The effects of apples and apple juice on acute plasma uric acid production and satiety: a randomised controlled trial Sara Jayne White A thesis submitted in partial fulfilment of the requirements for the degree of Master of Dietetics At the University of Otago, Dunedin, New Zealand June 2015 ! ! "! ! Abstract Background: It has been suggested that fructose from natural sources including fruit and fruit juice behaves differently in the body than added fructose from processed foods. Furthermore, there is inconclusive evidence regarding whether whole fruit and fruit juice differ in their ability to satiate, and their effects on appetite post consumption. Methods: We conducted a randomised controlled crossover trial, with 64 healthy young adults. The three arms of the study included the consumption of whole Royal Gala apples, 100 % New Zealand apple juice, or a control beverage of glucose or fructose in solution. Mean change in acute uric acid concentration and incremental area under the curve were measured at baseline, and then 30 and 60 minutes post food consumption. Satiety ratings from apple and apple juice were measured using visual analogue scales at baseline, 30 and 60 minutes post consumption. Results: We observed a significant difference in plasma uric acid concentration for all three foods at 30-60 minutes, except the glucose monosaccharide beverage. No significant difference existed between the uric acid increase from apples (P=0.286) or apple juice (P=0.132) and the fructose beverage. However, the apple juice and fructose beverages displayed a greater rate of increase than whole apples. Some measures of appetite were significantly different between the solid and liquid foods during the first 30 minutes, with whole apple more satiating than apple juice. Conclusions: Fructose control, whole apple and apple juice displayed the same plasma uric acid raising potential. These findings suggest the body treats fructose as fructose, independent of the food source. Whole apples were more satiating than apple juice, providing evidence for the consumption of whole fruit to be encouraged over fruit juice. ! Key words: fructose, uric acid, satiety, apples, apple juice, fruit, intrinsic, natural. ii Preface The candidate developed the research protocols together with her supervisor Dr Bernard Venn, co-supervisor Ph.D. candidate Mr Andrew Reynolds and Master of Dietetics candidate Emma Carran. The effect of fructose from apples, commercially available apple juice and control beverages on plasma uric acid concentration and satiety are presented in this thesis. These data are a component of a larger set, which includes acute plasma uric acid response to sugar-sweetened beverages, changes to blood pressure, and gastrointestinal symptoms experienced on consumption of the intervention foods. Genotyping will be undertaken on DNA collected during the study, which is not a component of this thesis. Master of Dietetics candidate Emma Carran will present data from a commercially available, sugar-sweetened beverage separately. In partnership with Emma Carran, the candidate shared the responsibility of recruitment, dietary instruction, procurement of test foods, food preparation, participant attendance, data collection and laboratory analysis. The candidate was primarily responsible for the design of the satiety and gastrointestinal questionnaires, for data entry, and collating the results. In order to standardise portion size, the fructose content and sugar profiles of the test foods (Royal Gala apples, and commercial 100 % apple juice) were analysed by Cawthron Institute Laboratories Ltd, Nelson, New Zealand. All other analyses were carried out by the candidates in the Department of Human Nutrition, University of Otago, Dunedin, New Zealand. ! iii Acknowledgements Firstly to my supervisor Dr Bernard Venn, thank you for your guidance and wisdom, and for giving us the opportunity to conduct a randomised controlled trial. To Ph.D. candidate Andrew Reynolds for your dedication, you went beyond your obligations to this project. Our research experience would not have been the same without your input. To Emma Carran your work ethic and determination inspires me, thank you for your organisational skills and support. You kept everything in perspective. To Keiran Columb and Ivy Salih, for aiding us during the design phase and data collection phases of our trial. Your experience was indispensable. To the other staff who aided us during data collection (Angel and Marlene), thank you for coming on board and helping us despite the early morning starts. To our participants, thank you for your dedication to attending the test sessions, we could not have conducted this project without you. To the laboratory staff Ashley Duncan and Michelle Harper, thank you for your patience and guidance throughout the analysis phase. We appreciated your encouraging words throughout the semester. Dr Jill Haszard, what would we do without your statistical guidance? Your enthusiasm for statistics and our results was infectious. Thank you for the hours you spent on this project. To Mum, Dad and Nana, thank you for your support, both emotional and financial throughout this process. It has been a long five years. It was your genes that allowed me to persevere and succeed throughout my time at university. Thanks to my flatmates for your great cooking, and to Kurt for your constant support. Finally, to the ‘Sisterhood’, I would not trade you for anything. Our days spent in the office together will be some of my fondest memories from university. I look forward to working with you in the future. iv Table of contents The effects of apples and apple juice on acute plasma uric acid production and satiety: a randomised controlled trial .......................................................................................................... i Abstract ....................................................................................................................................... ii Preface ...................................................................................................................................... iii Acknowledgements ................................................................................................................... iv Table of contents ........................................................................................................................ v Appendices ............................................................................................................................. viii List of tables .............................................................................................................................. ix List of figures .............................................................................................................................. x Abbreviations ............................................................................................................................. xi 1 Introduction ........................................................................................................................ 12 2 Literature Review ............................................................................................................... 15 2.1 Methodology of literature review ................................................................................ 15 2.2 Introduction ................................................................................................................. 15 2.3 Fructose structure ........................................................................................................ 16 2.4 Fructose Absorption .................................................................................................... 17 2.4.1 Absorption in the small intestine .......................................................................... 17 2.5 Fructose Metabolism ................................................................................................... 17 2.6 Uric acid production .................................................................................................... 19 2.7 Sources of fructose ...................................................................................................... 20 2.7.1 Intrinsic ................................................................................................................. 20 2.7.2 Fruit juices ............................................................................................................ 21 2.7.3 Added sugars ........................................................................................................ 22 2.7.4 High fructose corn syrup ...................................................................................... 22 2.7.5 Sugar sweetened beverages .................................................................................. 22 2.8 Sugars and fructose consumption in New Zealand ..................................................... 22 2.9 Fructose and health ...................................................................................................... 23 2.9.1 Perceived health benefits of fructose ................................................................... 23 2.9.2 Fructose health claim ........................................................................................... 24 2.10 Diseases associated with excess fructose consumption .............................................. 24 2.10.1 Gout .................................................................................................................... 24 2.10.2 Obesity ............................................................................................................... 