L. Hallberg et al., IRON-ABSORPTION FROM THE WHOLE DIET IN MEN - HOW EFFECTIVE IS THE REGULATION OF IRON-ABSORPTION, The American journal of clinical nutrition, 66(2), 1997, pp. 347-356
Iron absorption from the whole diet, which contained a highly bioavail
able form of iron, was measured for 5 d in 31 healthy men, including 1
2 blood donors. Nonheme iron in all meals was labeled with an extrinsi
c, inorganic radioiron tracer added in amounts to ensure uniform Speci
fic activity in all meals. Heme iron was labeled similarly by using he
moglobin biosynthetically labeled with another radioiron tracer. There
was a good inverse relation between total absorption and concentratio
n of serum ferritin up to approximate to 60 mu g/L. In subjects with s
erum ferritin > 60 mu g/L there was no relation to iron absorption. At
this serum ferritin concentration, absorption decreased to a level ju
st sufficient to cover basal iron losses, implying that at a serum fer
ritin concentration greater than or equal to 60 mu g/L no further accu
mulation of iron stores will occur by dietary iron absorption. The fin
dings thus suggest that in normal subjects there is no risk of develop
ing iron overload by iron absorption from the diet even if the diet is
fortified. Similar findings were made previously in two studies in wo
men, both of which indicated an effective control of absorption. At th
e same serum ferritin concentration the absorption per kilogram body w
eight was the same in men and women served identical diets with a high
iron bioavailability. These new observations strongly suggest that tr
anslation of serum ferritin concentration into amounts of stored iron
should be made with caution and that in subjects with high serum ferri
tin concentrations, other causes than increased iron stores should be
considered. There was effective control of both heme- and nonheme-iron
absorption but their relations to iron status were different.