Relationship between absorption of inorganic and food iron in field studies

Food iron absorption data on 853 Indian women were compared to the haemoglobin concentrations, other iron-related measurements and the absorption of a reference dose of 3 mg iron given as ferrous ascorbate. The serum ferritin concentration was identified as the best predictor of the absorption of the reference dose (r = -0.54, p less than 0.0001). These two measurements were then compared in terms of their relative ability to predict the absorption of iron from 10 individual meals. Results were comparable, with correlations for the pooled data of -0.50 (p less than 0.0001) for the serum ferritin and 0.47 (p less than 0.0001) for the reference dose. Since serum ferritin is a simple and non-invasive test, it may represent the more satisfactory way of standardising food iron absorption results to a common iron status in field studies. However, the value of such an approach is limited by the wide confidence limits of the relationship between food iron absorption and both the other measurements.