Development of a Database for the Estimation of Heme Iron and Nonheme Iron Content of Animal-Based Foods

Abstract

BackgroundTotal iron (TI) intake and differentiation between heme iron (HI) and nonheme iron (NHI) are uncommon despite markedly different bioavailability. ObjectivesTo create a database compiling information from studies that directly assessed the HI content of animal products using the Hornsey method, and to explore differences in estimates of HI intake between the data compiled and the Monsen method. MethodsA literature search identified studies that chemically characterized the HI content of animal-based foods using the Hornsey method; HI, NHI, and TI contents (mg/100 g) were compiled. Information was grouped by animal type and cooking method, and mean (± SD) HI% was calculated. Using a 24-h dietary record, differences in HI and NHI intake using the compiled information and the Monsen approach were explored. ResultsActual HI% values ranged from 7% to 94%. Raw foods had the highest HI% [raw duck (94% ± 4%), raw blood curd (82% ± 4%), and raw beef (79% ± 9%)]. Boiled foods had the lowest HI% [boiled shrimp (11% ± 5%) and meatballs (15% ± 6%)]. Cooked foods with the highest HI% were beef (70% ± 10%) and lamb (70% ± 9%). In many instances, applying actual HI% from the complied database produced markedly different measures of the HI content of foods [cooked beef (Monsen: 1.3 mg/100 g); (Hornsey: 2.3 mg/100 g)]. Estimation of iron intake in a 24-h recall demonstrated that using animal-specific HI% results in different estimates of HI intake [Monsen: 1.2 mg HI (40%); Hornsey: 1.8 mg HI (59%)]. ConclusionsAnimal-based foods have variable HI%. A fixed HI:NHI ratio does not reflect this variation and could give rise to inaccurate estimates of HI content in food and HI intake. Consideration of this variation in HI% may improve our ability to link dietary intake with iron status and important health outcomes.