i Estimation of polyphenol intake and the association with cognitive performance in UK women Hanis Mastura Yahya Submitted in accordance with the requirements for the degree of Doctor of Philosophy The University of Leeds School of Food Science and Nutrition Institute of Psychological Sciences November 2013 ii The candidate confirms that the work submitted is her own and that appropriate credit has been given where reference has been made to the work of others. This copy has been supplied on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgment. © 2013 The University of Leeds and Hanis Mastura Yahya iii Acknowledgements I view the journey to complete my PhD degree as a colourful experience that has taught me about myself. Above all, I would never have been able to complete my thesis without blessings and guidance from Allah. My deepest gratitude goes to all my supervisors who without them my PhD journey would have been much more difficult. Firstly, I offer my deepest appreciation to Professor Gary Williamson for the opportunity he gave to work under his supervision. His mentorship was paramount in providing me with excellent guidance, patience, and detailed and constructive comments which are crucial for my long-term development. To Prof Louise Dye for the patient guidance, persistent support and encouragement which really helped me to have the confidence to carry out my study in the field that I have always been passionate about – Psychology. Finally, to Dr Andrea Day, for her unlimited advice, encouragement and sharing that lifted up my spirit and enthusiasm throughout the ups and downs of the journey. The joint supervision of all my supervisors was a very meaningful experience that I will always remember. My appreciation extends to my fellow friends in the Food Biochemistry group: Fadhilah, Heidi, Jeab, Sam, Joana, Kerstin, Kayleigh, Chiara, Ebru, Rui, Nicolai, Damon, Reyna, Yuanlu, and Abdurrahman who kept me company in the lab and provided invaluable suggestions and motivation throughout the course of the study. The completion of this thesis would have been much more difficult without your friendship, support and encouragement. These thanks are also extended to the fellow friends and staff I have made in the School of Food Science and Nutrition during my time here. iv My sincere thanks also go to Fiona, Iria, Amy, Faye, Emily and all my colleagues in the HARU for their help and advice, and with whom it was a pleasure to work alongside. Special thanks to all volunteers as without their willingness and commitment, the polyphenol food intake and cognitive performance study would not have been possible. This project would not be possible without the tireless support from the volunteers. Above all, my deepest appreciation to my parents, Yahya Mansor and Azizah Ismail, my siblings Hafiz, Nizam and his wife; Siti Sohana, my nieces, Nabila and Nadiah, and the rest of Yahya’s family for countless reasons. Thank you for the endless emotional support and prayers throughout the years. I would like express appreciation to my beloved husband, Khusairi for his supports throughout the years. Not forgotten, a very special thanks to my extended families and friends (Khalisah, Mafuzah, Syazwani, Wani, Lily, Raja, Ain, Nassya, Fairuz, Fatimah, Erra, Izan, Khai, Lai Moon and the Wardah’s) for the moral support and sacrifices they have made in many during the many years of my pursuit of knowledge. Finally, the support from Ministry of Higher Education of Malaysia and Universiti Kebangsaan Malaysia is also greatly appreciated. I thank them for awarding me the scholarship that made this work possible. v Abstract Interest in estimating polyphenol intake and identification of the major dietary sources of polyphenols have risen in tandem with the reporting of certain health benefits of polyphenols, but only a few studies have reported polyphenol intake in the UK population. This thesis, therefore, aims to address this research gap amongst a sample of 246 UK women aged 18-50 years. A food diary was used to estimate food intake, and only ingredients with a polyphenol content of ≥ 1 mg per portion of food were included for estimation of polyphenol intake. Missing data for polyphenol content in some foods was determined by using the Folin-Ciocalteu assay and performing HPLC analysis. The polyphenol intake of the studied population was 1089 ± 814 mg/day. Tea and coffee were the major polyphenol sources while fruit, vegetables and confectionaries were other important sources of polyphenols. Age was the main predictor of flavonoid, phenolic acid and total polyphenol intake, with the increasing age associated with higher consumption. Cognitive performance was assessed using selected cognitive tests in a sub sample of the participants (Diet and Health study). Participants at the lowest quartile of polyphenol intake and who were non-consumers of coffee or tea were younger and have showed better performance on spatial memory assessed from Visual Spatial Learning Test (VSLT) (p<0.01). Age was an important predictor for both polyphenol intake and cognitive performance and partly explains the minor contribution of polyphenol intake to the cognitive performance of the studied population. This study has contributed to the understanding of the relationship between polyphenol intake and cognitive performance. vi List of Abbreviations % Percent C Degree Celsius µl Microlitre µM Micromolar µmol Micromol BMI Body mass index (kg/m2) Corsi Corsi Block Tapping Test CY3RUT Cyanidin-3-O-rutinoside DH Diet and Health study DINE Dietary Instrument for Nutrition Education DP3RUT Delphinidin-3-O-rutinoside g Gram GAE Gallic acid equivalent HPLC High performance liquid chromatography Kcal Kilocalorie kg Kilogram LWW Leeds Women’s Well-being study LWW DINE Leeds Women’s Wellbeing DINE LWW HF Leeds Women’s Well-being High Fibre study mg Milligram ml Millilitre NART National Adult Reading test ns Not significant RNI Reference Nutrient Intake USDA United States Department of Agriculture s.d Standard deviation TOH Tower of Hanoi VSLT Visual Spatial Learning Test VVLT Visual Verbal Learning Test WAIS Wechsler Adult Intelligence Scale vii Publications 1. List of publication in progress (to be submitted): (1) The association between habitual polyphenol intake and cognitive performance in women [International Journal of Food Science and Nutrition]. (2) Estimated polyphenol intake of UK women [European Journal of Nutrition]. (3) Estimated polyphenol intake in adults – a review [Food and Function]. 2. Posters: (1) Hanis Mastura Yahya, Andrea Day, Louise Dye, Clare Lawton, Fiona Croden, Gary Williamson. Estimated daily polyphenol intake among overweight women: a preliminary study. 5th International Conference on Polyphenols and Health (ICPH), 17 to 20 October 2011, Sitges, Barcelona, Spain. viii Table of Contents Acknowledgements .............................................................................................................................. iii Abstract.................................................................................................................................................. v List of Abbreviations ........................................................................................................................... vi Publications ......................................................................................................................................... vii Table of Contents ............................................................................................................................... viii Appendix list ........................................................................................................................................ xii List of Figures ...................................................................................................................................... xv List of Tables ....................................................................................................................................... xx Chapter 1 Dietary Polyphenol Intake and Cognitive Function ......................................................... 1 1.1 Abstract ............................................................................................................................ 1 1.2 Polyphenol sub-classes ..................................................................................................... 2 1.2.1 Flavonoids .......................................................................................................... 4 1.2.2 Phenolic acids ..................................................................................................... 5 1.2.3 Other polyphenols .............................................................................................. 6 1.3 Determination of polyphenol intake ................................................................................. 8 1.3.1 Measurement of food intake ............................................................................... 8 1.3.2 Estimation of polyphenol content from database ............................................. 10 1.4 Polyphenol intake estimation in population studies ....................................................... 11 1.5 Major contributors to polyphenol intake ........................................................................ 17 1.5.1 Tea and coffee .................................................................................................