Introduction To Human Nutrition

Series ForewordThe early decades of the twentieth century were aperiod of intense research on constituents of foodessential for normal growth and development, andsaw the discovery of most of the vitamins, minerals,amino acids and essential fatty acids. In 1941, a groupof leading physiologists, biochemists and medicalscientists recognized that the emerging discipline ofnutrition needed its own learned society and theNutrition Society was established. Our mission was,and remains, “to advance the scientific study of nutrition and its application to the maintenance of humanand animal health”. The Nutrition Society is the largestlearned society for nutrition in Europe and we haveover 2000 members worldwide. You can find outmore about the Society and how to become a memberby visiting our website at www.nutsoc.org.ukThe ongoing revolution in biology initiated bylarge-scale genome mapping and facilitated by thedevelopment of reliable, simple-to-use molecularbiological tools makes this a very exciting time to beworking in nutrition. We now have the opportunityto obtain a much better understanding of how specific genes interact with nutritional intake and otherlifestyle factors to influence gene expression in individual cells and tissues and, ultimately, affect ourhealth. Knowledge of the polymorphisms in key genescarried by a patient will allow the prescription ofmore effective, and safe, dietary treatments. At thepopulation level, molecular epidemiology is openingup much more incisive approaches to understandingthe role of particular dietary patterns in disease causation. This excitement is reflected in the several scientific meetings that the Nutrition Society, often incollaboration with sister learned societies in Europe,organizes each year. We provide travel grants andother assistance to encourage students and youngresearchers to attend and participate in thesemeetings.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 presentationsmade to the Society. Shortly afterwards, The BritishJournal of Nutrition was established to provide amedium for the publication of primary research onall aspects of human and animal nutrition by scientists from around the world. Recognizing the needs ofstudents and their teachers for authoritative reviewson topical issues in nutrition, the Society began publishing Nutrition Research Reviews in 1988. In 1997,we launched Public Health Nutrition, the first international journal dedicated to this important andgrowing 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 researchmore quickly 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 qualified individuals on our professional registers andby the award of the qualifications Registered PublicHealth Nutritionist (RPHNutr) and Registered Nutritionist (RNutr). Graduates with appropriate degreesbut who do not yet have sufficient postgraduate experience can join our Associate Nutritionist registers.We undertake accreditation of university degree programs in public health nutrition and are developingaccreditation processes for other nutrition degreeprograms.Just as in research, having the best possible tools isan enormous advantage in teaching and learning.This is the reasoning behind the initiative to launchthis series of human nutrition textbooks designed foruse worldwide. This was achieved by successfullylaunching the first series in multiple languages including Spanish, Portuguese and Greek. The Society isdeeply indebted to Professor Mike Gibney and histeam of editors for their tireless work in the last 10years to bring the first edition of this series of textbooks to its successful fruition worldwide. We lookforward to this new edition under the stewardship ofDr Susan Lanham-New in equal measure. Read, learnand enjoy.Professor Ian McDonaldPresident of the Nutrition Society

PrefaceThe Nutrition Society Textbook Series started tenyears ago as an ambitious project to provide undergraduate and graduate students with a comprehensive suite of textbooks to meet their needs in termsof reference material for their studies. By all accountsthe project has been successful and the NutritionSociety Textbook Series have been adapted by all ofthe best academic nutrition units across the globe.The series has been translated into Spanish andPortuguese.This second edition of Introduction to HumanNutrition is an update of the very basic foundationsfor the study of human nutrition. Although little haschanged, all authors have made whatever updates arenecessary and we have made some re-arrangementsof some chapters. The study of human nutrition atuniversities across the globe is rapidly expandingas the role of diet in health becomes more evident.Indeed, the sequencing of the human genome hashighlighted the narrower range of genes controllinghuman biology, emphasising the critically importantrole of the environment including diet in humanhealth. Moreover, we now recognize the importantrole that diet plays in interacting with our genomeboth in utero and in the immediate period of postnatal development.The study of human nutrition needs a solid base inthe physiology and biochemistry of human metabolism and that is the basis of the textbook Nutrition andMetabolism. The present textbook is designed to servetwo needs. Firstly, many will use this book as an introduction to human nutrition and go no further. Students in pharmacy, food science, agriculture and thelike may take introductory modules to human nutrition and leave the subject there but be well informed inthe area. Those who will go on to study human nutrition will find within this textbook an introduction tothe many areas of diet and health that they will go onto study in greater depths using the remaining textbooks in the Nutrition Society series. Besides the basicbiology, students will be introduced to the concept offood policy and to the dual challenges to the globalfood supply, both over and under nutrition.As I write, I am handing over the leadership ofthe Nutrition Society Textbook Series to Dr SusanLanham-New at the University of Surrey who hasagreed to take on this important task for the Society.I would like to thank all those with whom I haveworked with on this project and to wish Sue and hernew team all the very best.Michael J GibneyThe Nutrition Society Textbook Series EditorsOutgoing Editor-in-ChiefProfessor Michael J GibneyUniversity College Dublin, IrelandIncoming Editor-in-ChiefSusan A Lanham-NewUniversity of Surrey, UKAssistant EditorJulie DowsettUniversity College Dublin, IrelandAssistant EditorJennifer NortonThe Nutrition Society, UK

