Nutrient Intake in the Kingdom of Tonga
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Nutrient Intake in the Kingdom of Tonga Associations with Overweight, Obesity and Glucose Tolerance Soana Muimuiheata Thesis submitted in fulfillment of the degree of Master of Science University of New South Wales March 2007 i ABSTRACT Diabetes mellitus, cardiovascular disease and other non-communicable diseases (NCD) have become the major cause of premature death, morbidity and disability in many Pacific countries including Tonga. Several population-based surveys have suggested that changes from a traditional to a modern way of life have enhanced the development of NCD. These diseases are multifactorial metabolic disorders where risk factors include hyperglycaemia, obesity, hypertension, lipid abnormalities, physical inactivity and poor nutrient intake. There has been little research which has specifically examined detailed food intake and nutrient composition in the Tongan population. Aims - to determine the national pattern of food and nutrient intake in Tonga and to identify associations between food and nutrient intake and overweight, obesity and glucose tolerance. Research Design and Methods – The survey was conducted in two parts, Tongatapu in 1998 and Vava‟u and Ha‟apai in 2000. A multi-stage cluster sampling design was used to select a representative sample of 1024 people age 15 years and older from the Tongan population. Information about the usual food and nutrient intake was collected by Food Frequency Questionnaire, and analysed by the Australian Food Works program. Lifestyle behaviours such as physical activity, alcohol and smoking status, the use of traditional medicine, occupation and religious practices were also collected. Anthropometric and clinical measurements – weight, height, body mass index, body fat, blood pressure, lipid profiles, fasting glucose, HbA1c, creatinine and microalbumin levels were measured. Results – The Tongan population is consuming a high carbohydrate (59% total energy intake), moderate protein (15% total energy intake) and low fat (22% total energy intake) diet, which is consistent with the WHO recommendations for a healthy diet. However the total daily energy intake is high. The mean (± SD) daily total energy intake was 4856 ± 2304 kcal and males consumed significantly more than females (5308 ±2366 vs 4522 ± 2201 kcal, p=0.009). This resulted in the diet exceeding the recommended dietary requirements for all nutrient components. There were minor differences in nutrient intake patterns in the more urban Tongatapu compared with the more rural Vava‟u/Ha‟apai. Alcohol consumption and smoking was much more ii common among men than the women and was higher in Tongatapu than Vava‟u/Ha‟apai participants. Males reported more physical activity than females. The prevalence of overweight and obesity in Tonga is very high – 93% in women and 84% in men. There has been a significant increase in prevalence of obesity among Tongans which has increased at least four-fold in men and almost doubled among women in the past 12 years. Prevalence rates were similar in rural and urban areas. Conclusion: Tonga is experiencing an increasing problem of overweight and obesity which is a major risk factor for a number of non-communicable diseases including diabetes and cardiovascular disease. A high dietary energy intake could be a contributing factor to the increasing overweight and obesity problem. The findings of this study have important implications for public health efforts and policy development to contain the epidemic of non-communicable diseases in Tonga. iii ACKNOWLEGEMENT I would like to express my sincere gratitude to my supervisor, Professor Stephen Colagiuri for his direction and guidance throughout the course of this work. His expertise, commitment and constructive criticism add value to this research. It has been a privilege to be associated with such a dedicated and enthusiastic person towards health and research. I would like to thank my co-supervisor Dr. Taniela Palu for his guidance, support and encouragement throughout this research work. His enormous trust and relentless efforts have helped to see me complete this research activity. I would also like to thank my colleagues at the National Centre for Prevention and Control of Diabetes and Cardiovascular Diseases, Vaiola Hospital, for their great support throughout this work. I would like to thank Associate Professor Ruth Colagiuri for the on-going support, encouragement and willingness