THE NUTRITION SOCIETY TEXTBOOK SERIES

Public HealthNutritionEdited by Michael J. Gibney,Barrie M. Margetts and John M. Kearney

Public Health Nutrition

Edited on behalf of The Nutrition Society by

Michael J Gibney, Barrie M Margetts, John M Kearney and Lenore Arab

BlackwellScience

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© The Nutrition Society 2004

Published by Blackwell Sciencea Blackwell Publishing companyEditorial offices:Blackwell Science Ltd, 9600 Garsington Road,Oxford OX4 2DQ, UK

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First published 2004

Library of Congress Cataloging-in-Publication DataPublic health nutrition / edited on behalf of The Nutrition Society by Michael J.Gibney … [et al.].

p. cm.Includes bibliographical references and index.ISBN 0-632-05627-4 (pbk. : alk. paper)

1. Nutritionally induced diseases. 2. Nutrition. 3. Public health. I. Gibney,Michael J. II. Nutrition Society (Great Britain)RA645.N87P83 2004 616.3′9--dc22 2004010644

ISBN 0-632-05627-4

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The Human Nutrition Textbook Series

The International Scientific Committee

Editor-in-ChiefProfessor Michael J GibneyTrinity College, Dublin, Ireland

Assistant EditorJulie DowsettTrinity College, Dublin, Ireland

Professor Lenore ArabUniversity of North Carolina, USA

Professor Yvon CarpentierUniversité Libre de Bruxelles, Belgium

Professor Marinos EliaUniversity of Southampton, UK

Professor Frans J KokWageningen University, Netherlands

Professor Olle LjungqvistErsta Hospital & Huddinge University Hospital, Sweden

Professor Ian A MacdonaldUniversity of Nottingham, UK

Professor Barrie M MargettsUniversity of Southampton, UK

Professor Kerin O’DeaMenzies School of Health Research, Darwin, Australia

Dr Helen M RocheTrinity College, Dublin, Ireland

Professor Hester H VorsterPotchefstroom, South Africa

Dr John M KearneyDublin Institute of Technology, Ireland

Textbook Editors

Introduction to Human NutritionEditor-in-ChiefProfessor Michael J GibneyTrinity College, Dublin, Ireland

Professor Hester H VorsterPotchefstroom, South Africa

Professor Frans J KokWageningen University,Netherlands

Nutrition and MetabolismEditor-in-ChiefProfessor Michael J GibneyTrinity College, Dublin, Ireland

Professor Ian A MacdonaldUniversity of Nottingham, UK

Dr Helen M RocheTrinity College, Dublin, Ireland

Public Health NutritionEditor-in-ChiefProfessor Michael J GibneyTrinity College, Dublin, Ireland

Professor Barrie M MargettsUniversity of Southampton, UK

Professor Lenore ArabUniversity of North Carolina, USA

Dr John KearneyDublin Institute of Technology, Ireland

Clinical NutritionEditor-in-ChiefProfessor Michael J GibneyTrinity College, Dublin, Ireland

Professor Marinos EliaUniversity of Southampton, UK

Professor Olle LjungqvistErsta Hospital & Huddinge University Hospital, Sweden

Julie DowsettTrinity College, Dublin, Ireland

www.nutritiontexts.comA unique feature of The Nutrition Society Textbook Series is that each chapter will have its own web pages, acces-sible at www.nutritiontexts.com. In the course of time, each will have downloadable teaching aids, suggestionsfor projects, updates on the content of each chapter and sample multiple choice questions. With input from teach-ers and students we will have a vibrant, informative and social website.

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Introduction to Human Nutrition

Introduction to human nutrition: a global perspective on food and nutrition

Body compositionEnergy metabolismNutrition and metabolism of proteins and amino acidsDigestion and metabolism of carbohydratesNutrition and metabolism of lipidsDietary reference standardsThe vitaminsMinerals and trace elementsMeasuring food intakeFood compositionFood policy and regulatory issuesNutrition research methodologyFood safety: a public health issue of growing

importanceFood and nutrition: the global challenge

Public Health Nutrition

An overview of public health nutritionNutritional epidemiologyAssessment of nutritional status in individuals and

populationsAssessment of physical activityPublic health nutrition strategies for intervention

at the ecological levelPublic health nutrition strategies for intervention

at the individual levelDietary guidelinesFood choicePublic health aspects of overnutritionPublic health aspects of undernutritionVitamin A deficiencyIodine and iron-deficiency disordersIron-deficiency anemiasFear of fatness and fad slimming dietsNutrition and child developmentInfant feedingAdverse outcomes in pregnancy: the role of folate

and related B-vitaminsMaternal nutrition, fetal programming and adult

chronic diseaseCardiovascular diseaseDiabetes mellitusCancer and dietDisease prevention: osteoporosis and hip fracture

Nutrition and Metabolism

Core concepts of nutritionMolecular nutritionIntegration of metabolism 1: EnergyIntegration of metabolism 2: Protein and amino acidsIntegration of metabolism 3: MacronutrientsPregnancy and lactationGrowth and agingNutrition and the brainThe sensory systems: taste, smell, chemesthesis and visionThe gastrointestinal tractThe cardiovascular systemThe skeletal systemThe immune and inflammatory systemsPhytochemicalsThe control of food intakeOvernutritionUndernutritionExercise performance

Clinical Nutrition

General principles of clinical nutritionMetabolic and nutritional assessmentOvernutritionUndernutritionMetabolic disordersEating disordersAdverse reactions to foodsNutritional supportEthical and legal issuesGastrointestinal tractThe liverThe pancreasThe kidneyBlood and bone marrowThe lungImmune and inflammatory systemsHeart and blood vesselsThe skeletonPerioperative nutritionInfectious diseasesMalignant diseasesPediatric nutritionCystic fibrosisWater and electrolytesClinical cases

The Human Nutrition Textbook series comprises:

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ContentsSeries Foreword xi

Preface xii

Contributors xiii

1. An Overview of Public Health Nutrition 1Barrie M Margetts1.1 Introduction 11.2 Organization of the book 31.3 Definitions used in public health 41.4 What are the key public health problems? 71.5 Food and nutrition policy 101.6 The public health nutrition cycle 121.7 Step 1: Identify key nutrition-related problem 121.8 Step 2: Set goals and broad aims 151.9 Step 3: Define objectives 161.10 Step 4: Create quantitative targets 161.11 Step 5: Develop program 181.12 Step 6: Implementation 221.13 Step 7: Evaluation 23

Further reading 25

2. Nutritional Epidemiology 26Michael Nelson, Shirley AA Beresford and John M Kearney2.1 Introduction 262.2 Types of study 312.3 Study design: sampling, study size and power 342.4 Measuring exposure 392.5 Measuring outcomes 502.6 Measuring diet–disease (exposure–outcome) associations 542.7 Interpretation of associations 602.8 Expressing results from nutritional epidemiological studies 632.9 Perspectives on the future 64

Further reading 65

3. Assessment of Nutritional Status in Individuals and Populations 66Ruth E Patterson and Pirjo Pietinen3.1 Introduction 663.2 Dietary assessment 673.3 Biomarkers as measures for the assessment of nutritional status 753.4 Anthropometric and other clinical measures 773.5 Error in methods of assessment of nutritional status 783.6 Perspectives on the future 81

Further reading 81

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4. Assessment of Physical Activity 83Michael Sjöström, Ulf Ekelund and Agneta Yngve4.1 Introduction 834.2 Definition of commonly used terms 844.3 Dimensions of physical activity 864.4 Reliability and validity of physical activity assessment instruments 904.5 Physical activity assessment methods 914.6 Perspectives on the future 104

Further reading 104

5. Public Health Nutrition Strategies for Intervention at the Ecological Level 106Kim D Reynolds, Knut-Inge Klepp and Amy L Yaroch5.1 Introduction 1065.2 Definition of the ecological approach 1065.3 Individual versus ecological approaches 1075.4 Key principles in the ecological approach 1085.5 Intervention 1105.6 Advantages and disadvantages of this approach 1115.7 Guidelines for using the ecological approach to design nutrition

interventions 1115.8 Ethical issues to consider 1125.9 Ecological interventions to change eating habits 1135.10 Perspectives on the future 119

Further reading 119

6. Public Health Nutrition Strategies for Intervention at the Individual Level 120Barrie M Margetts6.1 Introduction 1206.2 Interventions of supplementary feeding, foods or nutrients 1236.3 Changing behavior without giving foods 1246.4 Evaluation of programs and interventions 1306.5 Perspectives on the future 131

