In this chapter, we approach nutrition from both a personal perspective and a molecular structure point of view. We begin with an examination of what we eat and why we eat. This leads to a general consideration of the three main classes of food components: carbohydrates, fats, and proteins. Sources of these macronutrients are considered and we examine the current dietary recommendations for these three groups. What follows is a series of sections that investigate carbohydrates, fats, and proteins in considerably greater detail. In every case, we devote particular attention to molecular structure and its relationship to properties and functions. And we also include individual and public health issues. Sugars, starches, and other carbohydrates are discussed, and lactose intolerance is treated briefly. Our study of fats includes information about saturated and unsaturated fats and oils, dietary cholesterol and heart disease. The two sections on proteins treat such topics as amino acids, phenylketonuria, and the importance of a complete diet, one with adequate essential amino acids.

Because food is the source of the energy that powers our bodies and our brains, we next consider the caloric content of various foods, the recommended food energy intake for men and women of various ages and weights, and the energy expenditures associated with a number of activities. But calories are not enough to ensure a balanced diet, which also requires the correct amounts of a wide array of vitamins and minerals. Therefore, we devote individual sections to the roles of a few of these micronutrients and the hazards of an insufficient or an excessive supply of them. The chapter concludes with a consideration of how food supplies are preserved, including the use of gamma radiation, a controversial technology in the eyes of some critics. The chapter contains a wide range of information, but our goals are straightforward: (1) to help you see the connection between chemistry and nutrition by applying chemical principles in the context of the composition and reactions of foodstuffs; (2) to provide information that you can use in making daily choices about personal nutrition and health; and (3) to analyze a number of nutrition-related controversies that have appeared in the popular press.