The focus of this chapter is to discuss the nutritional requirements of individuals in different periods of life, spanning from infancy and childhood to old age. We start with the pregnancy and maternal nutritional needs, which ultimately determine fetal growth and development. We continue by addressing the main issues in infancy, childhood, and adolescence, focusing on the critical nutrients in each period, dietary patterns and behaviors, and most common disorders associated with food intake in those periods. Adult period focuses on the balanced nutrition and lifestyle conducive to disease prevention and maintenance of healthy state. The section on older adults addresses some of the most critical nutrients for that period, as well as some chronic conditions and the ways to avoid or alleviate them.