Evaluation of two iron-fortified, milk-based formulas during infancy.

Objective: Compare milk-based, iron-fortified formulas containing 7.4 and 12.7 mg/L iron and breast-feeding during the first year of life.

Design: Partially randomized, double-blind trial: non-breast-fed infants randomly assigned to receive one of two coded formulas, identical except for iron content; infants discontinuing breast-feeding between 1 and 8 weeks of age randomly assigned to a formula late-start group.

Setting: Five general community pediatric practices in Missouri, Indiana, Illinois, and Pennsylvania.

Participants: Sample of 347 healthy, term infants, enrolled within 1 week after birth; 172 included in statistical analyses.

Outcome Measures: Length, weight, and indicators of formula intolerance recorded at clinic visits; formula consumption, bowel movements, stool consistency, and other tolerance indicators recorded by parents on daily and weekly report forms; hemoglobin, hematocrit, and serum ferritin, iron zinc, and copper measured at 6 and 12 months.

Results: No significant differences between formula-fed groups in growth, attrition, formula consumption, bowel movements, hematocrit, hemoglobin level, and serum iron, zinc, and copper levels (P > .05); first 6-month weight and length changes of the breast-fed group significantly less than in both formula-fed groups (P < .008); serum ferritin level of the formula-fed, high-iron group significantly higher than that of the low-iron and breast-fed groups (P < .008), although all groups' values were normal; no apparent differences between formula groups in formula tolerance and stool characteristics but data were not analyzed statistically.

Conclusions: Milk-based formulas containing either 7.4 or 12.7 mg/L iron support normal growth and iron status of healthy, term, normally fed infants during the first year and both are well tolerated and accepted.