Birth is an event that exposes the newborn baby to a high concentration of free radicals (reactive oxygen species (ROS)/reactive nitrogen species (RNS)), which can contribute to several diseases. The balanced equilibrium between ROS/RNS and the antioxidant system of the newborn is a key factor in preventing a plethora of diseases. The antioxidant system involves endogenous and exogenous molecules, from vitamins (A, E, C) to enzymes (glutathione peroxidase, superoxide dismutase), metals (copper, zinc, and selenium) and other molecules (coenzyme Q10, melatonin) that can act in a synergistic manner to deactivate free radicals. A competent antioxidant system of the baby is strongly dependent on the intake of free radical deactivating molecules from feeding, either maternal or formula milk, with several studies pointing that breast milk has more powerful antioxidant effects on lowering the infant's oxidative status. An improved understanding of the antioxidant molecules, their mechanism of action, and the relationships between them, are key factors to comprehend all the potential benefits of human breastfeeding in this matter. The purpose of this review is to describe different research efforts and methodologies of evaluation of TAS in human milk, and to evaluate and summarize the contribution of different antioxidant molecules.

Departamento de Pediatria da Faculdade de Medicina da Universidade do Porto Serviço de Pediatria HPI Centro Hospitalar de São João Alameda Prof Hernâni Monteiro P 4202 451 Porto Portugal

FP ENAS Universidade Fernando Pessoa Rua Carlos da Maia 296 P 4200 150 Porto Portugal

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