Determination of iron absorption from whole diet

Preliminary data strongly indicate that there is a complete isotopic exchange between an added inorganic iron tracer and non‐haem iron compounds in a number of foodstuffs when thoroughly mixed with the food during preparation. The absorption of such a tracer is expected to give a true measure of the total absorption of non‐haem iron from the diet. Similarly there is evidence indicating that radioiron labelled haemoglobin may be used as a tracer for studies on haem iron absorption from the diet. A two‐pool model is suggested for food iron absorption — one haem iron and one non‐haem iron pool. These pools can be independently labelled with an inorganic radioiron tracer and with radioiron labelled haemoglobin by using two different radioiron isotopes. The total absorption of iron from these pools — from the whole diet — can be measured from the combined measurement of total body retention of 59 Fe using whole body counting and determination of the ratio 55 Fe/ 59 Fe in a blood sample. A report of preliminary studies on the application of this method in normal and iron deficient men is also given.