Further reading 132

7. Dietary Guidelines 133Michael J Gibney and Petro Wolmarans7.1 Introduction 1337.2 Overview of dietary recommendations 1337.3 Quantitative dietary guidelines 1347.4 Qualitative dietary guidelines 1377.5 Steps involved in devising food-based dietary guidelines 1397.6 Visual presentations of food guides related to dietary guidelines 1437.7 Perspectives on the future 143

Further reading 143

vi Contents

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8. Food Choice 144David N Cox and Annie S Anderson8.1 Introduction 1448.2 The study of food choice 1458.3 Population issues affecting food choice 1478.4 Individual issues affecting food choice 1528.5 Perspectives on the future 163

Further reading 165

9. Public Health Aspects of Overnutrition 167Jacob C Seidell and Tommy LS Visscher9.1 Introduction 1679.2 Macronutrients, excess energy intake and overweight 1709.3 Obesity as a determinant of mortality and morbidity 1719.4 Perspectives on the future 177

Further reading 177

10. Public Health Aspects of Undernutrition 178Mark J Manary and Noel W Solomons10.1 Introduction 17810.2 Definitions of undernutrition 17810.3 Clinical syndromes of undernutrition 17910.4 Micronutrient deficiency: “hidden hunger” 18010.5 Time trends and contemporary prevalences 18110.6 Etiology: determinants and conditioning factors for undernutrition 18110.7 Public health consequences of undernutrition 18710.8 Policy and programmatic issues in preventing undernutrition 18810.9 Policy and programmatic issues in reversing undernutrition 19010.10 Perspectives on the future 191

Further reading 191

11. Vitamin A Deficiency 192Faruk Ahmed and Ian Darnton-Hill11.1 Introduction 19211.2 Consequences of vitamin A deficiency 19411.3 Epidemiology 20011.4 Prevention and control 20311.5 Assessment of vitamin A status 20811.6 Monitoring and evaluation 21211.7 Perspectives on the future 214

Further reading 215

12. Iodine and Iodine-deficiency Disorders 216Clive E West, Pieter L Jooste and Chandrakant S Pandav12.1 Introduction 21612.2 Definition of iodine deficiency 21612.3 Clinical features 219

Contents vii

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12.4 Iodine metabolism 21912.5 Reference intakes for iodine 22112.6 Public health aspects to iodine deficiency 22212.7 Management of iodine deficiency 22312.8 Assessment and elimination of iodine deficiency disorders 22512.9 Perspectives on the future 226

Further reading 226

13. Iron-deficiency Anemias 227Kamasamudram Vijayaraghavan13.1 Introduction 22713.2 Definition and clinical features of iron-deficiency anemia 22813.3 Iron metabolism 23013.4 Reference intakes for iron 23213.5 Public health implications of iron-deficiency anemia 23213.6 Perspectives on the future 234

Further reading 235

14. Fear of Fatness and Fad Slimming Diets 236Mary AT Flynn14.1 Introduction 23614.2 Epidemiology 23714.3 Life-cycle fatness trends 23714.4 Definitions and descriptions 23814.5 Etiology 24114.6 Consequences for public health 24214.7 Prevention strategies 24414.8 Assessing body image 24514.9 Perspectives on the future 246

Further reading 246

15. Nutrition and Child Development 247Helen Baker-Henningham and Sally Grantham-McGregor15.1 Introduction 24715.2 Child development and the role of the environment 24815.3 Possible mechanisms linking undernutrition to poor development 24815.4 Prevalence of nutritional deficiencies 24915.5 Intrauterine growth retardation 25015.6 Breast-feeding and its influence on child development 25115.7 Wasting, stunting and severe clinical malnutrition 25315.8 Iron-deficiency anemia 25615.9 Iodine deficiency 25915.10 Zinc deficiency 26015.11 Vitamin A deficiency 26015.12 Studies on the effects of short-term hunger and school feeding 26115.13 Perspectives on the future 262

Further reading 263

viii Contents

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16. Infant Feeding 264Anna Coutsoudis and Jane Bentley16.1 Introduction 26416.2 Role and importance of breast-feeding 26516.3 Barriers to successful breast-feeding 26816.4 Breast-feeding challenges 27116.5 Potential feeding difficulties 27416.6 Breast-feeding and human immunodeficiency virus transmission 27516.7 Infant feeding after 6 months 27716.8 Monitoring the child’s growth: the road-to-health chart 28016.9 Perspectives on the future 281

Further reading 282

17. Adverse Outcomes in Pregnancy: The Role of Folate and Related B-Vitamins 283John Scott and Helene McNulty17.1 Introduction 28317.2 Biochemical basis for the role of folate in adverse outcomes of pregnancy 28417.3 Evidence that folate and other related vitamins play a protective role against

adverse outcomes of pregnancy 29017.4 Prevention of folate-responsive adverse outcomes of pregnancy 29517.5 Perspectives on the future 300

Further reading 301

18. Maternal Nutrition, Fetal Programming and Adult Chronic Disease 302David JP Barker and Keith M Godfrey18.1 Introduction 30218.2 Observations establishing the link between size at birth and later

cardiovascular disease 30318.3 Potential confounding influences 30518.4 Findings for particular cardiovascular and metabolic disorders 30518.5 Determinants of fetal growth and programming: the importance of

fetal nutrition 31118.6 Maternal influences on fetal nutrition 31218.7 Perspectives on the future 316

Further reading 316

19. Cardiovascular Disease 317Jim Mann19.1 Introduction 31719.2 Epidemiology 31819.3 Correlations between coronary heart disease rates and food intake 31919.4 Prospective observation of subjects for whom diet histories are

available 32019.5 Cardiovascular risk factors and their nutritional determinants 32119.6 Clinical trials of cardiovascular risk reduction by dietary modification 32319.7 Nutritional strategies for high-risk populations 32619.8 Perspectives on the future 328

Further reading 328

Contents ix

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20. Diabetes Mellitus 330Ambady Ramachandran and Chamukuttan Snehalatha20.1 Introduction 33020.2 Classification of diabetes 33020.3 Diagnosis of diabetes 33120.4 Risk factors for the development of diabetes 33220.5 Diabetes as a public health issue 33420.6 Prevention and management of diabetes 33620.7 Scope for primary prevention of diabetes 33920.8 Perspectives on the future 340

Further reading 340

21. Cancer and Diet 341Lenore Arab and Susan Steck-Scott21.1 Introduction 34121.2 Mechanisms of effect of diet 34121.3 Carcinogenesis: initiation, promotion and progression to metastases 34321.4 Gene–nutrient interactions in carcinogenesis 34421.5 Epidemiological studies of diet and cancer 34621.6 Dietary constituents of interest 35021.7 Prevention: preventive potential 35421.8 Prevention guidelines for individuals and populations 35521.9 Perspectives on the future 355

Further reading 356

22. Disease Prevention: Osteoporosis and Hip Fracture 357Nicholas Harvey and Cyrus Cooper22.1 Introduction 35722.2 Definition 35722.3 Epidemiology: the scale of the problem 35822.4 The biology of bone health 36322.5 Perspectives on the future 369

Further reading 369

Appendix 370

Index 373

x Contents

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Series ForewordThe early decades of the twentieth century were aperiod of intense research on constituents of foodessential for normal growth and development, and sawthe discovery of most of the vitamins, minerals, aminoacids and essential fatty acids. In 1941, a group of lead-ing physiologists, biochemists and medical scientistsrecognized that the emerging discipline of nutritionneeded its own learned society and The Nutrition Soci-ety was established. Our mission was, and remains,“toadvance the scientific study of nutrition and its applica-tion to the maintenance of human and animal health”.The Nutrition Society is the largest learned society fornutrition in Europe and we have over 2000 membersworldwide. You can find out more about the Societyand how to become a member by visiting our websiteat www.nutsoc.org.uk

The ongoing revolution in biology initiated by large-scale genome mapping and facilitated by the develop-ment of reliable, simple-to-use molecular biologicaltools makes this a very exciting time to be working innutrition. We now have the opportunity to obtain amuch better understanding of how specific genes inter-act with nutritional intake and other lifestyle factorsto influence gene expression in individual cells and tis-sues and, ultimately, affect our health. Knowledge ofthe polymorphisms in key genes carried by a patientwill allow the prescription of more effective, and safe,dietary treatments. At the population level, molecularepidemiology is opening up much more incisiveapproaches to understanding the role of particulardietary patterns in disease causation. This excitementis reflected in the several scientific meetings that TheNutrition Society, often in collaboration with sisterlearned societies in Europe, organizes each year. Weprovide travel grants and other assistance to encour-age students and young researchers to attend and par-ticipate in these meetings.

