Quantifying the amount and bioavailability of iron in eggs

The quantity and bioavailability of iron (Fe) in eggs have been subject to ongoing debate. This study aimed to accurately quantify and characterise Fe speciation (including haem and non-haem Fe) in egg yolk, albumen and whole eggs, in both raw and cooked eggs.  

Eggs were obtained from four different hen housing systems: free-range, cage, barn and organic. Total Fe was measured using Microwave Plasma Atomic Emission Spectrometry, and X-ray absorption near-edge structure spectroscopy was used to quantify the relative proportions of different chemical forms of Fe (Fe speciation). These analyses were conducted on raw albumen, yolk, and whole egg samples (combined yolk and albumen) from eggs produced across all housing systems, as well as on baked and boiled albumen, yolk, and whole egg samples from free-range eggs.  

Results showed that eggs contain, on average, 0.77 mg of iron per 60g egg, but does not represent a nutrionally significant source of haem iron, with production system playing no part in affecting the iron concentration of eggs.