Reports listing the trans fatty acid level in selected food items are available from the United States (Enig et al., 1990; Litin and Sacks, 1993; Michels and Sacks, 1995), Canada (Ratnayake et al., 1993), and Europe (Aro et al., 1998a, 1998b, 1998c; Michels and Sacks, 1995; van Erp-baart et al., 1998; van Poppel et al., 1998). More recently, a comprehensive U.S. database was compiled by the U.S. Department of Agriculture (ARS, 2001) that included a description of the methodology used to formulate the nutrient values (Schakel et al., 1997). Trans fatty acids are present in foods containing traditional stick margarine (3.04 g trans fatty acids/serving) and vegetable shortenings (2.54 g/serving) that have been subjected to hydrogenation, as well as in milk (0.22 g/serving), butter (0.40 g/serving) and meats (0.01 to 0.21 g/serving) (Emken, 1995). Therefore, foods that are contributors of trans fatty acids include pastries, fried foods (e.g., doughnuts and french fries), dairy products, and meats. Human milk contains approximately 1 to 5 percent of total energy as trans fatty acids (Table 8-7) and similarly, infant formulas contain approximately 1 to 3 percent (Ratnayake et al., 1997).

Estimating the amount of trans fatty acids in the food supply has been hampered by the lack of an accurate and comprehensive database from which to derive the data and the trend towards the reformulation of products over the past decade to reduce levels. This latter issue complicates analysis of historical food intake data. Additionally, the variability in the trans fatty acid content of foods within a food category is extensive and can introduce substantial error when the calculations are based on food frequency questionnaires that heavily rely on the grouping of similar foods (Innis et al., 1999). trans Fatty acid intake is not currently collected in U.S. national surveys.

Early reports suggested a wide range of trans fatty acid intakes, from 2.6 to 12.8 g/d (Emken, 1995). The lower estimated intakes tended to be derived from food frequency data, whereas the higher estimated intakes tended to be derived from food availability data. More recent data from food frequency questionnaires collected in the United States suggest average trans fatty acid intakes of 1.5 to 2.2 percent of energy (Ascherio et al., 1994; Hu et al., 1997), or 5.2 percent of total dietary fat (Lemaitre et al., 1998). Intakes of about 1 to 2 percent of energy have been reported for women in Canada, although the range of intakes was wide (Elias and Innis,

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)