Throughout its history a primary objective of theSociety has been to encourage nutrition research andto disseminate the results of such research. Our firstjournal, The Proceedings of The Nutrition Society,recorded, as it still does, the scientific presentations

made to the Society. Shortly afterwards, The BritishJournal of Nutrition was established to provide amedium for the publication of primary research on allaspects of human and animal nutrition by scientistsfrom around the world. Recognizing the needs of stu-dents and their teachers for authoritative reviews ontopical issues in nutrition, the Society began publish-ing Nutrition Research Reviews in 1988. Morerecently, we launched Public Health Nutrition, the firstinternational first journal dedicated to this importantand growing area. All of these journals are available inelectronic, as well as in the conventional paper formand we are exploring new opportunities to exploit theweb to make the outcomes of nutritional research morequickly and more readily accessible.

To protect the public and to enhance the careerprospects of nutritionists, The Nutrition Society iscommitted to ensuring that those who practice asnutritionists are properly trained and qualified. Thisis recognized by placing the names of suitably quali-fied individuals on our professional registers and by theaward of the qualifications Registered Public HealthNutritionist (RPHNutr) and Registered Nutritionist(RNutr). Graduates with appropriate degrees but whodo not yet have sufficient postgraduate experience canjoin our Associate Nutritionist registers. We undertakeaccreditation of university degree programs in publichealth nutrition and are developing accreditationprocesses for other nutrition degree programs.

Just as in research, having the best possible tools isan enormous advantage in teaching and learning. Thisis the reasoning behind the initiative to launch thisseries of human nutrition textbooks designed for useworldwide. The Society is deeply indebted to its for-mer President, Professor Mike Gibney, for his foresight,and to him and his team of editors for their innova-tive approaches and hard work in bringing this majorpublishing exercise to successful fruition. Read, learnand enjoy.

John MathersPresident of The Nutrition Society

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PrefaceThis book represents the third in a series of four forhonors or masters level students of nutrition. The firstbook serves as a broad introduction, not just for nutri-tion students, but also for students of disciplines suchas nursing, pharmacy, food science and agriculture. Allthe ensuing books are aimed at nutrition students. Thesecond textbook, Nutrition and Metabolism, providesstudents with the biological basis of nutrition in healthand disease. Thereafter, most students will make achoice to pursue either a clinical stream or a publichealth nutrition stream. The present book is focusedon the latter, a subject that is growing in importance,taking into account the real potential to reduce the bur-den on noncommunicable chronic disease throughdiet. The Nutrition Society has championed thedevelopment of recognition of public health nutritionas a specialized discipline in the field, complementingthe established specialty of clinical nutrition where the target audience is an individual patient on a one-to-one basis. In the case of public health nutrition thetarget audience is the population as a whole or specificsubpopulations. The textbook is structured to beginwith an overview taking students through a cycle of

procedures, which should ideally be a feature of anyprogram of public health nutrition. The first eightchapters of the book describe the skills needed in pub-lic health nutrition. The next six outline the major public health nutrition problems arising from over-nutrition and from undernutrition. Maternal and childhealth issues are covered in the next four chapters, andsome major diseases, cancer, diabetes, heart disease andosteoporosis, are dealt with in the final four chapters.As has been pointed out in the prefaces to the first twobooks in this series, there will be some overlap, but stu-dents will find the orientation different for similar sub-jects across texts. In some chapters, the public healthnutrition element is accompanied by relevant materialin clinical nutrition or in molecular nutrition, whichwill help students appreciate the links between all ele-ments of nutrition.

The editors once again express their sincere thanksto their Assistant Editor Julie Dowsett and her heroichusband Greg.

Michael J GibneyEditor-in-Chief

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Contributors

Dr Faruk AhmedNutrition Program – Division of International HealthSchool of Population HealthPublic Health BuildingHerston, Queensland, Australia

Dr Annie S AndersonCentre for Public Health Nutrition ResearchDepartment of MedicineUniversity of DundeeNinewells Hospital and Medical SchoolDundee, UK

Professor Lenore ArabAmgen, Inc.Thousand OaksCalifornia, USAProfessor of Nutrition and EpidemiologyUNC School of Public HealthChapel Hill, North Carolina, USA

Dr Helen Baker-HenninghamCentre of International Child HealthInstitute of Child HealthLondon, UK

Professor David JP BarkerMRC Environmental Epidemiology UnitSouthampton General HospitalSouthampton, UK

Ms Jane BentleyDepartment of Pediatrics and Child HealthUniversity of NatalDurban, South Africa

Dr Shirley AA BeresfordDepartment of EpidemiologySchool of Public Health and Community MedicineUniversity of WashingtonSeattle, Washington, USA

Professor Cyrus CooperProfessor of RheumatologyMRC Epidemiology Resource CentreUniversity of SouthamptonSouthampton General HospitalSouthampton, UK

Professor Anna CoutsoudisDepartment of Pediatrics and Child HealthUniversity of NatalDurban, South Africa

Dr David N CoxCSIRO Health Sciences and NutritionAdelaide, SA, Australia

Dr Ian Darnton-HillNutrition Section, UNICEFNew York, USA

Dr Ulf EkelundKarolinska InstitutetUnit for Preventive NutritionDepartment of Biosciences at NovumHuddinge, Sweden

Dr Mary AT FlynnCoordinator, Nutrition and Active LivingCalgary Health RegionAdjunct ProfessorDepartment of Agriculture and Nutritional SciencesUniversity of Alberta andDepartment of Community Health SciencesUniversity of Calgary, Alberta, Canada

Professor Michael J GibneyDepartment of Clinical MedicineTrinity Centre for Health Sciences St James’ HospitalDublin, Ireland

Dr Keith M GodfreyMRC Clinical ScientistMRC Environmental Epidemiology UnitSouthampton General HospitalSouthampton, UK

Professor Sally Grantham-McGregorCentre of International Child HealthInstitute of Child HealthLondon, UK

Dr Nicholas HarveyMRC Epidemiology Resource CentreUniversity of SouthamptonSouthampton General HospitalSouthampton, UK

Dr Pieter L JoosteNational Intervention Research UnitMedical Research CouncilTygerberg, Cape Town, South Africa

Dr John M KearneyDepartment of Biological ScienceDublin Institute of TechnologyDublin, Ireland

Dr Knut-Inge KleppDepartment of Nutrition University of OsloOslo, Norway

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Professor Helene McNultySchool of Biomedical SciencesUniversity of Ulster at ColeraineLondonderry, UK

Dr Mark ManaryDepartment of PediatricsWashington UniversitySchool of MedicineSt. Louis, Missouri, USA

Professor Jim MannDepartment of Human NutritionUniversity of OtagoDunedin, New Zealand

Professor Barrie M MargettsInstitute of Human NutritionUniversity of SouthamptonSouthampton, UK

Dr Michael NelsonDepartment of Nutrition and DieteticsKing’s College LondonLondon, UK

Dr Chandrakant S PandavRegional CoordinatorICCIDD, South Asia and Pacific RegionNew Delhi, India

Dr Ruth E PattersonResearch Associate ProfessorDepartment of EpidemiologyUniversity of WashingtonSeattle, Washington, USA

Dr Pirjo PietinenNational Public Health InstituteMannerheimintieHelsinki, Finland

Dr Ambady RamachandranDiabetes Research Centre and M. V. Hospital for DiabetesRoyapuram, Chennai, India

Dr Kim D ReynoldsUniversity of Southern CaliforniaInstitute for Health Promotion and DiseasePrevention ResearchLos Angeles, California, USA

Professor John ScottBiochemistry DepartmentTrinity CollegeDublin, Ireland

Dr Jacob C SeidellDepartment for Nutrition and HealthFree UniversityAmsterdam, The Netherlands

Dr Michael SjöströmKarolinska InstitutetUnit for Preventive NutritionDepartment of Biosciences at NovumHuddinge, Sweden

Dr Chamukuttan SnehalathaDiabetes Research Centre and M. V. Hospital for DiabetesRoyapuram, Chennai, India

