Effect of ascorbic acid and particle size on iron absorption from ferric pyrophosphate in adult women

Meredith C. Fidler, Lena Davidsson, Christophe Zeder, Thomas Walczyk, Irene Marti, Richard F. Hurrell

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The effects of added ascorbic acid and particle size on iron absorption from ferric pyrophosphate were evaluated in adult women (9-10 women/study) based on erythrocyte incorporation of iron stable isotopes (57Fe or 58Fe) 14 days after administration. Three separate studies were made with test meals of iron-fortified infant cereal (5 mg iron/meal) and the results are presented as geometric means and relative bioavailability values (RBV, FeSO4 = 100%). The results of study 1 showed that iron absorption was significantly lower from ferric pyrophosphate (mean particle size 8.5 μm) than from FeSO4 in meals without ascorbic acid (0.9 vs. 2.6%, p < 0.0001, RBV 36%) and in the same meals with ascorbic acid added at a 4:1 molar ratio relative to fortification iron (2.3 vs. 9.7%, p < 0.0001, RBV 23%). Ascorbic acid increased iron absorption from ferric pyrophosphate slightly less (2.6-fold) than from FeSO4 (3.7-fold) (p < 0.05). In studies 2 and 3, RBV of ferric pyrophosphate with an average particle size of 6.7 μm and 12.5 μm was not significantly different at 52 and 42% (p > 0.05), respectively. In conclusion, the addition of ascorbic acid increased fractional iron absorption from ferric pyrophosphate significantly, but to a lesser extent than from FeSO4. Decreasing the mean particle size to 6.7 μm did not significantly increase iron absorption from ferric pyrophosphate.

Original languageEnglish
Pages (from-to)294-300
Number of pages7
JournalInternational Journal for Vitamin and Nutrition Research
Issue number4
Publication statusPublished - 1 Jul 2004



  • Ascorbic acid
  • Ferric pyrophosphate
  • Food fortification
  • Humans
  • Iron absorption
  • Particle size
  • Stable isotopes

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