Gastrointestinal blood loss in older infants: impact of cow milk versus formula.

Concerns that consumption of whole cow milk (WCM) by older infants may result in excessive gastrointestinal blood loss and subsequent iron deficiency led us to perform a prospective, randomized study in 104 infants. Infants were assigned to receive WCM beginning at 6 months or one of three formulas beginning at 4-6 months of age and followed until 12 months of age. Gastrointestinal blood loss was similar for all groups, as determined by both qualitative (Hemoccult II) and quantitative testing (HemoQuant). There was no association between concentration of fecal hemoglobin and volume of WCM consumed or iron status by 12 months of age. Of eight infants (seven WCM, one formula) who became iron-depleted, none had excessive fecal hemoglobin excretion. When pooled and analyzed regardless of feeding group, fecal hemoglobin increased with age and was greater at 11 and 12 months than at younger ages. We conclude that although infants fed WCM are at increased risk of developing iron depletion, the iron insufficiency is not due to gastrointestinal blood loss. We further conclude, based on our sample of normal infants age 4-12 months, that fecal hemoglobin concentrations of 0.5-0.8 mg/g stool correspond to the upper limits of normal, values much lower than in adults.