Humans lack digestive enzymes to cleave β-(1,4) linkages and thus cannot absorb glucose from cellulose. Powdered cellulose is a purified, mechanically disintegrated cellulose obtained as a pulp from wood or cotton and is added to food as an anticaking, thickening, and texturizing agent. Dietary cellulose can be classified as Dietary Fiber or Functional Fiber, depending on whether it is naturally occurring in food (Dietary Fiber) or added to foods (Functional Fiber).

Chitin and Chitosan. Chitin is an amino-polysaccharide containing β-(1,4) linkages as is present in cellulose. Chitosan is the deacetylated product of chitin. Both chitin and chitosan are found in the exoskeletons of arthropods (e.g., crabs and lobsters) and in the cell walls of most fungi. Neither chitin nor chitosan is digested by mammalian digestive enzymes. Chitin and chitosan are primarily consumed as a supplement and potentially can be classified as Functional Fibers if sufficient data on physiological benefits in humans are documented.

β-Glucans. β-glucans are homopolysaccharides of branched glucose resides. These β-linked D-glucopyranose polymers are constituents of fungi, algae, and higher plants (e.g., barley and oats). Naturally occurring β-glucans can be classified as Dietary Fibers, whereas added or isolated β-glucans are potential Functional Fibers.

Gums. Gums consist of a diverse group of polysaccharides usually isolated from seeds and have a viscous feature. Guar gum is produced by the milling of the endosperm of the guar seed. The major polysaccharide in guar gum is galactomannan. Galactomannans are highly viscous and are therefore used as food ingredients for their thickening, gelling, and stabilizing properties. Gums in the diet can be classified as Dietary or Functional Fibers.

Hemicelluloses. Hemicelluloses are a group of polysaccharides found in plant cell walls that surround cellulose. These polymers can be linear or branched and consist of glucose, arabinose, mannose, xylose, and galacturonic acid. Dietary hemicelluoses are classified as Dietary Fibers.

Inulin, Oligofructose, and Fructooligosaccharides. Inulin and oligofructose are naturally occurring in a variety of plants. Most of the commercially available inulin and oligofructose is either synthesized from sucrose or extracted and purified from chicory roots. Oligofructose is also formed by partial hydrolysis of inulin. Inulin is a polydisperse β-(2,1)-linked fructan with a glucose molecule at the end of each fructose chain. The chain length is usually 2 to 60 units, with an average degree of polymerization of

Front Matter (R1-R26)

Summary (1-20)

1. Introduction to Dietary Reference Intakes (21-37)

2. Methods and Approaches Used (38-52)

3. Relationship of Macronutrients and Physical Activity to Chronic Disease (53-83)

4. A Model for the Development of Tolerable Upper Intake Levels (84-106)

5. Energy (107-264)

6. Dietary Carbohydrates: Sugars and Starches (265-338)

7. Dietary, Functional, and Total Fiber (339-421)

8. Dietary Fats: Total Fat and Fatty Acids (422-541)

9. Cholesterol (542-588)

10. Protein and Amino Acids (589-768)

11. Macronutrients and Healthful Diets (769-879)

12. Physical Activity (880-935)

13. Applications of Dietary Reference Intakes for Macronutrients (936-967)

14. A Research Agenda (968-971)

Appendix A: Glossary and Acronyms (972-977)

Appendix B: Origin and Framework of the Development of Dietary Reference Intakes (978-984)

Appendix C: Acknowledgments (985-987)

Appendix D: Dietary Intake Data from the Third National Health and Nutrition Examination Survey (NHANES III), 1988-1994 (988-1027)

Appendix E: Dietary Intake Data from the Continuing Survey of Food Intakes by Individuals (CSFII) 1994-1996, 1998 (1028-1065)

Appendix F: Canadian Dietary Intake Data, 1990-1997 (1066-1075)

Appendix G: Special Analyses for Dietary Fats (1076-1077)

Appendix H: Body Composition Data Based on the Third National Health and Nutrition Examination Survey (NHANES III), 1988-1994 (1078-1103)

Appendix I: Doubly Labeled Water Data Used to Predict Energy Expenditure (1104-1202)

Appendix J: Association of Added Sugar Intake and Intake of Other Nutrients (1203-1225)

Appendix K: Data Comparing Carbohydrate Intake to Intake of Other Nutrients from the Continuing Survey of Food Intakes by Individuals (CSFII), 1994-1996, 1998 (1226-1243)

Appendix L: Options for Dealing with Uncertainties (1244-1249)

Appendix M: Nitrogen Balance Studies Used to Estimate the Protein Requirements in Adults (1250-1258)

Biographical Sketches of Panel and Subcommittee Members (1259-1274)

Index (1275-1318)

Summary Tables, Dietary Reference Intakes (1319-1331)