IRON STORES IN MAN IN RELATION TO DIET AND IRON REQUIREMENTS

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.