Relationship between dietary iron intake, corrected for diet reporting error, and serum ferritin in Danish women aged 35-65 years.

Abstract

Several studies have failed to demonstrate an association between Fe status and intake of dietary Fe. However, in the long term, it seems logical to presume that body Fe reserves are, fundamentally, dependent on the intake of bioavailable dietary Fe. This discrepancy may depend on several factors: (1) interindividual variation in biological availability of dietary Fe (differences in intestinal absorption), (2) interactions between dietary Fe and absorption enhancers and inhibitors, (3) variations in physiological (menstruation, childbirth) or unphysiological (blood donation) Fe losses, (4) the failure to adjust dietary intake data for Fe supplements, (5) uncertain food composition data (discrepancies between calculated and chemically measured Fe content in the diet), and (6) diet reporting error (reported intake of dietary Fe may deviate considerably from the true intake). The present study examined associations between dietary intake of Fe (assessed by diet history interview) and Fe status (assessed by ferritin status) among 167 Danish women aged 35-65 years, who were not blood donors, by taking into account diet reporting error (assessed from p-amino benzoic acid-validated urinary N), physiological blood losses (menstruation, childbirth, abortions), and Fe supplementation. Our results indicate that the lack of a general association between Fe status and dietary Fe intake may, in part, be caused by selective diet reporting error.