Provided is a composition and method for modulating serotonergic receptor expression, reducing anxiety-like behavior and stress-induced inflammatory response in a pediatric subject, the method including administering to the pediatric subject a nutritional composition including lactoferrin from a non-human source and a prebiotic composition including polydextrose and/or galactooligosaccharides. Further provided is a method for reducing constipation in a pediatric subject by providing a nutritional composition including lactoferrin from a non-human source and a prebiotic composition including polydextrose and/or galactooligosaccharides.