Feeding of iron (Fe)-fortified (12-15 mg/L) infant formulas is an effective and convenient means to protect infants from Fe deficiency. To study lower levels of Fe fortification of infant formulas (3 or 6 mg/L) compared with those currently in use, we compared Fe intake and Fe nutritional status of three groups of healthy, term infants between 90 and 274 days of age. One group received an Fe-fortified whey-predominant formula (3 mg/L) and the second group received the same formula with a higher Fe level (6 mg/L). A comparison group was breast-fed at least until 274 days of age. All infants received infant foods and cereals according to European Community recommendations. Mean Fe intake of infants fed formula fortified with 3 mg/L was significantly lower at 183 and 274 days of age (p < 0.05) than that of infants fed formula fortified with 6 mg/L. None of the infants fed the formula fortified with 3 mg/L met the recommended daily allowance value (10 mg) for infants between 6 and 12 months of age. Hemoglobin, hematocrit, mean corpuscular volume, free erythrocyte protoporphyrin, and serum ferritin levels were similar in the formula-fed groups; none of the infants had depleted Fe stores (ferritin < 10 micrograms/L) at 183 and 274 days of age. Thirteen percent of breast-fed infants had depleted Fe stores at 183 days of age, but only 3% were depleted at 273 days of age, when Fe-fortified beikost was already part of the diet. No influence of Fe nutritional status was found on zinc and copper nutritional status or on growth.(ABSTRACT TRUNCATED AT 250 WORDS)