Annals of Family Medicine 3:131-137 (2005)
© 2005 Annals of Family Medicine, Inc.
doi: 10.1370/afm.283

Transferrin Saturation, Dietary Iron Intake, and Risk of Cancer
Arch G. Mainous, III, PhD1, James M. Gill, MD, MPH2 and Charles J.
Everett, PhD1
1 Department of Family Medicine, Medical University of South Carolina,
Charleston, SC
2 Department of Family and Community Medicine, Christiana Care Health
System, Wilmington, Del

CORRESPONDING AUTHOR: Arch G. Mainous III, PhD, Department of Family
Medicine, Medical University of South Carolina, 295 Calhoun St,
Charleston, SC 29425, mainouag@musc.edu

PURPOSE Transferrin saturation of more than 60% has been identified as
a cancer risk factor. It is unclear whether dietary iron intake
increases the risk of cancer among individuals with transferrin
saturation of less than 60%. The purpose of this study was to examine
the association of dietary iron intake and the risk of cancer among
adults with increased transferrin saturation.

METHODS Analysis of a cohort study, the National Health and Nutrition
Examination Survey I Epidemiologic Follow-Up Study, was performed. US
adults (aged 25 to 74 years at baseline) were followed up from baseline
in 1971-1974 to 1992 (N = 6,309).

RESULTS A total of 7.3% of the US population had a serum transferrin
saturation of more than 45% at baseline. Intake of dietary iron was
essentially uncorrelated with transferrin saturation (r = 0.04).
Compared with individuals who had normal serum transferrin saturation
and low dietary iron intake, individuals whose serum transferrin
saturation was more than 45% and who had high dietary iron intake also
had an increased adjusted relative risk of cancer (2.24; 95% confidence
interval [CI], 1.02-4.89). Increased risk was not found for individuals
with a transferrin saturation of more than 45% but a normal dietary
iron intake (hazard ratio, 1.02; 95% CI, 0.69-1.49). Transferrin
saturation levels could be set as low as 41%, and the individuals with
high transferrin saturation and high dietary iron intake would still
have an increased adjusted relative risk of cancer (hazard ratio, 2.00;
95% CI, 1.04-3.82).

CONCLUSIONS Among persons with increased transferrin saturation, a
daily intake of dietary iron more than 18 mg is associated with an
increased risk of cancer. Future research might focus on the benefits
of dietary changes in those individuals with increased serum
transferrin saturation.

Key Words: Cohort studies · transferrin saturation, diagnostic use
· iron, dietary · cocarcinogenesis · diet

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Copyright © 2005 by the Annals of Family Medicine.

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