Oxidative stress in healthy breast fed versus formula fed infants

Polyunsaturated fatty acids (PUFA), major substrates for lipid peroxidation , have been associated with enhanced oxidative injury. Infants fed solely o n breast milk (BM) and infants fed cow's milk modified formulas (F), differ in amount and composition of dietary fatty acids (FA). A major difference relates to breast milk's content of long chain PUFA [C 20-22] which are hig hly susceptible to peroxidation. In healthy infants, 13 on BM and 13 on F, plasma lipid peroxidation products were determined using TBAR's method and plasma antioxidant capacity evaluated by cyclic voltammetry (CV). Mean age, weight [expressed as % of 50th percentile for age] and hemoglobin levels d id not differ between the two groups. Results of the TBARs assay were expre ssed as malondialdehyde equivalent content nmol MDA/ml plasma: in BM-fed in fants 5.87+/-0.56 (mean +/- s. error) vs. 2.34+/-0.11 in F-fed infants (p<0 .001). CV of plasma samples demonstrated uniform peak potential (330 mV) an d similar anodic current (4.82 mu A+0.7 vs. 4.91 mu A+/-0.9) denoting that type and concentration of antioxidants do not differ between groups. Thus, compared to F-fed infants, BM-fed infants exhibit increased peroxidative in jury in presence of similar antioxidant capacity. As BM is the "gold standa rd" of optimal infant nutrition it is difficult to concede to its potential deleterious effects. Rather, based on observations linking oxygen tension with biological processes of maturation and suggestions that intracellular PUFA scavenge oxygen radicals, it is intriguing to speculate as to the phys iological role of oxidants and PUFA in early life. (C) 1999 Elsevier Scienc e Inc.