Absorption of di- and trivalent iron. Experimental evidence

The present experiments were carried out on normal and iron deficient rats which were fed low iron diet and bled several times; the haemoglobin content of blood of normal rats was in the range of 12-14 g/dl, that of iron deficient rats between 6 and 8 g/dl. Iron was administered by a gastric tube and the retention of the radioactively labelled 59Fe-iron compounds was measured on the 6th day after the administration. There is no difference of the absorption of divalent and trivalent iron provided iron is administered in ionized form. This is possible when the iron solution administered is of pH less than 2.5. Since the pH values of gastric juice is in the same order of magnitude, this procedure is hardly to be called unphysiological. The decisive role of pH for the bioavailability of iron ions can be derived from an experiment with cobaltous ions that, in the range of physiological pH values, cannot be hydrolysed. Therefore, no difference of the retention of cobaltous ions was measured regardless whether the solution administered into a tied-off jejunal loop was of pH 2 or 5.5. The administration of either divalent or trivalent iron ions together with food to normal rats is followed by a slight decrease of the amount of iron retained. However, this difference of retention disappears when the ionized iron is administered to fed iron deficient rats.(ABSTRACT TRUNCATED AT 250 WORDS)