Loma Linda University TheScholarsRepository@LLU: Digital Archive of Research, Scholarship & Creative Works Loma Linda University Electronic Theses, Dissertations & Projects 6-2014 Vegetarian Dietary Patterns: Mortality, Colorectal Cancer, and Food Consumption Michael John Orlich Follow this and additional works at: http://scholarsrepository.llu.edu/etd Part of the Diseases Commons, and the Epidemiology Commons Recommended Citation Orlich, Michael John, "Vegetarian Dietary Patterns: Mortality, Colorectal Cancer, and Food Consumption" (2014). Loma Linda University Electronic Theses, Dissertations & Projects. 184. http://scholarsrepository.llu.edu/etd/184 This Dissertation is brought to you for free and open access by TheScholarsRepository@LLU: Digital Archive of Research, Scholarship & Creative Works. It has been accepted for inclusion in Loma Linda University Electronic Theses, Dissertations & Projects by an authorized administrator of TheScholarsRepository@LLU: Digital Archive of Research, Scholarship & Creative Works. For more information, please contact [email protected]. LOMA LINDA UNIVERSITY School of Public Health in conjunction with the Faculty of Graduate Studies ________________________________ Vegetarian Dietary Patterns: Mortality, Colorectal Cancer, and Food Consumption By Michael John Orlich ________________________________ A Dissertation in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Epidemiology ________________________________ June 2014 © 2014 Michael John Orlich All rights Reserved Each person whose signature appears below certifies that this dissertation in his/her opinion is adequate, in scope and quality, as a dissertation for the degree Doctor of Philosophy. , Chairperson Gary E. Fraser, Professor of Epidemiology Joan Sabaté, Professor of Nutrition and Epidemiology Pramil N. Singh, Associate Professor of Epidemiology and Global Health iii CONTENT Approval Page .................................................................................................................... iii List of Tables .................................................................................................................... vii List of Figures .................................................................................................................... ix Abstract ............................................................................................................................... x Chapter 1. Introduction ............................................................................................................ 1 The Challenge of Nutritional Epidemiology............................................... 1 Dietary Patterns ........................................................................................... 2 Vegetarian Dietary Patterns ........................................................................ 2 Specific Aims .............................................................................................. 3 2. Literature Review .................................................................................................. 4 Studies of Vegetarians ................................................................................ 4 Characterization of Vegetarian Diets .......................................................... 9 Vegetarian Diets and Mortality ................................................................. 13 Vegetarian Diets and Colorectal Cancer ................................................... 19 Risk Factors and Intermediates ................................................................. 24 Summary ................................................................................................... 25 3. Patterns of Food Consumption Among Vegetarians and Nonvegetarians .......... 27 Abstract ..................................................................................................... 28 Introduction ............................................................................................... 29 Methods..................................................................................................... 30 Study Population ................................................................................. 30 Dietary Data ........................................................................................ 30 Dietary Pattern Definitions ................................................................. 32 Categorization of Foods ...................................................................... 32 Covariates ........................................................................................... 33 Statistical Analysis .............................................................................. 33 Results ....................................................................................................... 35 Food Consumption for the Entire Sample .......................................... 35 iv Food Consumption by Dietary Pattern: Major Food Groups.............. 40 Food Consumption by Dietary Pattern: Minor Food Groups ............ 42 Discussion ................................................................................................. 47 Acknowledgments..................................................................................... 53 References ................................................................................................. 54 4. Vegetarian Dietary Patterns and Mortality in Adventist Health Study 2 ............ 62 Abstract ..................................................................................................... 64 Background ............................................................................................... 66 Methods..................................................................................................... 67 Study Population ................................................................................. 67 Mortality Data ..................................................................................... 68 Dietary Data ........................................................................................ 68 Covariates ........................................................................................... 69 Statistical Analysis .............................................................................. 72 Results ....................................................................................................... 73 Baseline Characteristics ...................................................................... 73 Mortality ............................................................................................. 75 Comment ................................................................................................... 81 Acknowledgements ................................................................................... 86 References ................................................................................................. 88 5. Vegetarian Dietary Patterns and the Risk of Colorectal Cancers ........................ 92 Abstract ..................................................................................................... 93 Introduction ............................................................................................... 95 Methods..................................................................................................... 96 Study Population ................................................................................. 96 Outcome Data ..................................................................................... 97 Dietary Data ........................................................................................ 98 Covariate Data .................................................................................... 99 Statistical Analysis .............................................................................. 99 Results ..................................................................................................... 101 Discussion ............................................................................................... 111 References ............................................................................................... 115 6. Conclusion ......................................................................................................... 119 Summary ................................................................................................. 119 v Limitations .............................................................................................. 121 Importance and Implications................................................................... 123 Future Work ............................................................................................ 130 Concluding Remarks ............................................................................... 135 References ....................................................................................................................... 139 Appendix A ..................................................................................................................... 147 Vegetarian Diets in the Adventist Health Study 2: A Review of Initial Published Findings......................................................................................................... 147 Abstract ................................................................................................... 148 Introduction