Dr Noel W SolomonsDirectorCenter for Studies of Sensory Impairment(CESSIAM)Guatamala City, Guatamala

Dr Susan Steck-ScottDepartment of NutritionUniversity of North CarolinaChapel Hill, North Carolina, USA

Dr Kamasamudram VijayaraghavanSenior Deputy DirectorNational Institute of NutritionIndian Council of Medical ResearchHyderbad, India

Dr Tommy LS VisscherDepartment for Nutrition and HealthFree UniversityAmsterdam, The Netherlands

Dr Clive E WestDivision of Human Nutrition and EpidemiologyWageningen Agricultural UniversityWageningen, The Netherlands

Dr Petro WolmaransNational Research Programme for Nutritional InterventionMedical Research CouncilTygerberg, South Africa

Dr Amy YarochNational Cancer Institute Division of Cancer control and Population SciencesBethesda, Maryland, USA

Dr Agneta YngveKarolinska InstitutetUnit for Preventive NutritionDepartment of Biosciences at NovumHuddinge, Sweden

xiv Contributors

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1.1 Introduction

The knowledge base underpinning the public healthnutritionist professional is developed over years and builton a foundation of biology, biochemistry, physiology andbasic nutritional sciences, as well as an understanding of social anthropology. The development of the founda-tions is not within the scope of this book. Many of thesecompetencies are covered in the accompanying text-books, particularly the Introduction to Human Nutritionand Nutrition and Metabolism. The aims of this book areto cover the skills needed in public health nutrition andto provide a coherent structure to enable the reader:

• to identify nutrition-related public health problemsrelevant at the local, regional, national and interna-tional levels

• to identify causes of these problems

• to develop strategies to deal with these problems

• to evaluate the impact of these strategies

• to understand the process whereby research-basedevidence provides a basis for the development ofpublic health policy

• ultimately, to improve nutrition-related health byapplying evidence to action to solve problems.

Public health nutrition is about applying knowledgeto the solution of nutrition-related health problems.Often when confronted with a problem, people do not know where to start, become lost in the detail, andsometimes miss the obvious and simple critical stepsthat will really make a difference. In this introductorychapter an attempt is made to provide a framework forthe reader to think logically and systematically: to pro-vide a template to proceed in a logical and systematicway. People often want to jump in with what they thinkis the solution to the problem confronting them; theaim here is to help readers to think before they jump.It is now fashionable to talk about an evidence-basedapproach to public health. All this really means is find-ing out what others already know, putting aside one’sprejudices, assessing the situation objectively, and coming up with the best and most effective solution.It may seem obvious, but there is no need to fix thatwhich is not broken. Rather, the effort should be to try to identify the key rate-limiting step (or major

1An Overview of Public Health Nutrition

Barrie M Margetts

Key messages

• Public health nutrition is the promotion of good healththrough primary prevention of nutrition-related illnessin the population.

• Public health nutrition builds on a foundation of bio-logical and social sciences, depends on epidemiologicalevidence and involves the development and implemen-tation of programs to improve and maintain health.

• Performance as a public health nutritionist requires aspecific set of knowledge- and skill-based competencies

to implement all stages of the public health nutritioncycle.

• It is essential to develop appropriate knowledge, atti-tudes, understanding and professional skills to practiceas a public health nutritionist.

• An appreciation and critical evaluation of the impact ofresearch on the practice of public health nutrition alsoneeds to be developed.

© 2004 BM Margetts. For more information on this topic visit www.nutritiontexts.com

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constraint to behavior) in the causal pathway and fixthat. Our knowledge as to what the rate-limiting stepis can never be perfect, so some judgment is required.However, the more systematically the evidence is gath-ered and reviewed, both in terms of the causal path-way and in terms of effective interventions, the moreeffective the effort will be in achieving the targetedhealth gains. The aim of this book is to give the stu-dent the knowledge and skills to think clearly abouthow to solve problems. The primary purpose ofgood nutrition is to maintain health and well-being.Nutrition is more than the food supply: it reflects theinteraction between what we eat, and the metabolicdemands of the body to maintain functional capacity.The basic, underlying and immediate causes of mal-nutrition are summarized in Figure 1.1. If nutrition isonly thought of as the supply side of this balance this is likely to lead to a misunderstanding of the key

rate-limiting steps that link good nutrition to well-being. It is also important to consider the social as wellas the biological context within which individuals liveand interact in society. While it is beyond the scope ofthis text to cover all aspects of whole-body integratedmetabolism, some understanding of the underlyingmechanisms that link diet and style of living to healthis required to understand whether the lifestyle changesthat are being suggested to improve health make sensebiologically. Inevitably, good nutrition-related healthis about understanding the relationships between thebiological and sociological context within whichindividuals live and interact in society. Where foodsupply is limited there is a clear biological imperativeto obtain enough to eat; where supply is in excess,social imperatives that restrain or limit behavior comeinto play. In all societies, especially those in transition,there is a complex mix of problems of overnutrition

2 Public health nutrition

Malnutrition and death

Inadequatedietary intake

Disease

Political and ideological superstructure

Economic structure

Immediatecauses

Underlyingcauses

Basiccauses

Inadequatecare for mothers

and children

Potential resources

Insufficient healthservices and

unhealthyenvironment

Inadequateaccess to food

Inadequate education

Formal and nonformalinstitutions

Figure 1.1 United Nations Children’s Fund (UNICEF) conceptual model.

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and undernutrition occurring in close proximity. Thejob of the public health nutritionist is to try to under-stand this complexity and to provide guidance as towhat is best for most people. This book aims to helpstudents in this task.

1.2 Organization of the book

There are 22 chapters in this book. The first eight chapters are designed to develop the skills required to understand how to identify and subsequently todevelop approaches to address the major nutrition-related public health problems. Chapter 2 on nutritionalepidemiology addresses the skills required for thedesign of appropriate studies, for conducting nutri-tional surveillance and the development of researchprotocols. It also reviews the analytical skills requiredin the use of nutritional and other relevant data anddatabases including the statistical issues, samplingstudy size and power, determination and applica-tion of appropriate statistical analytical techniques.Chapter 3 defines and describes the tools used to assessnutritional status at the individual and populationlevels. The emphasis in Chapter 3 is on assessment ofdietary intake. Chapter 4 describes the methods andapproaches used to assess physical activity. Nutritionalstatus embraces an understanding of the dynamicbetween supply and demands, and increasingly it isbecoming clear that, particularly in terms of under-standing energy balance, it is essential to assess bothintake and expenditure, and factors that affect both.Identifying the problem is only the first step in solvingthe problem; Chapters 5 and 6 describe the approachesto developing effective interventions in groups andindividuals, respectively and Chapter 7 describes howto develop and present dietary guidelines that com-municate dietary advice in the most sensible way pos-sible, once it is clear what is the required or optimalnutritional pattern or profile. There is considerableoverlap in the approaches used, broadly, the aim shouldbe to use that approach which is most effective for mostpeople, or different approaches for different groups ifthere appear to be different constraints in subgroups.Understanding the constraints on behavior and factorsaffecting food choice is the subject of Chapter 8.

Chapters 9–14 describe different aspects of mal-nutrition. Chapters 9 (overnutrition) and 10 (under-nutrition) describe the development of aspects of whatmight be termed macronutrient malnutrition, while

Chapters 11–13 describe specific micronutrient mal-nutrition deficiencies. Increasingly, it is becoming clearthat undernutrition and overnutrition occur in dif-ferent groups of people in the same countries, and that macronutrient and micronutrient imbalances canoccur in the same people. Chapter 14 describes thecomplex area of eating disorders, which lead mainlyto undernutrition of both macronutrients and micro-nutrients, but with different causes, and tending toaffect different groups within a society, from thosedescribed in Chapters 9–13.

Chapters 15–18 describe different aspects of mater-nal and child health; Chapter 15 focuses on aspects of cognitive development, Chapter 16 focuses on theimportance of infant feeding, Chapter 17 focuses onadverse outcomes of pregnancy in relation to folate andrelated B-group vitamins, and Chapter 18 describes the concepts that underpin fetal programming. Takentogether, these chapters highlight the importance ofachieving the optimal nutrient supply at the criticaltime to enhance and maintain function. This may beconsidered a key part, or first step of a life-courseapproach, recognizing that what happens after certaincritical events is constrained by these earlier events and interacts with current behavior. Current health and well-being cannot be fully explained by currentbehavior alone, and early events (programming, earlyexposure) influence the way in which an individual andsociety react to what appears to be the same exposure.This may be described as explaining the sources ofheterogeneity within a population, which may be alsoa mix of different levels of the expression of genes,gene–nutrient and nutrient–gene interactions.

