Iron sufficiency with prolonged exclusive breast-feeding in Peruvian infants.

Serum ferritin and erythrocyte porphyrin concentrations were measured in seven Peruvian infants, who ranged in age from 7.5-12.0 months (mean: 9.3 months), who had been exclusively breast-fed all their lives. No infant had evidence of iron deficiency as reflected by a reduced serum ferritin, or an increased erythrocyte porphyrin. Mean serum ferritin and erythrocyte porphyrin values in these seven infants were similar to those of 40 nonanemic, noniron-deficient U.S. infants who ranged in age from 9 to 12 months, on a mixed diet. These findings illustrate that exclusively breast-feeding an infant for at least 9 months of life meets the iron requirements of the full-term infant.