Breastfeeding provided by healthy and well-nourished mothers is considered the ideal nourishment for healthy term infants and is believed to cover the infant's nutrient requirements during the first 6 months of life. Breast milk composition varies with time postpartum, during nursing, and with maternal nutrition. The changes of human milk composition with time of lactation seem to match the changing needs of growing infant over time. At a certain age, however, breast milk alone no longer can supply all of the infant's nutritional requirements, and complementary foods and/or supplementation of nutrients are needed to ensure adequate nutrition and growth. The nutritional status of lactating mothers is an important health issue since their nutrition status may influence the nutrient concentration of breast milk, while maintaining the nutrients in the breast milk further depletes their own body store. This review discusses the contribution of breast milk to nutritional needs during infancy, growth patterns of breastfed infants, and recommendations regarding the use of complementary foods and nutrient supplementation. In addition, we also review the effect of maternal nutrition on breastfeeding and the nutritional recommendation for lactating women.