Chapters 19–22 describe the main chronic diseasethat affect large numbers of people around the world;Chapter 19 describes cardiovascular diseases, Chapter 20 diabetes, Chapter 21 cancer and Chapter 22 osteo-porosis. Already these chronic diseases affect more people in developing than in developed countries, andit is likely that this will increase as the nutrition tran-sition continues in developing countries and rates ofchronic diseases decline in developed countries.

There is no specific chapter on communicable orinfectious diseases; the impact of these is coveredextensively in the chapters on undernutrition. The aimhas been to use major health problems as a way of illus-trating approaches and ways of thinking that shouldhelp the reader to think about how to understand and address specific problems.

An overview of public health nutrition 3

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1.3 Definitions used in public health

Public health nutritionA public health nutrition approach focuses on the promotion of good health (the maintenance of well-being or wellness, quality of life) through nutrition andthe primary (and secondary) prevention of nutrition-related illness in the population. Public health nutri-tion is built on a foundation of basic and appliedsciences, operates in a public health context, and usesthe skills and knowledge of epidemiology and healthpromotion. The World Health Organization (WHO)defines health as a state of complete mental, physicaland social well-being, and not merely the absence ofdisease or infirmity. Public health is defined as the col-lective action taken by society to protect and promotethe health of entire populations. Alternatively, it canbe defined as the art and science of preventing disease,promoting health and prolonging life through theorganized efforts of society. Epidemiology provides arigorous set of methods to study disease occurrence inhuman populations.

Public healthThe approach to public health may be summarized asbeing either broad or narrow (Table 1.1).

The narrow approachThe narrow approach focuses on disease preventionand cost containment, with health defined as theabsence of disease. The underlying theory is that theway in which individuals live their lives (what they eat,what they do, whether they smoke or drink or engagein risky behavior) is the main cause of disease, and thatthe motivation to change behavior is based on reduc-ing risk at an individual level. The evidence base comesfrom clinical and molecular epidemiology; research is

undertaken that identifies differences in risk factors,and on the basis of that information, advice is givento the public that if they change their behavior they will reduce their risk of developing the disease (can-cer or heart disease, etc.). This approach links an indi-vidual’s own behavior to risk of disease. The burdenof prevention and health promotion lies with the indi-vidual and it is seen as their responsibility to addresstheir risk behavior. The approach is aimed at iden-tifying immediate and obvious problems now andaddressing them now. The disadvantage of the narrowapproach is that it may miss fundamental threatswithin society that may be outside the individual’s con-trol (basic and underlying causes such as the widersocioeconomic factors, education and access to services,environmental factors, and the overarching values insociety).

The broad approachThe broad approach defines health as more than theabsence of disease. It considers well-being in terms ofmental and physical health and also includes a senseof having some control over your life. The approachlinks public health science with policy: the action andstructures agreed by society aimed at improving andmaintaining health. The underlying theoretical modelis sociocultural; it focuses on the wider environmentand seeks to understand the factors that enable indi-viduals to make healthy choices, or inhibit them. Themotivating concern is about addressing the underlyingsociostructural factors such as poverty, global issuesand structures at a local, regional, national and inter-national level that affect health. The evidence base fora broad approach comes from epidemiology as well as other approaches more suitable to exploring thesociostructural context. The broad approach takes amore long-term view of causes and solutions, addressing

4 Public health nutrition

Table 1.1 Different approaches to public health

Characteristics Broad Narrow

Major public health activities Link public health science with policy Cost-containment, disease preventionPlace of epidemiology Balanced by other methods Clinical and molecular epidemiologyAdvantages Long term, global ShortDisadvantages Risk of failure because of breadth Miss fundamental threatsDefine health Foundations for health Absence of diseaseUnderlying theory Sociostructural LifestyleMotivating concerns Inequalities, poverty, global Individual risks

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structural issues in society that make it more difficult for individuals to make optimal choices. Thedisadvantage of a broad approach is that because theapproach is so broad it may never address the key rate-limiting steps in a timely manner.

The broad public health approach has been taken upand developed by UNICEF into a conceptual model.The UNICEF model is now widely used, at least inresearch and development in developing countries1

(this term is used in the sense of gross domestic prod-uct, rather than social and cultural development, andis not meant to imply a hierarchy or judgment aboutbetter or worse than a developed country) (see Figure1.1). This conceptual model acknowledges that whilethe immediate causes of undernutrition may be a lackof food, often coupled with a high burden of infection,the provision of adequate education and health care hasan important impact on health. The provision of theseunderlying factors is determined by basic causes suchas the resources that are available in a society, and deci-sions about how these resources will be used. The modelacknowledges that dealing only with the immediatecauses will never lead to long-term improvements,which are dependent on the societies’ view as to howresources will be used and distributed in society to max-imize the health and well-being of all members of soci-ety. These arguments do not apply only to developingcountries; how governments prioritize the use of tax-ation is a function of the underlying values of the soci-ety (as expressed through the election of governmentsthat reflect the popular view); for example, the balanceof spending priorities between education, health anddefense, or priorities for agricultural policies that sub-sidize farmers but not manufacturing industry. Policydecisions as to the priorities on spending are complexand reflect a balance of tensions and pressures that oftenpull in different directions. Policy will be discussed inmore detail later in this chapter.

In reality, in most countries there is a recognition thata narrow (individual and immediate cause oriented)approach needs to be balanced with addressing, at leastto some extent, the basic and underlying (broad) causes.Most governments acknowledge that there are differ-ences in health outcomes in different sectors of societyand that state resources should be used to try to redressthese differences. The food supply is regulated in allcountries, even if the regulation is restricted to issues

of food safety. Many of the first efforts in public healthwere about developing regulations to protect the pub-lic against the adulteration of staple foods. It has alwaysbeen recognized that freedom of choice does not oper-ate in a vacuum. Many countries have regulations aboutthe accuracy of information contained in labels. Thereare few countries where the government does not inter-vene in the food supply to some extent, either throughlegislation to recommend the fortification of foods orto subsidize the production of some foods, such as inthe Common Agricultural Policy in Europe and farm-ing subsidies in the USA and elsewhere.

In developing a public health perspective it is impor-tant to balance the narrow with the broad. Striking theright balance is difficult and influenced by philosoph-ical and political considerations. As a public healthnutritionist, when trying to solve a local or nationalproblem, it is important that both the narrow andbroader determinants of behavior are considered andthat it is not assumed that knowledge and individualchoice are all that matters.

Recently, the UK Faculty of Public Health has agreedthe key concepts that underpin public health. Thesereiterate to some extent the debate about broad ver-sus narrow approaches to public health (Box 1.1). Thekey issues are a population approach to promoting andprotecting health and well-being. They also highlightthe importance of information.

EpidemiologyNutritional epidemiology underpins Public HealthNutrition. This is covered in Chapter 2. It provides a

An overview of public health nutrition 5

Box 1.1 Concepts that underpin public health

• Surveillance and assessment of the population’s health and well-being

• Promoting and protecting the population’s health and well-being• Developing quality and risk management within an evaluative

culture• Collaborative working for health• Developing health programs and services and reducing

inequalities• Policy and strategy development and implementation• Working with and for communities• Strategic leadership for health• Research and development• Ethically managing self, people and resources

Reproduced with permission from the UK Faculty of Public Health.1The preferred terminology for developed and developing countriesis North and South, or low, medium and higher income groups.

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scientific basis for the development of the evidenceupon which public health action can be implemented.It also provides guidance on the approaches as to thebest way to evaluate and monitor the effectiveness ofprograms designed to improve health. Epidemiologyis the only setting in which it is possible to ask ques-tions about what factors affect processes in the wholepopulation. The questions that are asked in epidemi-ological studies need to emerge from metabolic andclinical research; it is important to have some sense ofthe underlying mechanisms and processes involved inthe way the body seeks to maintain optimal function.It is also essential to understand that the biologicalprocesses that maintain functional capacity in humansdo so in a wider context. As mentioned above, epi-demiology is not the only source of information essen-tial to a public health perspective.

