Serum iron concentration as a tool to measure relative iron absorption from elemental iron powders in man

Abstract

Objective: To present a new method for measuring the relative bioavailability (RBV) of commercial elemental iron powders by investigating induced changes of serum iron concentration (S‐Fe) in relation to ferrous sulphate (FeSO4). Earlier studies have shown that in a group of subjects there is good agreement between the increase in S‐Fe and the amount of iron absorbed from a simple iron salt as FeSO4. Methods: The study included two groups of male blood donors (n=2×16 subjects) who were served three meals with an interval of approximately nine weeks between each one. In one group the meal was fortified with reduced iron, ferrous sulphate or no iron at all. In the other group the meal was fortified with electrolytic iron, ferrous sulphate or no iron. The S‐Fe increase was followed for 6 h. Studying the non‐iron meals was necessary so that the basal diurnal variation in the S‐Fe during the six hours could be measured and subtracted. Results: The mean S‐Fe increase calculated as the area under the curve (AUC) from the reduced iron (RBV=0.43) and the electrolytic iron (RBV=0.73) differed significantly from the AUC following FeSO4 (p=0.002 and p=0.021, respectively). The difference between the reduced and the electrolytic iron was also statistically significant (p=0.036). Conclusion: Measuring increases in S‐Fe could be a reliable and simple method to determine the RBV in comparative studies of elemental iron powders in relation to FeSO4.