrote. “Patients with CD seemed to be more prone to [iron replacement therapy]-induced shifts and, according to the load of free iron detected in the luminal environment, oral iron therapy affected the presence of specific molecular bacterial species.” – by Adam Leitenberger

Disclosure: The researchers report no relevant financial disclosures.