Can SIBO, dysbiosis, and increased intestinal permeability contribute to iron deficiency?

Mucosal inflammation and barrier dysfunction

• SIBO and intestinal dysbiosis drive local and systemic inflammatory pathways, which are exacerbated by increased intestinal permeability.
• Increased permeability allows luminal antigens and microbial components to translocate across the epithelial barrier, triggering immune activation and chronic mucosal inflammation characterized by elevated cytokines such as IL-6.

Altered host transporter function

• Chronic inflammation and elevated IL-6 levels promote the hepatic transcription and secretion of hepcidin, a key iron-regulatory hormone.
• Hepcidin binds to and degrades the basolateral iron exporter ferroportin, while also triggering the proteasomal degradation of the apical importer divalent metal transporter 1 (DMT1).
• Concurrently, dysbiosis-related metabolites suppress HIF-2α, further down-regulating DMT1 and impairing both the apical uptake and basolateral export of dietary iron into systemic circulation.

Microbial competition for nutrients

• The massive expansion of bacterial biomass in SIBO results in direct competition between the host and overgrown microflora for luminal nutrients.
• Siderophore-producing bacterial taxa, such as Enterobacteriaceae, expand during dysbiosis and actively secrete high-affinity iron-chelating siderophores that bind and sequester free luminal iron into microbial biomass, rendering it unavailable for host absorption.

Bottom line

• SIBO, dysbiosis, and increased intestinal permeability impair host iron absorption through a dual mechanism of direct microbial sequestration via bacterial siderophores and inflammatory host-mediated suppression of key iron transporters (DMT1 and ferroportin), directly driving systemic iron deficiency.