Heme iron and non-heme iron, presented as ferrous sulfate, do not compete for absorption when ingested on an empty stomach.
The study involved twenty-six healthy, nonpregnant women who participated in two iron absorption research studies which utilised iron radioactive tracers. The process began by obtaining the dose-response curve for absorption of heme iron in different doses, arrayed as concentrated red blood cells. Subsequently, the absorption of these same doses were evaluated, but this time with the addition of non-heme iron in the form of ferrous sulfate, with a consistent heme/non-heme iron molar ratio of 1:1. Iron sources were administered on an empty stomach.
In analyzing the results, it was found that heme iron absorption was reduced simply by increasing total heme iron. Interestingly though, the addition of non-heme iron as ferrous sulfate exhibited no observable effect on the absorption of heme iron. This observation led to the conclusion that heme and non-heme iron, when presented as ferrous sulfate, do not compete for absorption. However, the underlying mechanism steering the absorption of these iron sources remains unclear.
