RISK OF DIARRHEA RELATED TO IRON CONTENT OF INFANT FORMULA - LACK OF EVIDENCE TO SUPPORT THE USE OF LOW-IRON FORMULA AS A SUPPLEMENT FOR BREAST-FED INFANTS

Background. Concern has been raised by infant feeding experts that sup plementing breastfed infants with iron-fortified formula rather than l ow-iron formula may have an undesirable impact on their gastrointestin al flora. Thus far, there have been no clinical studies to address thi s issue directly. We compared the reported frequency of diarrhea for b reastfed infants given iron-fortified formula with those fed low-iron formula. Methods. Mothers participating in a mail panel provided feedi ng and diarrhea information on their infants at 2, 3, 4, 5, 6, 7, 9, a nd 12 months (n = 1743). Infants were grouped into five feeding catego ries: (1) breast milk only, (2) breast milk and low-iron formula, (3) breast milk and iron-fortified formula, (4) low-iron formula only, and (5) iron-fortified formula only. We calculated the number of diarrhea l episodes per week for each feeding category and used rate ratios to estimate the relative impact of low-iron and iron-fortified formulas. Results. Among infants who received both breast milk and formula, the rate ratio for iron-fortified formula versus low-iron formula was 1.06 (confidence interval, 0.84 to 1.34), indicating that the type of form ula a breastfed infant receives does not significantly affect the freq uency of diarrhea. Conclusions. We found no evidence to support the hy pothesis that breastfed infants given iron-fortified formula are at gr eater risk of having diarrhea. This, in addition to the fact that iron -fortified formula has played a major role in preventing childhood iro n deficiency anemia, supports the current recommendation that any form ula given to infants be fortified with iron.