CAPACITY OF THE STORE-REGULATOR IN MAINTAINING IRON BALANCE

There is evidence that iron stores alter iron absorption to meet body iron needs. In this study, quantitative aspects of this regulation of iron balance are examined. Two male subjects, one with low and one wit h average iron stores, were given additional dietary iron over 500 day s. Changes in iron stores were monitored by plasma ferritin measuremen ts, and the ferritin estimate of stores was validated at the end of th e study by bleeding to the point of iron deficiency. The subject with low iron stores increased his ferritin by 39 mu g/L or 0.8 mg/day, whe reas the subject with average iron stores had no significant change. I t is concluded that the mechanism by which stores regulate food iron a bsorption has a capacity of about 1 mg/day, sufficient to meet usual p hysiological needs, with the exception of pregnancy, as well as the ab ility to resist increase in stores above normal despite an iron rich d iet, (C) 1994 Wiley-Liss, Inc.