Iron(II) glycinate

Iron glycinate refers to an iron complex of glycinate. Such species are transition metal amino acid complexes. Some compositions are used as dietary supplements and in food fortification in the place of other sources of iron, often under the trademark Ferrochel. It is sometimes sold as a hydrochloride salt.

Structure

The structure of one glycinate complex of iron has been determined by X-ray crystallography. The octahedral complex features two bidentate glycinate ligands as well as two aquo ligands.

Synthesis

Iron glycinate is claimed to form when iron powder is treated with a two-fold molar excess of glycine in a citric acid solution. The citric acid acts as an antioxidant to prevent oxidation of Fe to the more insoluble and therefore less bioavailable Fe form:
Commercial formulations retain the citric acid as a preservative, and include silicon dioxide and maltodextrin.

Safety

Since 2001, iron glycinate has been generally regarded as safe by the Food and Drug Administration, with a No Observable Adverse Effect Level of at least 500 mg kg^-1 rat body weight. Compared to other iron salts, such as iron sulfate, it is associated with fewer adverse gastrointestinal effects and a higher bioavailability. For these reasons, it is a promising supplement for those with iron-deficieny anaemia, and has shown significant increases in plasma ferritin, a protein that stores iron.
The European Food Safety Authority has evaluated ferrous bisglycinate for use in foods and supplements.