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INTRODUCTION 1 INTRODUCTION F or more than half a century, the Recommended Dietary Allowances (RDAs) of the United States and the Dietary Standards/Recommended Nutrient Intakes (RNIs) of Canada have served as the chief components for nutri- tion policy in their respective countries, playing dominant roles in the task of meeting the known nutritional needs of healthy people in North America. Revised and updated many times throughout their history, the RDAs and RNIs generally reflected changes resulting from the broader evolution taking place in the field of nutrition science. However, by the 1990s, a number of important developments had occurred that dramatically altered the nutrition research landscape and ultimately challenged the RDA and RNI status quo. Among them were the significant gains made in scientific knowledge regarding the link between diet, health, and chronic disease, and the emergence of ad- vanced technologies that could measure small changes in individual adapta- tions to various nutrient intakes. Additionally, the use of fortified or enriched foods and the increased consumption of nutrients in pure form, either singly or in combination with others outside of the context of food, prompted the closer examination of the potential effects of excess nutrient intake. In 1994, in response to these and other important considerations, the Food and Nutrition Board of the National Academies’ Institute of Medicine, with support from the U.S. and Canadian governments and others, embarked on an initiative to develop a new, broader set of dietary reference values, known as the Dietary Reference Intakes (DRIs). The DRIs expand upon and replace the RDAs and RNIs with four categories of values intended to help individuals optimize their health, prevent disease, and avoid consuming too much of a nutrient. These dietary reference values were subsequently published in a series of re- ports released between 1997 and 2005, titled the Dietary Reference Intakes. Recognizing the groundbreaking nature of the series and its impact on the nutrition community, the Food and Nutrition Board and Health Canada came together again in 2005 in an effort to extend the reach of the original reports to a wider audience. Dietary Reference Intakes: The Essential Guide to Nutrient Re- quirements is the result of their collaboration. Based on the key concepts and recommendations set forth in the original DRI series, this book serves as a prac- tical, hands-on reference to help guide health professionals in the United States and Canada in their day-to-day task of assessing and planning for the nutrient needs of individuals and groups of people. This book also provides educators
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DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 2 with a tool for guiding students in the understanding of the DRI concept and use of the reference values. The book is divided into four parts: Part I provides a foundation for under- standing how and why the DRIs were developed, definitions of the DRI catego- ries, and specific guidance on their appropriate uses. Part II presents discus- sions on reference values for dietary carbohydrate, fiber, total fat, fatty acids, cholesterol, protein, amino acids, and water. Major new approaches and find- ings included in this section are formulas for estimating energy requirements; recommended physical activity levels; the definition of dietary fiber; and Ac- ceptable Macronutrient Distribution Ranges (AMDRs), which have been intro- duced as a percentage of energy intake for fat, carbohydrate, protein, and li- noleic and a-linolenic acids. Also included is information on the relationship between macronutrients and chronic disease. Part III profiles 35 individual nutrients. In addition to providing reference values, each profile reviews the function of a given nutrient in the human body; summarizes the known effects of deficiencies and excessive intakes; describes how a nutrient may be related to chronic disease or developmental abnormali- ties; and provides the indicator of adequacy for determining the nutrient re- quirements. A comprehensive set of appendixes, including a glossary and summary tables of DRI values appear in Part IV. Full references, which also appear in the parent report series, the Dietary Reference Intakes, are provided online at http:// www.nap.edu/catalog/11537.html.