Procedures: A randomized, controlled dietary intervention trial among lactating women comparing the effects of a Mediterranean-style diet with walnuts to the USDA's MyPyramid Diet for Moms was commenced to determine the effects of the diet on fatty acid profiles and biomarkers of inflammation in breast milk and material serum/plasma. Secondary outcomes of interest include effects of maternal diet assignment on maternal body weight and body composition as well as infants' growth and health during the study trial period.