1 School of Public Health, University of California, 19 Earle Warren Hall, Berkeley, CA 94720
To the Editor.
Janas et al1 have reported on differences in biochemical indices of protein utilization in infants who were breastfed compared with those fed two types of cow's milk formula. Their finding of elevated plasma amino acid and serum urea nitrogen concentrations in formula-fed infants is an important confirmation of previous studies on term infants by Järvenpää et al.2 However, their results and conclusions about total dietary intake of protein, nitrogen, and amino acids are problematic due to their study design and methods.