Health promotionHealth promotion is defined as any process that enables individuals or communities to increase con-trol over the determinants of their health. The OttawaCharter for health promotion (www.who.int/hpr/archive/docs/Ottawa.html) outlines an internationallyaccepted framework for health promotion that includesfive approaches:

• building healthy public policy

• creating supportive environments

• developing the personal skills of the public and thepractitioners

• reorienting health services

• strengthening community action.

Figure 1.2 summarizes Beattie’s model of health pro-motion. This model further highlights the implicationsof the different underlying philosophical basis ofpublic health discussed above. The two axes of the levelat which promotion operates (individual to group/society) and the approach (authoritative to negotiated)highlight the range of options available. Often a rangeof approaches will be used. The key point is to use theapproach that is going to be most effective and sus-tainable. In order to be effective, it is important thatthe strategy to be used has been shown to be effectivein the target group, and that it addresses the mostimportant constraints or rate-limiting steps, be theyknowledge, attitudes, access or intentions. Under-standing what the rate-limiting step is requires anunderstanding of the balance of factors that affect why

people eat what they eat (see Chapter 8). In some cir-cumstances, a legislative approach, which requires noaction at the individual level, may be the most effec-tive way to achieve the desired health gain. A simpleexample is the decision to fortify flour in the USA withfolic acid (see Chapter 17).

Nutbeam and Harris (1999) have summarized thetheoretical models that underpin a health promotionapproach. It is beyond the scope of this chapter toreview all the models and theories described, and theyare covered in more details in Chapters 5 and 6. Themain point to emphasize here is that at whatever levelone operates, there is a theoretical model that has beendeveloped and should be considered as a basis for orga-nizing the planning of work. A summary of modelsrelevant for the different levels at which health pro-motion works is shown in Table 1.2.

A health promotion planning and evaluation cyclehas been described and involves seven steps:

• problem definition

• solution generation

• resource mobilization

• implementation

• impact assessment

• immediate outcome assessment

• outcome assessment.

For all but the last step in the cycle, theories have been developed as to how to perform each step most

6 Public health nutrition

Authoritative

Health persuasion

Indi

vidu

al Group

Legislative action

Personal counseling

Community development

Negotiated

Figure 1.2 A model for health promotion. Reproduced from Beattie(1981) with permission from Thomson Publishing.

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effectively: to identify targets for intervention; to clar-ify how and when change can be achieved in targets,and how to achieve organizational change and raisecommunity awareness; to provide benchmarksagainst which actual can be compared with ideal pro-grams; and to define outcomes and measurements foruse in evaluation. The precede–proceed model isanother way that has been used to encapsulate the stepsin a health promotion cycle and this will be describedin more detail in Chapter 6. These ideas have beentaken and used as a basis for the development of thepublic health nutrition cycle, which is described inmore detail later in this chapter.

1.4 What are the key public healthproblems?

The chapters in the latter part of this book cover indetail the public health problems that have the great-est public health impact. Here, the aim is to give a broad overview of the overall balance of global nutrition-related health problems, and to highlight, inparticular, the double burden of both overnutritionand undernutrition that many transitional countriessuffer (Figures 1.3–1.6, Table 1.3; http://www.who.int/whr/previous/en/). Data are presented in two ways,which are important to distinguish; Figures 1.3 and 1.4present the proportion of deaths attributable to eachmajor cause, whereas Figure 1.5 and Table 1.3 show the

absolute numbers of deaths or disease burden. Froma public health perspective the total burden of diseasegives a sense of the demands placed on the health ser-vices and infrastructure. Figure 1.3 and 1.4 show theburden of infectious diseases in developing countriescompared with developed countries; Table 1.3 showsthe high burden of human immunodeficiency virus(HIV) and acquired immunodeficiency syndrome(AIDS) in sub-Saharan Africa. Although cancer, as apercentage of overall deaths, is lower in developingthan developed countries, in absolute terms (Figure1.4) more people die of cancer in developing countries.In Africa and south-east Asia (Figure 1.5) the burdenof communicable diseases is high, compared withEurope; in south-east Asia the burden of noncom-municable diseases is nearly as high as communicablediseases and is also higher than in Europe. The higherburden of cancer in developing countries may be afunction of both a higher underlying incidence andpoorer case finding and treatment (owing to limitedaccess to health facilities). The impact of HIV on over-all mortality and life expectancy is illustrated in Figure 1.6, which shows that in a number of Africancountries life expectancy has actually fallen since thelate 1980s, after a steady rise from the 1950s to 1985.

In addition to the burden of death and disability theburden of chronic undernutrition is heavy in manydeveloping countries. It is a stark figure, but 14 000children die every day from malnutrition-related

An overview of public health nutrition 7

Table 1.2 Summary of models relevant for the different levels at which health promotion works (from Nutbeam and Harris, 1999)

Area of change Theories or models

Theories that explain health behavior change by focusing on the individual Health belief modelTheory of reasoned actionTranstheoretical (stages of change) modelSocial learning theory

Theories that explain change in communities and community action for health Community mobilization: Social planningSocial action

Diffusion of innovation

Theories that guide the use of communication strategies for change to promote health Communication for behavior changeSocial marketing

Models that explain changes in organizations and the creation of health-supportive Theories of organizational changeorganizational practices Models of intersectoral action

Models that explain the development and implementation of healthy public policy Ecological framework for policy developmentDeterminants of policy makingIndicators of health promotion policy

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causes. Among those who survive, the effects ongrowth and development are profound and long-lasting. A quarter of all babies born in south Asia weighless than 2500 g at birth (UNICEF, http://www.unicef.org/statis/2001). In India (44%) and Africa (29%)many children are underweight, while the proportion

of the adult population becoming obese is also rising.Food insecurity continues to be a major problem for many people around the world, and not just indeveloping countries (see http://www.euro.who.int/Nutrition for European data and http://www.nlm.nih.gov/pubs/cbm/nutritionsummit.html#51 for US

8 Public health nutrition

50

45

40

35

30

25

20

15

10

5

0

Developed

Developing

Infectious andparasitic diseases

Circulatory Cancers Respiratory Peri andneonatal

Maternal Other

Figure 1.3 Percentage distribution of causes of death. Reproduced with permission from the WHO. (http://www.who.int/whr/previous/en/).

500

400

300

200

100

0

Developed

Developing

Lung Stomach Colorectal Liver Breast Esophagus Mouth Cervix

Figure 1.4 Burden (number per 1000) of cancer in developed and developing countries (women). Reproduced with permission from the WHO.(http://www.who.int/whr/previous/en/).

01 9/7/04 14:21 Page 8

An overview of public health nutrition 9

50000

100000

150000

200000

250000

300000

350000

400000

0

Communicable

Noncommunicable

Africa The Americas Eastern Mediterranean Europe SE Asia

Total

Figure 1.5 Burden of disease in diability-adjusted life-years by WHO Region. Reproduced with permission from the United Nations PopulationDivision. (http://www.who.int/whr/previous/en/).

40

45

50

55

60

65

35

Uganda

1950–55 1955–60 1960–65 1965–70 1970–75 1975–80 1980–85 1985–90 1990–95 1995–00

Botswana

South AfricaZambiaZimbabwe

Life

exp

ecta

ncy

at b

irth

(ye

ars)

Figure 1.6 Changes in life expectancy in selected African countries with high HIV prevalence, 1950–2000. Reproduced with permission from theUnited Nations Population Division.

01 9/7/04 14:21 Page 9

data). The Food and Agriculture Organization (FAO)provides a great deal of information about the nutri-tion situation in most countries (http://www.fao.org/es/esn/nutrition/profiles_en.stm). More details aboutthe burden of undernutrition are covered in Chapter 10.

The double burden of problems of communicable and noncommunicable diseases, related to malnutrition(overnutrition and undernutrition) in the widest sense, was extensively described by Popkin (2002), who summarized the stages of the health, nutritional and

demographic transitions (Figure 1.7). Many countries inthe developing world have subpopulations in differentstages of these transitions, which makes national data dif-ficult to interpret. The complexity also places a particu-lar burden on health services with limited resources.

