Iron absorption from ferritin and ferric hydroxide.

Ferritin and ferric hydroxide represent two forms of iron which are less available for absorption than that present in the 'common pool' of non-haem dietary iron. In the present study the absorption of iron from these two compounds was compared in 35 multiparous women when fed in water, in maize porridge and in maize porridge containing 100 mg ascorbic acid. The geometric mean absorption for 3 mg ferritin iron was 0.7% and for ferric hydroxide, 2.4%. Comparable figures when fed with maize porridge were 0.4% and 0.4% respectively. When 100 mg ascorbic acid was present in the porridge, absorption was enhanced from both sources, being 12.1% for ferritin and 10.5% for ferric hydroxide. These results indicate that the fraction of iron in ferritin and ferric hydroxide that enters the 'common pool' of non-haem dietary iron is profoundly influenced by the nature of the diet. The greater the concentration of enhancing ligands, the closer does the absorption of iron from these compounds approximate that of the non-haem dietary iron pool.