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The role of nutrition in public health and preventive medicine is self-evident: people must eat to live. Both inadequate and excessive food intake can adversely affect health, and both contribute to the leading causes of morbidity and mortality in every nation, developing as well as industrialized. Because all people consume food, all have an interest in the effects of diet on health. Nutrition, therefore, becomes an unusually accessible entry point into public health education and intervention programs. Because food intake is determined not only by individual choice but also by cultural and social norms, economic status, and agricultural and food policies, public health approaches to dietary intervention are not only appropriate, but necessary.
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This chapter discusses diet and nutrition within the broad context of public health. It describes the health impact of dietary intake below and above recommended levels of energy and essential nutrients. It reviews current standards and guidelines for patterns of food intake that best meet nutritional requirements, improve nutritional status, and promote health. Finally, it suggests public health strategies to address behavioral and environmental barriers to consumption of healthful diets by individuals and populations.
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DIETARY REQUIREMENTS AND ALLOWANCES
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People require a continuous supply of external food sources of energy and essential nutrients to maintain life, grow, and reproduce.1,2 By definition, essential nutrients are those that cannot be synthesized in adequate amounts by the body; their dietary or metabolically induced deficiency causes recognizable symptoms that disappear when they are replaced. The list of nutrients essential or otherwise useful to human physiology is long, complex, and almost certainly incomplete. It includes the more than 40 distinct substances listed in Table 72-1: sources of energy, amino acids, fatty acids, vitamins, minerals and trace elements, fiber, and water. As indicated in Table 72-1, other nutrients also may be required under certain conditions.
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