ASCORBIC-ACID ENHANCES HYDROXYL RADICAL FORMATION IN IRON-FORTIFIED INFANT CEREALS AND INFANT FORMULAS

Infant cereals and formulas are usually fortified with iron to prevent iron deficiency. To enhance iron bioavailability, supplemental ascorb ic acid is recommended. Ascorbic acid is considered to be an antioxida nt in vivo, but has pro-oxidant effects when exposed to non-protein-bo und iron. We measured formation of free radicals in cereals and infant formulas after addition of ascorbic acid. The production of hydroxyl radicals was assessed by hydroxylation of salicylic acid to 2,5-dihydr oxybenzoic acid (2,5-DHBA). Production of 2,5-DHBA increased with incr easing ascorbic acid doses added. Addition of 0.8 mM ascorbic acid to breast milk produced less radicals (0.03 +/- 0.05 mu M) than addition of ascorbic acid to low-iron formula (0.13 +/- 0.08 mu M, P = 0.019), medium-iron formula (0.34 +/- 0.12 mu M, P < 0.0001) or high-iron form ula (0.44 +/- 0.08 mu M P < 0.0001). Even when iron content in breast milk was adjusted to a level comparable with that of formulas, product ion of 2,5-DHBA was lower. Breast milk seems to contain substances tha t reduce hydroxyl radical formation. Conclusion Supplemental ascorbic acid causes hydroxyl radical formation in iron-fortified infant nutrie nts in vitro.