Iron stores and haemoglobin iron deficits in menstruating women. Calculations based on variations in iron requirements and bioavailability of dietary iron

Abstract

Background: Iron stores and haemoglobin iron deficits in menstruating women can be calculated from body iron losses and absorption of dietary iron using recently developed methods.

Objective: To examine iron balance (iron status) expressed as body iron stores or haemoglobin iron deficites in menstruating women from amounts of iron lost (iron requirements) and amounts of dietary iron absorbed. Calculations are made both of stationary states and of the rate of changes in iron stores (iron status) when any of the two main factors determining iron balance are changed.

Design: The study is based on (1) previous and new equations describing relationships between iron absorption, iron requirements (losses), iron stores and/or haemoglobin deficits and (2) published data on iron requirements and their variation in menstruating adult women.

Results: Both iron stores and haemoglobin iron deficits are strongly related to iron requirements and absorption of dietary iron and follow the same equations during states of iron repletion and iron deficiency. When, for example, increasing or decreasing the bioavailability of the dietary iron, about 90% of the change in iron stores will occur within 1 y.

Conclusions: There are strong relationships between iron requirements, bioavailability of dietary iron and amounts of stored iron. The observations that a reduction in iron stores and a calculated decrease of haemoglobin iron had the same increasing effect on iron absorption suggest that the control of iron absorption is mediated from a common cell, that may register both size of iron stores and hemoglobin iron deficit, eg the hepatocyte.

Sponsorship: The Swedish Medical Research Council ( project B96-19X-04721-21A), the Swedish Council for Forestry and Agriculture Research (50.0120/95 and 997/881, 113:3), the Swedish Dairy Association and The Danone International Prize for Nutrition 1999 (LH).

European Journal of Clinical Nutrition (2000) 54, 650–657.