Absorption of carbonyl iron.

The mechanism of carbonyl iron absorption has been studied in rats. Solubilization by gastric acid was a prerequisite for subsequent absorption. The slow rate of solubilization resulted in a more prolonged absorption, responsible for the low toxicity of carbonyl iron. Large doses of carbonyl iron were held for several days by the gastric mucosa of iron-deficient animals. Once it had been solubilized, the subsequent pathway of absorption by the intestinal mucosa and the amount absorbed was similar to that of ferrous ammonium sulfate.