to maximize my working opportunity. Her commitment and dedication for excellence have encouraged me to work through this research. I would also like to thank the survey team and staff of Diabetes Centre, Prince of Wales Hospital for their support and assistance throughout this research. I am extremely grateful to the survey statistician, Zafrul Huzzain for his expertise and help in statistical theory, analysis and application. I also would like to thank the Ministry of Health and the people of Tonga for allowing me to undertake this research work, and the Australian government for providing financial support. I also would like to thank my employer in New Zealand, TaPasefika Health Trust and South Seas Health Care for supporting me in my study. Finally, I would like to acknowledge my sincere gratitude and appreciation to my parents, the late Sione and Salote Muimuiheata, and my sisters, Popua, Mele, Simaima, Temaleti, Hulita, my brothers, Futa, Kava, Niu, and my in-laws, nieces and nephews for their love, prayers and support. Special thanks to all my friends and relatives for all their contribution and support. Above all, I am forever grateful to God for his wisdom and guidance as he led me through this life and may his name be glorified and honoured. iv Table of Contents Page Tile Page i Abstract ii Acknowledgment iv Table of Contents v List of Figures xii List of Tables xiii Certificate of Originality xvi Glossary of Acronyms xvii CHAPTER 1 INTRODUCTION 1.1 About Tonga: The Land and it‟s people 1 1.1.1. Geography 1 1.1.2. Population 3 1.1.3. History and Culture 4 1.1.4. Infrastructure 5 1.1.5. Health Status in Tonga 6 1.1.5.1. Mortality and Morbidity Rates in Tonga 6 1.2. Diabetes and Non-Communicable Diseases 7 1.2.1. Diabetes 7 1.2.1.1. Definition 7 1.2.1.2. Classification 8 1.2.1.2.1. Type 1 Diabetes 8 1.2.1.2.2. Type 2 Diabetes 9 1.2.1.2.3. Gestational Diabetes Mellitus 9 1.2.1.2.4. Other Specific Types 9 1.2.1.2.5. Impaired Glucose Regulation –Impaired 10 Glucose Tolerance and Impaired Fasting Glycaemia 1.2.2 Diabetes and Cardiovascular Disease in Tonga and in the 11 Pacific Countries v 1.2.2.1. Brief Review 11 1.2.2.2. Diabetes Prevalence in the Pacific Countries 12 1.2.2.3. Diabetes Prevalence in Tonga 14 1.2.2.4. Prevalence of Diabetes Complications in Tonga 15 1.2.3. Risk Factors for Diabetes and Cardiovascular Disease 15 1.2.3.1. Brief Overview 15 1.2.3.2. The Metabolic Syndrome 16 1.2.3.3. Overweight and Obesity 18 1.2.3.3.1. Brief Overview 18 1.2.3.3.2. Body Mass Index 19 1.2.3.3.3. Waist Circumference and Waist to Hip Ratio 20 1.2.3.3.4. Prevalence of Overweight and Obesity in 22 Pacific Countries 1.2.3.3.5. Prevalence of Overweight and Obesity 22 in Tonga 1.2.3.4. Thrifty Genotype 27 1.2.3.5. Hypertension 28 1.2.3.5.1. Brief Overview 28 1.2.3.5.2. Hypertension in Tonga 28 1.3. Food and Nutrient Intake 30 1.3.1. Brief Overview 30 1.3.1.1. Food and Culture 31 1.3.1.2. Food Groups 32 1.3.1.3. Food and Nutrition Guidelines 33 1.3.1.4. Recommended Dietary Intake 34 vi 1.3.2. Nutrient Intake and Non-Communicable Diseases 35 1.3.2.1. Nutrients, Diabetes and Cardiovascular Disease Risk Factors 37 1.3.2.1.1. Current nutrition recommendations for diabetes and cardiovascular risk factors 38 1.3.2.1.2. Total Energy Intake 38 1.3.2.1.3. Dietary Fats 39 1.3.2.1.4. Carbohydrates 40 1.3.2.1.5. Dietary Fibre 41 1.3.2.1.6. Glycaemic index 42 1.3.2.1.7. Proteins 43 1.3.2.1.8. Vitamins and Minerals 43 1.3.2.2.Food and Nutrient Intake in the Pacific Countries 44 1.3.2.3.Food and Nutrient Intake in Tonga 46 1.4. Lifestyle Risk Factors 49 1.4.1. Exercise and Physical Activity 49 1.4.1.1. Brief Overview 49 1.4.1.2. Physical Activity, Diabetes and Cardiovascular Disease 50 1.4.1.3. Physical Activity in Tonga 50 1.4.2. Smoking 51 1.4.2.1. Brief Overview 51 1.4.2.2. Smoking, Diabetes and Cardiovascular Disease 51 1.4.2.3. Smoking in Tonga and Pacific Countries 52 1.4.2.4. Smoking and Religion 53 1.4.3. Alcohol 54 1.4.3.1. Brief Overview 54 1.4.3.2. Alcohol, Diabetes and Cardiovascular Disease 54 1.4.3.3. Alcohol in Tonga and Pacific Countries 56 1.4.3.4. Alcohol and Culture 58 vii CHAPTER 2 OBJECTIVES 2.1. Brief Overview 59 2.2. Objectives and Aims 59 2.3. My Role in the Study 60 CHAPTER 3 STUDY DESING AND METHODS 3.1. Brief Overview 61 3.2. Timing of Survey 61 3.3. Survey Team 62 3.4. Subject Selection 62 3.4.1. Exclusion Criteria 63 3.4.2. Household Contact 63 3.5. Promotion of the Survey 64 3.6. Survey Procedure 64 3.6.1. Staff Training 64 3.6.2. Data Collection 65 3.6.2.1.