AcknowledgmentsWith grateful appreciation to all those who haveserved on the International Scientific Committee andthe Textbook Editors, without whom this task wouldbe insurmountable and to all the authors who gavetime to make this edition possible. Very special thanksmust go to Mike Gibney and Julie Dowsett, for theireffort and dedication in seeing this textbook of thesecond edition through to publication.

1Introduction to Human Nutrition: A GlobalPerspective on Food and NutritionHester H VorsterKey messages Human nutrition is a complex, multifaceted scientific domainindicating how substances in foods provide essential nourishment for the maintenance of life. To understand, study, research, and practice nutrition, a holisticintegrated approach from molecular to societal level is needed. Optimal, balanced nutrition is a major determinant of health. Itcan be used to promote health and well-being, to prevent illhealth and to treat disease. The study of the structure, chemical and physical characteristics,and physiological and biochemical effects of the more than50 nutrients found in foods underpins the understanding ofnutrition.1.1 Orientation to human nutritionThe major purpose of this series of four textbooks onnutrition is to guide the nutrition student through theexciting journey of discovery of nutrition as a science.As apprentices in nutrition science and practice students will learn how to collect, systemize, and classifyknowledge by reading, experimentation, observation,and reasoning. The road for this journey was mappedout millennia ago. The knowledge that nutrition –what we choose to eat and drink – influences ourhealth, well-being, and quality of life is as old ashuman history. For millions of years the quest forfood has helped to shape human development, theorganization of society and history itself. It has influenced wars, population growth, urban expansion,economic and political theory, religion, science, medicine, and technological development.It was only in the second half of the eighteenthcentury that nutrition started to experience its first 2009 HH Vorster. The hundreds of millions of food- and nutrition-insecure peopleglobally, the coexistence of undernutrition and overnutrition, andinappropriate nutritional behaviors are challenges that face thenutritionist of today. Nutrition practice has a firm and well-developed research andknowledge base. There are, however, many areas where moreinformation is needed to solve global, regional, communal andindividual nutrition problems. The development of ethical norms, standards, and values innutrition research and practice is needed.renaissance with the observation by scientists thatintakes of certain foods, later called nutrients, andeventually other substances not yet classified as nutrients, influence the function of the body, protectagainst disease, restore health, and determine people’sresponse to changes in the environment. Duringthis period, nutrition was studied from a medicalmodel or paradigm by defining the chemical structures and characteristics of nutrients found in foods,their physiological functions, biochemical reactionsand human requirements to prevent, first, deficiencydiseases and, later, also chronic noncommunicablediseases.Since the late 1980s nutrition has experienced asecond renaissance with the growing perception thatthe knowledge gained did not equip mankind to solvethe global problems of food insecurity and malnutrition. The emphasis shifted from the medical or pathological paradigm to a more psychosocial, behavioralone in which nutrition is defined as a basic human

2Introduction to Human Nutritionright, not only essential for human development butalso as an outcome of development.In this first, introductory text, the focus is on principles and essentials of human nut

12. Food and Nutrition: Policy and Regulatory Issues 293. MJ Gibney and A McKevitt. 13. Nutrition Research Methodology 305. JA Martínez and MA Martínez-González. 14. Food Safety: A Public Health Issue of Growing Importance 324. A Reilly, C Tlustos, J O’Connor, and L O’Connor. 15. Food and Nutrition-Related Diseases: The Global Challenge 350