1.5 Food and nutrition policy

Nutbeam and Harris (1999) highlight that a key areafor achieving change is to understand where policiescome from, so that they may be influenced to addressa particular problem. Policies develop in a dynamicway that is influenced by many factors, one of whichis the scientific evidence (Figure 1.8). Although an indi-vidual public health nutritionist may feel that it is out-side the scope of his or her capacity or job to be ableto influence policy, it is important to have a sense ofwhat factors and forces influence policy. One of theaims of his chapter and book is to give a sense of whereindividual public health nutritionists fit into the grandscheme of things, and that there is actually a bigger pic-ture. This does not mean becoming a lobbyist andinvolved in policy, but to recognize that policies aredeveloped that influence the priorities in society that

10 Public health nutrition

Highfertility/mortality

Reduced mortality,changing age structure

Focus on family planning,infectious disease control

Focus on faminealleviation/prevention

Reduced fertility,aging

Focus on healthy agingspatial redistribution

Demographic transition

High prevalence ofinfectious disease

Receding pestilence, poorenvironment conditions

Chronic diseasespredominate

Epidemiological transition

High prevalence ofundernutrition

Receding famine

Focus on medical intervention, policyinitiatives, behavioral change

Nutrition transition

Diet-related noncommunicablediseases predominate

Figure 1.7 The stages of demographic epidemiological and nutrition transitions in public health nutrition. Reproduced from Popkin (2002) withpermission from The Nutrition Society.

Table 1.3 Leading causes of mortality in sub-SaharanAfrica, 1999

Rank % of total

1 HIV/AIDS 20.62 Acute lower respiratory infections 10.33 Malaria 9.14 Diarrheal diseases 7.35 Perinatal conditions 5.96 Measles 4.97 Tuberculosis 3.48 Cerebrovascular disease 3.29 Ischemic heart disease 3.0

10 Maternal conditions 2.4

Reproduced with permission from the WHO.

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affect the work of public health nutritionists and theircapacity to do their job. It is important to separate outthe process and principles of gathering evidence, andthe subsequent judgment that arises from that evidenceas to what to do or not do about what the evidenceimplies for health.

There are several key players in the development ofpolicy:

• policy holders (usually government politicians)

• policy influencers (lobby groups representing vestedinterests)

• the public

• the media.

The key determinants of policy development are:

• the social climate

• identifiable parties that influence policy

• what the interested parties will gain from the policy

• the ability of those interested parties to make theirvoices heard.

A policy about a particular issue may or may notdevelop because the social climate is not right, thereare competing interests or priorities, or the case has notbeen properly organized to justify the policy. In sim-ple terms, politicians, who make policy, need to see thatif they develop a policy it will achieve what they wantand in a way that will give them the credit (or thatworks). In public health nutrition this means that tomove policy in a way that we believe is desirable forimproved health requires:

• that the climate is right for action around improvingnutrition

• that the profession has its act together and can beeffective in presenting its case

• that when asked it can deliver.

Without policy level commitment, it will be difficultto achieve change. It has been easier to gain support forpolicies around ensuring that the food supply is safe,and today most countries follow internationally agreedrecommendations, mainly summarized in Codex Alimentaris. Policies about what to eat to maximizehealth are more complex than policies to ensure safety. Moreover, there is considerable debate amongst stakeholders and a wider range of vested interests thatcontribute to this debate, making politicians less likelyto support nutrition policies related to health. Withoutpolicies that define goals and targets it is often difficultto mobilize support for action.

Food and nutrition policyThere is lack of clarity about the differences, and drivers for, food compared with nutrition policies.Food policy is concerned about how the food is grownand made available to consumers. It is mostly drivenby concerns about agricultural practices and food production, manufacture and distribution. Nutritionpolicy is driven by a consideration of the impact of thefood supply on health. A great deal more is writtenabout food than about nutrition policy. From a pub-lic health nutrition perspective it should be clear thatthe primary question to be asked when considering pol-icy issues is: “Will it make any difference to improvinghealth, particularly in those with the greatest burden ofpoor health, usually the poorest in society?”

Advocacy and evidence-based policyIt is relevant to discuss briefly and to be able to dis-tinguish between advocacy and evidence-based policy.Advocacy may be defined as the active support of anaction or a cause and therefore an advocate is some-one who upholds or defends that action or cause.Advocacy for a policy or action is usually based on amix of values, beliefs and judgments that the courseof action or policy is the right thing to do. The extentto which it is supported by evidence may depend onthe underlying beliefs of the advocate. It is importantthat a clear distinction is drawn as to where the evi-dence stops and where judgments based on other fac-tors start. The decisions that are made in society andfrom which policies and action arise do not do so in

An overview of public health nutrition 11

Retailers andtrade associations

Judgment aboutmeaning of evidence

Scientific evidenceSocial

Economic

Political

Producer groups

Consumer groups

Policy

Figure 1.8 Influences on the development of policy.

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a vacuum, and even if something appears to be obvi-ous and important, this does not mean that it will besupported and implemented.

1.6 The public health nutrition cycle

Public Health Nutrition is about solving problems. Apublic health nutrition (PHN) cycle has been devel-oped to help to achieve this aim (Figure 1.9). This cyclehas been designed to identify the key steps required todevelop a logical approach to the best way to go aboutsolving problems. At each step in the cycle it is impor-tant not to lose sight of the purpose of the efforts andactivity. Individuals or society should not be asked tochange unless there is good evidence that that changewill be beneficial. Producers and retailers should notbe asked to change the food supply if that change isnot going to improve health and well-being. The gov-ernment should not be asked to develop policies andprograms of work that will not benefit the health ofthe population. Programs of work should certainly notbe recommended that increase inequalities within asociety. In other words, whatever is done needs to havethe most benefit for the most people in the mostefficient way possible. This may involve a combinationof approaches that combine a broad and narrowapproach to health. Ideology should not be allowed tohinder doing what is best.

The PHN cycle resembles a generic policy cycle. Sev-eral international organizations and governments usethe “Triple A” (AAA: assessment, analysis and action)planning cycle (e.g. UNICEF and the South AfricanDepartment of Health).

The Triple A cycle has a number of steps:

1. Assessment: situation analysis; identify problems andselect opportunities for improvement (Where are wenow?)

2. Define the problem operationally (Where do wewant to go?); goals, indicators and objectives.

3. Identify who needs to work on the problem.4. Analyze and study the problem to identify major

causes.5. Develop solutions and action for quality improve-

ment (How will we get there?)6. Implement and evaluate quality improvement

efforts (How do we know when we arrive?)

The PHN cycle is used here to encapsulate an iter-ative, continuous process that starts from an identifi-cation of the public health problems in a population(be it local, national or regional level) and leads to a program of work that is designed to solve the problem. Progress through each step in the cycleshould be evidence based. This includes an evidence-based approach to target setting, program developmentand evaluation. This cycle provides a helpful guidethrough the related but various aspects of public healthnutrition. Sections 1.7–1.13 describe the seven stepsinvolved in the PHN cycle.

1.7 Step 1: Identify key nutrition-relatedproblem

The purpose of public health nutrition is to solve problems. Therefore, one should start by checking what the key nutrition-related problems are within the relevant area of work or country. The followingquestions should be asked before proceeding toaction.

What are the big public health problems in your country/region?Consider how to answer this question. What infor-mation is needed? Is this information available at therequired level?

12 Public health nutrition

1: Identify key nutrition- related problem

2: Set goal

3: Define objectives for goal

4: Create quantitative targets

5: Develop program

7: Evaluate program

6: Implement program

Figure 1.9 Public health nutrition (PHN) cycle.

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Measuring health and quality of life, mortalityand morbidity, incidence and prevalenceInternational agencies produce a great deal of data thatcan be used to give some indication of the burden ofpoor health in a country. These data are generally freelyavailable on the world wide web. Routine data havebeen most widely available for overall mortality, orbroad groupings of causes of mortality, for most coun-tries. These estimates, which are compiled centrally, arebased on locally collected data and caution must beexercised in drawing conclusions from such data. Ide-ally, estimates of health burden should be derived usingdata from high-quality, purpose-specific surveys.Routine data on morbidity are much less readily avail-able than data on mortality. If one is interested in a spe-cific cause of illness (morbidity) or death, in somecountries there will only be limited data from whichto assess whether it really is a public health problem.Incidence data give an indication of new cases emerg-ing over a particular time-frame, whereas prevalenceestimates are a function of the underlying incidenceand the duration of the illness. For many chronic dis-eases the estimates of the incidence and prevalence ofmortality will be adequate. For infectious diseases witha short duration, incidence data will be required.

In some countries when a person dies a death cer-tificate, with underlying causes of death, must be signedby medical practitioner. However, in most developingcountries, particularly in remote areas, when a person

dies very often the underlying cause of death is notrecorded by a medical practitioner and therefore maynot be noted. It is important when comparing coun-tries to be aware that differences may be attributed todifferences in the way data are obtained. Always checkthe assumptions before using routinely collected data.

