Oral iron exacerbates colitis and influences the intestinal microbiome

Area of Science:

• Gastroenterology
• Microbiology
• Nutrition Science

Background:

• Inflammatory bowel disease (IBD) is linked to anemia, often treated with oral iron, which can worsen inflammation.
• The gut microbiota is crucial in IBD pathogenesis, and iron supplementation may impact its diversity.
• Understanding the role of dietary iron in IBD and its interaction with the gut microbiome is essential.

Purpose of the Study:

• To investigate the impact of varying dietary iron concentrations on the clinical and histological severity of dextran sulfate sodium (DSS)-induced colitis.
• To assess how different dietary iron levels affect fecal microbial diversity in mice with colitis.

Main Methods:

• Adult female C57BL/6 mice were fed diets with 100, 200, or 400 ppm iron.
• Colitis was induced using DSS, and disease severity was evaluated clinically and histologically.
• Fecal microbial diversity was analyzed using 16S rRNA gene sequencing (V4 region).

Main Results:

• Both low (100 ppm) and high (400 ppm) dietary iron exacerbated DSS-induced colitis severity compared to standard (200 ppm) levels.
• Mice on 100 ppm iron lost more weight than those on 400 ppm iron during colitis.
• High dietary iron (400 ppm) altered gut microbiota composition in colitis, reducing Firmicutes and Bacteroidetes while increasing Proteobacteria.

Conclusions:

• Altering dietary iron intake, either increasing or decreasing from standard levels, exacerbates DSS-induced colitis in mice.
• Dietary iron concentration significantly influences gut bacterial diversity and composition in the context of colitis.
• These findings suggest a critical role for dietary iron modulation in managing IBD and its associated gut dysbiosis.