Ferrous Ammonium Phosphate

Ferrous ammonium phosphate consists of iron(II), ammonium and phosphate ions in a 1:1:1 molar ratio, with the iron content ranging between 24% and 30%. Ferrous ammonium phosphate is intended for use as an alternative to currently permitted iron fortification compounds. Ferrous ammonium phosphate is stable in foods but readily dissociates to iron(II), ammonium and phosphate ions when subjected to the low pH conditions of the stomach.1


Ferrous ammonium phosphate is manufactured by mixing phosphoric acid, iron powder and ammonium hydroxide. Iron powder and phosphoric acid are combined in demineralized water with stirring to form a suspension. The mixture is heated until no further gas is evolved. Ammonia solution is added to the resultant slurry to yield ferrous ammonium phosphate. The product is then spray dried and milled to obtain a greyish-green fine powder.

On the basis of the available data on the bioavailability of iron from ferrous ammonium phosphate and consideration of the toxicity of its constituent ions, it has been concluded that ferrous ammonium phosphate is acceptable for use as a source of iron for dietary fortification, provided that the total intake of iron does not exceed the dosage for iron of 0.8 mg/kg body weight.