The WHO in its World Health report in 2002 usedhealthy life expectancy (HALE) as a summary measureof the level of health (www.who.int/whr/en). Althoughthere have been several similar composite measures of health in the past, the universal use of HALE – calculated centrally by means of standard methodologyusing internally consistent estimates of levels ofhealth – is a major advance. HALE is designed to be sen-sitive to changes over time and differences betweencountries in the overall health situation. Nevertheless,HALE based on self-reported health status informationmay not always be comparable across countries, owingto differences in survey instruments and methods, dif-ferences in expectations and norms for health, and cul-tural differences in reporting health.

In 2003 the WHO launched the Surveillance of RiskFactors related to noncommunicable diseases (www.int/mediacentre/factsheets/2003/fs273/en/). This listsall available data for eight risk factors: tobacco andalcohol use, patterns of physical activity, low fruit/ vegetable intake, obesity (body mass index), bloodpressure, cholesterol and diabetes (blood glucose), bro-ken down by age groups and gender for all memberstates. The data are available on a compact disk, whichincludes details of the study populations and methodsused to gather the data for each country. Appendix 3of the report lists the data available by country. Of the46 countries listed in Africa none has data on all eightrisk factors: South Africa and Seychelles have infor-mation on seven risk factors, and only Nigeria andCameroon have data on diet. In Europe data on alleight risk factors are available for 10 out of the 51 coun-tries. In the Americas data for all eight risk factors areavailable for Brazil, Canada, Chile, the USA andUruguay. India is the only country in south-east Asiathat has data on all eight risk factors. Data are pre-sented with a measure of the uncertainty of the esti-mates for each member state.

Specific groups affected: age, socioeconomicgroup, geographical region, ethnic groupNational data may mask regional, local or within-household variation. If the burden of poor health falls

An overview of public health nutrition 13

1: Identify key nutrition- related problem

2: Set goal

3: Define objectives for goal

4: Create quantitative targets

5: Develop program

7: Evaluate program

6: Implement program

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only on a subsector of a society it is important to knowbecause this may influence the approach to solving thatproblem. Data are rarely available in sufficient detail(and with power) to be certain about exactly whichsubgroups are most at risk.

Evidence-based review of link betweennutrition and the problemIf one believes that there is a problem, the next stageis to check whether there is any evidence that linksnutrition to that problem. This requires a systematicreview of all available evidence and a critical appraisalof the studies. From a public health perspective the aimof this review is to identify nutrition risk factors forwhich the evidence is sufficiently strong and consistentto suggest a casual relationship and therefore justifiesaction. This review should also identify whether therisk is in all groups, or only in specific subgroups, eitherbecause of specific nutritional factors that only oper-ate in that group, or because there are other basic orunderlying differences that may confound or interactwith nutrition.

It is a good idea to check whether government orsome other agencies have already reviewed the evi-dence and made some specific recommendations about changes in diet and activity. Even if the nutri-tionist’s review does not agree with these recom-mendations, it is important to know what has beenrecommended.

Developing critical appraisal skills is an essential partof developing a scientific approach to evidence-basedpublic health nutrition, or any other aspect of research.The checklist in Box 1.2 may be useful to begin with.

Are the nutrition risk factors identifiedrelevant to the target population?Does the research identify levels of consumptionthat may be harmful or beneficial? Can the riskestimates be translated into consumptionlevels?Often, the epidemiological study will present an esti-mate of the risk associated with one level of con-sumption compared with another. This is known as arelative risk of, for example, consumption in the high-est third of intake compared with the lowest third ofintake. It is not always presented in absolute terms. Forexample, the risk of colon cancer may be 0.5 in thosein the highest third of vegetable consumption com-pared with those in the lowest third, but this does not

indicate how much vegetable consumption there is ineach third. What is more helpful is a measure of thepopulation attributable risk; this gives a sense of thelikely impact on health if the population changed theirexposure from the lowest to the highest third of intake.The public health impact also depends on how com-mon the health outcome is: if it is common a smallreduction in risk will affect many people; if it is rela-tively uncommon, even a large relative risk will haveonly a small impact on the population burden of ill-health. Ideally, the targets for intervention should bethose exposures that have the biggest effect on health,and on health problems that place the biggest burdenon the target society.

What is the level of consumption in the targetpopulation?If individual country level data are not available fromeither routine surveillance or specific studies, a crudeestimate of average intake can be made from food balance sheet data, produced for all countries by theFAO. The FAO data are crude in that they are a mea-sure of the gross movement of food moving into andout of a country divided by the population. Both thenumerator and the denominator may be inaccurate in

14 Public health nutrition

Box 1.2

• Are the study aims clear and precise in terms of the questionbeing asked?

• Have they described the methods used to:– assess main exposure measure (e.g. weight, food intake

energy intake, attitudes)– assess main outcome measure– assess other variables?

• Have they told you anything about the validity of the measuresused?– information bias– social desirability bias– relevant time-frame.

• Have they described how they derived the sample?– sampling frame– response rate– selection procedure.

• Have they described interview or data collection standardization?• Have they presented the data (tables) in a clear way?• In their discussion have they been objective about the strengths

and weaknesses of their study design?– Have they thought about the impact of what went wrong in

the way they did their study?– Be very skeptical if the authors claim that they did a perfect

study: no such study exists.• Do their conclusions reflect the results presented?

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many countries. These data will give an estimate thatmay be useful, but will not give data about variationwithin a country or for individual levels of consump-tion. Where more detailed individual-level data areavailable, the concern will be as to whether these dataare collected from a representative sample of the tar-get population. If the epidemiology suggests that a par-ticular group of people is at risk, are the data availablerelevant for that at-risk group?

Is consumption within the range that suggestspossibility for beneficial change?If the level of consumption in the target population isalready above the level considered beneficial, then thereis no need for a program to try to improve consump-tion. It may be that at a national level consumptionappears adequate, or at least availability may seem ade-quate, but that the specific target group of interest doesnot achieve the national average. If the target group isbelow the desired level (from the epidemiological evi-dence) it is important to ask why. Is the supply rate lim-iting or is it some other aspect of the sociostructuralenvironment?

Is it plausible that level of consumption couldchange from the current level to the levelsuggested to convey benefit?In public health terms the estimates of risk need to betranslated into levels of consumption. If, for example, thelevel of consumption associated with a 50% reductionin risk was 10 servings per day, and the average daily con-sumption in your target population was one serving perday, is it realistic to expect a 10-fold increase in con-sumption? It may be helpful to look at trends in intakeand assess whether, and by how much, they have changedover the past 10 years. If intake has been relatively flat,and particularly if there have been many campaignsaimed at increasing intake, it is unlikely that big changescan be achieved. However, if a change of one serving aday could lead to a 5% reduction in risk, and if the risk (outcome) affects many people, then this level ofchange may still be very worthwhile trying to achieve. Itis important to be realistic and to consider thecost–benefit of the effort required to achieve the desiredchange in the diet and ultimately the health outcome.

Theoretical models of relevanceAt this stage it may help to begin to think about whatthe major constraints to change might be. The relevant

theories to consider at this stage may relate to indi-vidual beliefs about the proposed intervention, socialnorms, or issues of institutional or societal organiza-tional practices. If the evidence suggests fundamentalchanges in dietary practices in society, it is importantto consider whether the social, cultural and politicalenvironment is likely to be amenable to the changesthat appear to be required.

1.8 Step 2: Set goals and broad aims

Unless there are clear goals and broad aims it will notbe possible to measure the impact of any programsaimed at improving health. It should be clear that theaims of public health nutrition programs are toimprove nutrition-related health outcomes. The suc-cess of programs against this quantitatively definedbackground of work should be judged. No matter howprograms may appear to be delivered, the key measureof impact is a measurable change in health outcome.

These goals inform and direct government policy atthe highest level. These are the broad statements thatpoliticians sign up to and use to argue for fiscal sup-port and political leverage to achieve them. They needto be clear and concise and integrated into the overallhealth and other relevant policies of the government.They set the tone of the approach and highlight thegovernment’s priorities. The way in which these goalsare achieved will vary depending on political ideology,

An overview of public health nutrition 15

1: Identify key nutrition- related problem

2: Set goal

3: Define objectives for goal

4: Create quantitative targets

5: Develop program

7: Evaluate program

6: Implement program

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