Prebiotic Galacto-Oligosaccharides and Fructo-Oligosaccharides, but Not Acacia Gum, Increase Iron Absorption from a Single High-Dose Ferrous Fumarate Supplement in Iron-Depleted Women.

BACKGROUND: Prebiotic galacto-oligosaccharides (GOS) increase iron absorption from fortification-level iron doses given as ferrous fumarate (FeFum) in women and children. Whether GOS or other fibers, such as prebiotic fructo-oligosaccharides (FOS) and acacia gum, increase iron absorption from higher supplemental doses of FeFum is unclear. OBJECTIVES: In iron-depleted [serum ferritin (SF) <25 μg/L] women, we tested if oral coadministration of 15 g GOS, FOS, or acacia gum increased iron absorption from a 100 mg Fe supplement given as FeFum. METHODS: In a randomized, single-blind, crossover study, 30 women (median age: 26.2 y; median SF: 12.9 μg/L) consumed a 100 mg Fe tablet labeled with 4 mg 57Fe or 58Fe, given with either 1) 15 g GOS; 2) 15 g FOS; 3) 15 g acacia gum; or 4) 6.1 g lactose and 1.5 g sucrose (control; matching the amounts of sucrose and lactose present in the GOS powder providing 15 g GOS), dissolved in water. The primary outcome, fractional iron absorption (FIA), was assessed by erythrocyte isotopic incorporation 14 d after administration. Data were analyzed using a linear mixed-effect model. We also tested, in vitro, iron solubility at different pH and dialyzability from the different supplement combinations administered in vivo. RESULTS: FIA from FeFum given with GOS and FOS was significantly higher (+45% and +51%, respectively; P