26 2.11 Satiety and fructose ..................................................................................................... 26 2.11.1 Solid versus liquid foods and satiety .................................................................. 26 v 2.12 Rationale for our research ........................................................................................... 27 3 Objective statement ............................................................................................................ 28 4 Methods .............................................................................................................................. 29 4.1 Ethical approval ........................................................................................................... 29 4.2 Enrollement and participation requirements ............................................................... 29 4.3 Randomisation ............................................................................................................. 30 4.4 Intervention foods ....................................................................................................... 32 4.5 Control foods ............................................................................................................... 32 4.6 Sugar composition analysis ......................................................................................... 32 4.7 Amounts administered ................................................................................................. 33 4.8 Intervention ................................................................................................................. 34 4.8.1 Outcome measures ............................................................................................... 37 4.8.2 Laboratory procedures .......................................................................................... 38 4.8.3 Study outcomes .................................................................................................... 40 4.8.4 Raw data handling ................................................................................................ 40 4.9 Statistical methods ....................................................................................................... 40 4.9.1 Sample size calculation ........................................................................................ 40 4.9.2 Outliers ................................................................................................................. 41 4.9.3 Analysis ................................................................................................................ 41 4.9.4 Plasma uric acid ................................................................................................... 41 4.9.5 Satiety ................................................................................................................... 42 5 Results ................................................................................................................................ 43 5.1 Baseline characteristics of participants ....................................................................... 43 5.2 Acute plasma uric acid response ................................................................................. 44 5.3 Incremental area under the curve ................................................................................ 47 5.4 Satiety .......................................................................................................................... 48 6 Discussion ........................................................................................................................... 52 6.1 Satiation ....................................................................................................................... 55 6.2 Strength and limitations .............................................................................................. 56 6.3 Conclusions and recommendations ............................................................................. 58 7 Implications to dietetic practice .......................................................................................... 59 8 Literature Cited ................................................................................................................... 61 Appendices ............................................................................................................................... 72 Appendix A ............................................................................................................................... 73 Appendix B ............................................................................................................................... 89 Appendix C ............................................................................................................................... 94 vi Appendix D ............................................................................................................................... 99 8.1 Communication strategy: .......................................................................................... 100 Appendix E ............................................................................................................................. 101 8.2 Blood Collection protocol ......................................................................................... 102 Appendix F ............................................................................................................................. 103 Appendix G ............................................................................................................................. 105 Appendix H ............................................................................................................................. 108 8.3 Dilution curve ............................................................................................................ 109 vii Appendices A. Ethics Application related documents: ! Ethics application form ! Participant information sheet ! Participant consent form ! M!ori Consultation ! Demographic questionnaire B. Ethical approval ! Amendment letter ! Ethical approval letter ! M!ori consultation letter of approval C. Food composition analysis ! Cawthron Laboratory certificate of analysis ! Reference for laboratory protocol D. Communication strategy E. Blood collection protocol F. Second test session adherence questionnaire G. Satiety questionnaires H. Dilution curve ! #"""! List of tables Table 1 Sugar composition of some common fructose containing foods (g/100g (19, 63) ..... 21! Table 2. Results from Cawthron Laboratories Ltd sugar assessment, February 2015 ............. 33! Table 3. Large servings of intervention foods containing 26.7 grams of fructose and small ... 34! Table 4. Demographics of study participants ........................................................................... 44! Table 5. Adjusted * mean difference in plasma uric acid concentration between baseline and 30 minutes, and 30 and 60 minutes of both large and small servings of all test foods ............ 45! Table 6. Adjusted* difference in iAUC of small and large servings of test foods and beverages .................................................................................................................................................. 47! Table 7. Adjusted* difference in iAUC between large servings of apples and apple juice, compared with the fructose control .......................................................................................... 48! Table 8a. mean differences between small servings of whole apples and apple juice groups of questions measuring satiety ...................................................................................................... 49! Table 8b. mean differences between large servings of whole apples and apple juice groups of questions measuring satiety ...................................................................................................... 50! ix ! List of figures Figure 1. structure of D-fructose in linear form (45) ................................................................ 16! Figure 2. Pathways of fructose metabolism in the muscle (left), and in the liver (right) (45) . 18! Figure 3. The relationship between fructose metabolism and the formation of uric acid in the liver. .......................................................................................................................................... 20! Figure 4. monosaccharides glucose and fructose bonded through a 1-2 glucosidic bond to form sucrose (45). ..................................................................................................................... 21! Figure 5. Consort Diagram: Flow of participants through the study, in control, apple juice and apple groups. ............................................................................................................................. 31 Figure 6. Study design: Participants were randomly allocated to apple, apple juice or control groups, and an attendance week (weeks one and three or two and four)……………………. 36 Figure 7. Visual comparison of the adjusted mean difference (µmol/L!h) between large servings of apple (410 g) and apple juice (370 mL) and fructose control between baseline and 30 minutes, and 30 and 60 minutes. ......................................................................................... 46! Figure 8. The correlation between uric acid concentration and the percentage of control Path was determined to be lineraly distributed. .............................................................................. 109! x