Ferric pyrophosphate

Scheuchzer P, et al. The Journal of Nutrition, 2023, 153(3), 636-644.

This study investigated the use of ferric pyrophosphate (FePP) in co-extruded rice to enhance iron solubility and bioavailability in young women. Rice was fortified with FePP in combination with solubilizing agents, including citric acid/trisodium citrate (CA/TSC), ethylenediaminetetraacetic acid (EDTA), or sodium pyrophosphate (NaPP), and zinc compounds (ZnSO₄ or ZnO). Labeled ⁵⁷FePP was employed to trace iron absorption, while electron paramagnetic resonance (EPR) characterized the formation of high-spin Fe(III) coordination complexes with weak ligand fields. In vitro assays quantified iron solubility, and fractional iron absorption (FIA) was determined in 21 healthy young women (mean age 22 ± 2 y; BMI 21.3 ± 1.5 kg/m²; plasma ferritin 28.5 μg/L), with comparisons to ferrous sulfate (⁵⁸FeSO₄) using linear mixed-effect models. Results demonstrated that co-extrusion with zinc and solubilizers generated bioavailable iron coordination complexes, with FIA ranging 9-11%, comparable to FeSO₄. Phytic acid reduced absorption from FePP + CA/TSC rice by 50%, indicating similar inhibitory effects as observed with FeSO₄. The study confirmed that FePP + NaPP, as well as FePP + EDTA with zinc, are viable strategies for rice fortification, offering experimental evidence of iron-ligand interactions that enhance solubility and human bioavailability.