Losses of ingested iron temporarily retained in the gastrointestinal tract. A possible auxiliary mechanism for regulation of iron absorption.

Excretion of radioiron 1 month after oral intake was studied in 6 healthy men by means of whole-body-counting. In one of the subjects as much as 17.6% of the 59Fe retained 2 weeks after oral intake was subsequently excreted. The radioiron losses were not due to bleeding. There was a fairly close positive correlation between iron status of the subjects and the amount of radioiron lost. It is thus probable that the observed losses of radioiron reflect a physiological mechanism which regulates iron absorption.