MILK INHIBITS AND ASCORBIC-ACID FAVORS FERROUS BIS-GLYCINE CHELATE BIOAVAILABILITY IN HUMANS

The chemical properties of ferrous bis-glycine chelate allow for its u se as a fortificant in fluid, high fat vehicles. This chemical form ma y also protect iron from the inhibitory or enhancing effects of the di et on iron absorption. Alternatively, iron bis-glycine chelate may be absorbed by a mechanism independent of an individual's iron stores. To test these hypotheses, the bioavailability of iron bis-glycine chelat e added to water and milk was studied using a double-isotopic method i n two groups of 14 women. Iron absorption from aqueous solutions of 0. 27 mmol/L (15 mg/L) of elemental iron as either iron bis-glycine or fe rrous ascorbate was not significantly different (34.6 and 29.9%, respe ctively). There were significant correlations between (log) iron absor ption of iron bis-glycine with (log) serum ferritin (r = -0.60, P < 0. 03) and with (log) iron absorption from ferrous ascorbate (r = 0.71, P < 0.006), suggesting that iron bis-glycine chelate bioavailability is indeed affected by iron stores. Iron absorption of iron bis-glycine g iven in milk was significantly lower (P < 0.002) than when given in wa ter, with values of 11.1 and 46.3%, respectively (standardized to 40% absorption of the reference dose). With the addition of 0.57 mmol/L as corbic acid (100 mg/L), iron absorption of iron bis-glycine given in m ilk increased significantly from 11.1 to 15.4% (P < 0.05). These findi ngs show that milk and ascorbic acid affect iron bis-glycine chelate b ioavailability and also demonstrate that iron stores may influence its bioavailability as well. The good bioavailability of iron bis-glycine makes this compound a suitable alternative to be considered in iron f ortification programs.