Dietary iron and heme, likely through their effect on gut commensal bacteria and colonic barrier function, have been shown to modulate colonic inflammation in animal models of colitis.
Nonetheless, the link between dietary total and heme iron and risk of Crohn's disease and ulcerative colitis has not been previously explored.
Dr Hamed Khalili and colleagues conducted a prospective cohort study of 165,331 U.S. women enrolled in the Nurses' Health Study and Nurses' Health Study II.
Dietary information was collected using a validated food frequency questionnaire at baseline (1984) and updated every 2 to 4 years.
Self-reported Crohn's disease and ulcerative colitis diagnoses were confirmed through medical records review.
|There was no association between dietary heme iron and risk of Crohn's disease|
|Inflammatory Bowel Diseases|
The research team performed a case–control study, and evaluated the interaction between single-nucleotide polymorphisms associated with genome-wide susceptibility to Crohn's disease and UC and dietary total and heme iron intake on risk of Crohn's disease and ulcerative colitis using logistic regression modeling.
Through 2011, over 3,038,049 person-years of follow-up, the team documented 261 incident cases of Crohn's disease, and 321 incident cases of ulcerative colitis.
The team observed that dietary heme iron was nonsignificantly associated with increased risk of ulcerative colitis.
This association seemed to be modified by the ulcerative colitis susceptibility locus, rs1801274, a coding variant in the FcγRIIA gene.
In contrast, there was no association between dietary heme iron and risk of Crohn's disease.
The researchers did not observe an association between total dietary intake of iron and risk of Crohn's disease or ulcerative colitis.
Dr Khalili's team concludes, "In 2 large prospective cohort studies, dietary total and heme iron were not associated with risk of Crohn's disease or ulcerative colitis."
"Our suggestive finding that the association between dietary heme iron intake and risk of ulcerative colitis may be modified by a coding variant in FcγRIIA gene warrants additional investigation."