Excess Iron Also Disrupts Your Gut Bacteria
Beyond direct chemical damage, excess colonic iron may also disrupt the gut microbiome — an effect documented mainly in iron fortification studies in children, and whose contribution to constipation from iron supplements in adults is plausible but not yet directly established.
This is relevant to gut function because beneficial gut bacteria produce short-chain fatty acids (SCFAs) that help regulate colonic motility and water balance. When protective species decline and potentially pathogenic bacteria increase, reduced SCFA production could plausibly affect colonic motility — though direct evidence linking iron-induced dysbiosis to constipation in adults remains limited.