A food-based approach to increase egg and protein intake in community dwelling British older adults aged over 55 years old Emmy van den Heuvel A thesis submitted in partial fulfilment of the requirements of Bournemouth University for the degree of Doctor of Philosophy October 2017 ii Acknowledgements The completion of this thesis would not have been possible without my supervisors Prof. Katherine Appleton and Prof. Jane Murphy. Thank you very much for your support and encouragement. Thank you Katherine, without your guidance I would probably still be lost in the details by now. I have learned so much from you, and you are a true inspiration to my current and future work. Jane, thank you for giving me your expert advice throughout my studies and write up, I really appreciate it. I also would like to thank Bournemouth University for part-funding this PhD project, and all the guidance the University and department have provided. Additionally, I would like to thank the British Egg Industry Council, for part-funding this PhD studentship, and for their support and interest in my results*. My deepest gratitude goes to all my participants, without you this project would not have been possible. I really enjoyed meeting you all, and will always be grateful for your contribution to my research. A very special thanks to the other PhD students (current and previous generations) in P104, in the psychology department, and across Bournemouth University. Thank you for your support, and for all the tea, cake, and commitments :). Thank you also for Martin Tomkins, for all your kind support; you can solve any problem. My warmest ‘dankjewel’ to all my wonderful friends and family across the sea: Inge and Marian, thank you for your continuous friendship and encouragement. Nanine, Esther, Eva, and Annemarie thank you for always believing in me. All the ‘miepen’ thank you for your inspiration and caring friendship. I also would like to thank the Rushton girls and the Rueda club in Bournemouth, for keeping me sane throughout the last years. You always make me smile, even when I was stressed. Last but not least, even in the biggest letters THANK YOU cannot cover my gratitude for Alex, mama and Lidy. Thank you for your love and support throughout the whole process. Mama, papa and Lidy, for bringing me up to the person I am today, my successes are as much yours as my own. *The British Egg Industry Council played no role in the design of the studies or the interpretation of the results. iii Copyright Statement This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and due acknowledgement must always be made of the use of any material contained in, or derived from, this thesis. iv Abstract Dietary protein has an important impact on health, physical functioning, and muscle mass, and the prevalence of protein specific under-nutrition is high among older adults. Eggs are a nutrient dense, high quality source of protein. Compared to other protein rich foods, eggs are easy to cook, of low cost, long shelf life, soft texture, and they are familiar to most people. Therefore this PhD project aimed to explore the barriers and facilitators specific to egg intake in older adults, and use these in a food-based approach to increase egg and dietary protein intake in community dwelling older adults aged over 55 years old. Focus groups were used to identify reasons for eating or not eating eggs in adults aged 55 years and older. The 69 different reasons found were then used to design a structured questionnaire. The questionnaire results reveal that the questionnaire statements (based on the reasons) can significantly predict egg consumption in a population wide sample of British older adults. The reasons significantly related to egg consumption reveal several topics to focus on when designing strategies to increase egg consumption in older adults. One of the outcomes showed that older adults who eat more eggs report thinking eggs taste good and add variety to the diet. Adding flavour and more variety may encourage intakes in those who consume fewer eggs. A randomized controlled intervention study was designed to increase egg and protein intake, by providing recipes of protein-rich egg-based meals and herb/spice packets to encourage the addition of flavour and variety to the diet. The results showed that being in the intervention group was significantly related to higher egg intake at a follow up session at the end of the study, but not directly after the intervention. Protein intake was not different between the groups at either of the time points. The current research has showed that exposing older adults to recipes and herb/spice packets can change their egg consumption, and may therefore be helpful in an easy to implement and cost effective strategy to change eating behaviour in older adults. v List of Contents Abstract ................................................................................................................... iv List of Contents ........................................................................................................ v List of Figures .......................................................................................................... x List of Tables ........................................................................................................... xi List of conference meetings attended .................................................................... xiii Author’s Declaration .............................................................................................. xiv 1. Introduction .......................................................................................................... 1 1.1 Context of the research .................................................................................. 1 1.2 Aim and objectives ......................................................................................... 3 1.2.1 Aim .......................................................................................................... 3 1.2.2 Objective 1 ............................................................................................... 5 1.2.3 Objective 2 ............................................................................................... 6 1.2.4 Objective 3 ............................................................................................... 6 2. Increasing Protein and Egg Intake in Older Adults: a Literature Review ............... 7 2.1 Dietary protein intake in older adults............................................................... 7 2.1.1 Protein specific under-nutrition in older adults .......................................... 7 2.1.2 Target age range ..................................................................................... 9 2.1.3 Current protein intake and recommendations........................................... 9 2.1.4 Distribution and dose of dietary protein intake ........................................ 12 2.1.5 Quality of different protein sources ......................................................... 13 2.1.6 Protein and satiety ................................................................................. 14 2.2 Eating behaviour in older adults ................................................................... 15 2.2.1 Anorexia of ageing ................................................................................. 15 2.2.2 Sensory abilities ..................................................................................... 16 2.2.3 Physical abilities .................................................................................... 17 2.2.4 Eating abilities ........................................................................................ 17 2.2.5 Changing eating behaviour in older adults ............................................. 18 2.2.6 Familiarity .............................................................................................. 19 2.2.7 Determinants specific to protein intake in older adults ............................ 20 2.3 Egg consumption in older adults ................................................................... 21 2.3.1 Eggs as a source of protein ................................................................... 21 2.3.2 Nutritional values of eggs ....................................................................... 21 vi 2.3.3 Eggs and satiety .................................................................................... 23 2.3.4 Eggs and Salmonella ............................................................................. 24 2.3.5 Eggs and cholesterol ............................................................................. 24 2.3.6 Eggs and diabetes ................................................................................. 25 2.3.7 General determinants of egg intake ....................................................... 25 2.4 Summary ...................................................................................................... 26 3. Exploring the reasons for eating or not eating Eggs in older Adults: a focus group study ...................................................................................................................... 28 3.1 Introduction .................................................................................................. 28 3.2 Methods ......................................................................................................