Objective: To calculate iron stores in man and their rates of changes
in relation to iron requirements and dietary iron intake and bioavaila
bility. Method: Newly established relationships between iron absorptio
n from whole diets and serum ferritin (SF) and between SF and iron sto
res allow calculations of amounts of stored iron under different condi
tions (diets, losses) at stationary states when absorption equals loss
es. Rate of growth of stores can also be calculated. All calculations
are based on observations and require no model assumptions. Results: P
resent calculations of iron stores agree with previously observed phle
botomy values. Differences in intake and bioavailability of dietary ir
on and in iron requirements had marked effects on amounts of stored ir
on. A wide range of diets was studied, from a hypothetical high-meat d
iet typical for early man to diets in developing countries. A new equa
tion is given for the Translation of SF into iron stores. Analyses of
growth rate of stores under different conditions showed a fast growth
from zero iron stores during the first year (reaching about 80% of fin
al amounts) followed by a much slower rate for 2-3 y. A marked inertia
was seen in rate of changes in iron stores that was more marked the c
loser stores were to their stationary states making it difficult to us
e SF to estimate short term changes in iron absorption in iron replete
subjects. Conclusions: Realistic Western-type diets with good bioavai
lability can cover iron requirements in most women and can restitute i
ron stores during lactation. The high prevalence of iron deficiency in
menstruating Western women is thus mainly related to a further low bi
oavailability of iron in present diets. Present analyses also demonstr
ated an effective control of iron absorption preventing development of
iron overload in otherwise healthy subjects even if the diet is forti
fied with iron and even if meat intake is high.