BIOAVAILABILITY OF IRON GLYCINE AS A FORTIFICANT IN INFANT FOODS

The bioavailability of iron glycine added to a vegetable infant weanin g food was compared with ferrous sulfate. Stable, isotopically labeled compounds (Fe-57 or Fe-58) were mixed into the midday meal (1.4 mg ad ded Fe/serving) and fed to 9-mo-old infants on alternate days for 8 d. Bioavailability, expressed as a percentage of the dose consumed, was measured from isotopic enrichment of hemoglobin 14 d after the last te st meal. There was no difference between iron glycine and ferrous sulf ate ((x) over bar +/- SEM): 9.0 +/- 0.7% and 9.9 +/- 0.8%, respectivel y. The effect of chelation was examined by measuring iron bioavailabil ity of iron glycine and ferrous sulfate added to a high-phytate (310 m g/100 g) whole-grain cereal weaning food and comparing it with a lower -phytate (147 mg/100 g) vegetable food, as used in the first study. Bo th iron compounds had lower bioavailability from the high-phytate food , 5.2 +/- 0.5% for iron glycine and 3.8 +/- 0.9% for ferrous sulfate, than the lower-phytate food, 9.8 +/- 1.5% for iron glycine and 9.1 +/- 1.3% for ferrous sulfate. The results showed no significant differenc e in bioavailability between the two forms of iron when added to infan t weaning foods, suggesting that the glycine complex was fully or part ially dissociated in the gastrointestinal tract. It is concluded that chelation does not improve the bioavailability of iron in the presence of dietary inhibitors.