significant increase in stool weight, however, was observed when men consumed 32 g/d RS₃ for 4 weeks (Heijnen et al., 1998). Jenkins and coworkers (1998) determined the effects of low fiber (control), wheat bran supplements providing an additional 30 g of fiber (high fiber control), or the equivalent amount of resistant starch as RS₂ or RS₃. Compared to the low fiber control, the wheat bran supplement increased fecal bulk by 96 ± 14 g/d (p < 0.001) and the mean for both resistant starches was 22 ± 8 g/d greater than controls (p = 0.013). This is consistent with the small increase in fecal bulk seen with resistant starch intake in other studies (Behall and Howe, 1996; Cummings et al., 1996; Heijnen et al., 1998; Hylla et al., 1998; Phillips et al., 1995).

Because resistant starch is partly fermented in the colon, intake may lead to increased production of short-chain fatty acids. When 39 g/d of a mixture of naturally occurring and processed resistant starch was consumed, there was a significant increase in fecal butyrate and acetate concentrations, and therefore a significant reduction in fecal pH (Phillips et al., 1995). However, when glucose or 32 g/d of RS₃ was consumed for 4 weeks, there was no difference in fecal pH, fecal short-chain fatty acid concentrations, or fecal secondary bile acid concentrations (Heijnen et al., 1998).

Normalization of Blood Lipid Concentrations. Several animal studies have demonstrated a lowering of blood cholesterol and triacylglycerol concentrations with resistant starch intake (de Deckere et al., 1993; Ranhotra et al., 1997; Younes et al., 1995). When healthy, normolipidemic individuals were given glucose or 30 g/d of RS₃ supplements for 3 weeks, there were no significant differences in fasting serum total, LDL, and HDL cholesterol concentrations or triacylglycerol concentrations (Heijnen et al., 1996). Resistant starch does not appear to provide the cholesterol-lowering effects of viscous fiber, but rather acts more like nonviscous fiber (Jenkins et al., 1998). Neither Jenkins and coworkers (1998) nor Heijnen and coworkers (1996) showed a lowering effect of resistant starch on serum lipids.

Attenuation of Blood Glucose Responses. Adding resistant starch to bread at various levels (0, 5, 10, and 20 percent) was shown to reduce the glycemic index in a dose-dependent manner (100, 96, 74, and 53) (Brown et al., 1995). The consumption of 30 g/d of RS₃ was shown to significantly reduce the urinary excretion of C-peptide, indicating reduced insulin secretion (de Roos et al., 1995).

Dietary and Functional Fibers are not essential nutrients, so inadequate intakes do not result in biochemical or clinical symptoms of a deficiency. A

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)