Oxidative activity and dialyzability of some iron compounds under conditions of a simulated gastrointestinal digestion in the presence of phytate

The oxidative activity of some iron compounds was compared under conditions of gastrointestinal digestion and correlated with iron solubility and dialyzability. Ferric chloride, NaFeEDTA, ferrous bis-glycinate, ferrous gluconate, or ferrous lactate, were mixed with water or a phytate solution or a phytate solution treated with phytase and digested in vitro. The dialyzable and the non-dialyzable fractions of the digests were analyzed for oxidative activity on linoleic acid liposomes and iron solubility and dialyzability. In all dialyzable and non-dialyzable fractions, oxidative activity was variable in water (P < 0.05), lower and similar for all iron compounds in phytate (P < 0.05), higher and variable in phytate solutions treated with phytase (P < 0.05). In most digests, ferric chloride was least active, followed by ferrous lactate, NaFeEDTA and ferrous bis-glycinate. There was no correlation between oxidative activity and iron dialyzability or solubility. These results point to variable oxidative properties that iron compounds may potentially exhibit in the lumen. (c) 2006 Elsevier Ltd. All rights reserved.