A new area of nutritional research in pediatrics is potential immunonutrition in critically ill children with enteral nutrition. Formulae are enriched with single components or a combination of key substrates that might play a crucial role during intermediary metabolism in sepsis, inflammation, tissue healing and growth. Pharmaconutrition is an extended concept where single components are investigated in a stepwise scientific procedure in order to identify effective disease-dedicated nutrition therapy. Any new formula needs to be evaluated, if possible in comparison to a normal diet or the reference formulation to demonstrate its safety and efficacy (equal or superior to standard formula). Finally, nutrigenomics refers to the findings that nutrients directly or indirectly alter gene expression in enterocytes, cytokine release and modulate immune function within and outside the gut.