Food: the primary source of energy and nutrients
The science of nutrition concerns itself with the study of food and the way in which food consumption affects health. This means we need to combine knowledge of how the components in food link in with the functions of the body, which in turn means going right down to the chemical structures of components within foods. It also means understanding how they interact with biochemical pathways in the body, and how this interacts with the functioning of the body (physiology). The term 'nutrients' describes components in food that we have known about for some time as more or less essential for survival. Scientists are continually discovering many other components in food, but this chapter will focus on the main nutrients. The lifecycle of the human body is represented through stages of early development and growth through to maturation and senescence. Functional capacities and nutritional needs vary throughout these stages depending on a number of conditions. This chapter focuses on the general principles of food utilisation and nutrient requirements.