Copyright is owned by the Author of the thesis. Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the permission of the Author. The role of dietary patterns, inflammatory status and gut microbiome in bone health maintenance of postmenopausal women – A cross-sectional study A thesis presented in fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science School of Health Sciences Massey University, Palmerston North Bolaji Lilian Ilesanmi-Oyelere 2020 ii To my loving husband Peter and our blessings Dafidi III & Maria II iii Abstract The incidence of postmenopausal osteoporosis (a disease in which bones become weak and brittle) is increasing in parallel with the ageing of the global population. Postmenopausal osteoporosis is characterized by increased low grade inflammation that contributes to low bone mass and degradation of bone mineral density (BMD) resulting in postmenopausal bone loss. Elevated levels of pro-inflammatory cytokines such as IL-6, TNF-α, IL-1β and RANKL are produced by activated T-cells inducing osteoclast formation and activity during senescence. The objective of the “Bugs’n’Bones” clinical study was to assess the relationship between dietary patterns, inflammatory status, gut microbiota and bone health status in New Zealand postmenopausal women. We hypothesised that lack of physical activity, increased intake of poor diets, low in fibre and nutrients, and high in fat, salt and/or sugar will increase chronic inflammation and reduce BMD. The results of this human study indicated that alongside improving physical activity status with increase in lean body mass, a nutrient pattern with high loadings of B-vitamins, calcium and phosphorus was related to an increase in BMD. In addition, dietary pattern with a high factor loading of milks and milk-rich beverages was associated with a high BMD and T-score. The results of this study also indicated that a high circulatory level of inflammatory cytokines was associated with lower BMD in the postmenopausal women. The results of the gut microbiota analyses showed that microbial composition diversity (alpha diversity by Shannon index) was significantly lower amongst the osteopenic/osteoporotic groups than their healthy counterparts. The interferon gamma receptor 1 orthology group was significantly higher in abundance for the OP (osteopenic/osteoporotics) than the H (healthy) groups based on the hip and femoral neck osteoporosis status. Future longitudinal and intervention studies which aim to modulate the gut microbiota via dietary change is warranted. It is also important to conduct these interventions with prebiotics, probiotics and synbiotics in animal and human models. iv Acknowledgements First and foremost, I am grateful to the Almighty Lord God for the gift of life and for enabling me to accomplish this milestone. ‘For You, O Lord, will bless the righteous with favour; You will surround him as a shield’ – Psalm 5:12. I had like to thank my extraordinary supervisor, Prof. Marlena Kruger for your amazing support and for always being gracious and approachable. Thank you for single-handedly sourcing the funding for this work. May God’s goodness, mercy and love continue to overshadow you. I would also like to thank my affable co-supervisors, Prof. Nicole Roy (for partly funding the research) and Prof. Jane Coad for their commitment and mentorship. Thank you and may God richly bless you. I am grateful for the contributions and advice from Prof. Michelle McConnell, Dr. Elizabeth Rettedal, Dr. Linda Schollum, Dr. Barbara Kuhn-Sherlock and Dr. Louise Brough. Indeed, I am highly indebted to Riddet Institute for awarding me a scholarship for my PhD studies. I would also like to acknowledge Palmerston North Medical Research Foundation, Fonterra Cooperative Group Ltd and Allen Foundation, USA for funding this research as well as the School of Food and Advanced Technology, Massey University for financial and resource support throughout my PhD. I thank AgResearch Limited for providing resources for the gut microbiota analyses and thanks to Massey Genomics Services (MGS) and Otago Genomics and Bioinformatics Facility (OGBF) for their help with DNA prep and sequencing respectively. The technical expertise and assistance from Annie Broomfield for conducting the DXA for the ladies, Gabby Plimmer for the ELISA tests, Shampa De for the DNA extractions (Massey University), Sonya Mros and Katie Young for the cytokine analyses (Otago University) are greatly appreciated. Thank you, Mrs. Anna Willoughby, for your help with blood collection. The knowledge, expertise and help from the librarians; Chris Good, Anne Ram, Lorraine Tremain, Barbara Rainier and Jeff Phillips is greatly treasured. The prayers and words of encouragement from friends (RoAnn Smith, Sewuese Okubanjo) and family (Prof. Isaac and Dr. Doris Adeyinka, Dr. Raphael and Mrs. Evelyn Folorunsho, The Oyelere’s, The Ilesanmi’s family) are much appreciated. I am grateful to Mr. Samuel Oyelere and family for their help with my family’s travel tickets while I study. Thanks to my Riddet building office colleagues Blue, Saima and Umani for a great working environment and all Riddet Complex level 3 tea room group (Dr. Fran Wolber, Louise Shaw, Dr. Sarah Bond, Corrin Hulls, Nikhi Vijay and Giovanna). My gratitude also goes to the support from my AgResearch office colleagues from Allan Johns’ building room F17. My thank you goes out to Mrs. Nicky Rees for her counselling words. v I would also like to say a big thank you to all the participants of the “Bugs’n’Bones” clinical study. Finally, and definitely not the least, I had like to thank my dear husband Prof. Peter B. Oyelere and our beautiful children Dafidi III Oyelere and Maria II Oyelere who constantly supported and encouraged me throughout my PhD journey. Thank you all. vi Table of Contents Chapter 1 Introduction ............................................................................................................... 1 1.1 Research questions ........................................................................................................ 4 1.2 Specific objectives ........................................................................................................ 4 1.3 Hypotheses .................................................................................................................... 4 1.4 Thesis structure ............................................................................................................. 5 1.5 References ..................................................................................................................... 6 Chapter 2 Literature Review ...................................................................................................... 8 2.1 Introduction ................................................................................................................... 8 2.2 Bone .............................................................................................................................. 8 2.2.1 Types of bones ...................................................................................................... 8 2.2.2 Bone structure and cells ........................................................................................ 9 2.2.3 Bone remodelling ................................................................................................ 12 2.2.4 Bone turnover biomarkers ................................................................................... 14 2.2.5 Bone turnover: age-related transition .................................................................. 17 2.2.6 Postmenopausal osteoporosis .............................................................................. 17 2.2.7 Biochemical bone regulation ............................................................................... 18 2.2.8 Factors affecting bone density ............................................................................. 19 2.2.9 Importance of selected nutrients on bone health ................................................. 21 2.3 The Role of Dietary Patterns in the Pathogenesis of Osteoporosis ............................ 23 2.3.1 A Priori dietary patterns ...................................................................................... 24 2.3.2 A Priori dietary patterns in Children and Adolescents ....................................... 24 2.3.3 A Priori studies on bone mineral status In Adults and the Elderly ..................... 24 2.3.4 A Priori studies using biomarkers In Adults and the Elderly ............................. 26 2.3.5 A Priori studies on fractures In Adults and the Elderly ...................................... 27 2.4 A posteriori dietary patterns ....................................................................................... 28 2.4.1 A posteriori dietary pattern studies that used factor analysis for BMD/BMC .... 28 2.4.2 A posteriori dietary pattern studies using factor analysis for bone biomarkers .. 32 2.4.3 A posteriori dietary pattern studies reporting the risk of osteoporosis ............... 32 2.5 Gut microbiome as a target in the pathogenesis of osteoporosis ................................ 33 2.5.1 The Gut Microbiota ............................................................................................. 33 2.5.2 The Immune system regulated by the gut microbiota ........................................