RecruitingClinical trialWalnuts as an Infant Solid Food for HealthThe objective is to investigate the effect of walnuts on gut microbiota, inflammatory markers, atopic dermatitis status, and indices of allergy outcomes in breastfed infants during early complementary feeding. The three primary aims include: Aim 1: Evaluate the effect of walnut consumption on gut microbiota structure and function, inflammation, atopic dermatitis, and allergy outcomes. Aim 2: Evaluate the impact of walnut consumption on infant growth trajectories and risk of overweight. Aim 3 (exploratory): Identify walnut-specific food signatures that are associated with gut microbiota and immunity biomarkers using a novel nutri-metabolomics technique.