Human nutrition: A health perspective

416 Pages·2003·6.03 MB·English

by  Barasi M.

H U M A N
N U T R I T I O N
A health perspective
second Edition
Mary E. Barasi
BA, BSc, MSc, R. Nutr.
Principal Lecturer in Nutrition,
University of Wales Institute, Cardiff, UK
Illustrations by Megan Morris
Hodder Arnold
A MEMBER OF THE HODDER HEADLINE GROUP
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First published in Great Britain in 2003 by
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ISBN-10: 0340810254
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CONTENTS
Preface v
List of tables vii
List of figures ix
PART ONE THE STUDY OF NUTRITION AND FOOD HABITS 1
Chapter 1 What is nutrition? 3
Chapter 2 What are the influences on eating habits? 18
Chapter 3 Basics of a healthy diet 36
PART TWO THE NUTRIENTS IN FOOD AND THEIR ROLE
IN HEALTH 55
Chapter 4 Proteins 57
Chapter 5 Fats 75
Chapter 6 Carbohydrates 99
Chapter 7 Energy needs 123
Chapter 8 Energy balance 137
Chapter 9 Vitamins 161
Chapter 10 Minerals, electrolytes and fluid 194
PART THREE THE APPLICATION OF NUTRITIONAL
KNOWLEDGE 229
Chapter 11 Pregnancy and lactation 231
Chapter 12 Infants, children and adolescents 251
iii
❚CONTENTS
Chapter 13 Adults and the elderly population 279
Chapter 14 Diet and coronary heart disease 304
Chapter 15 Diet and cancer 324
Chapter 16 Challenges to nutritional status 338
Chapter 17 Optimizing nutrition 364
Chapter 18 Public health nutrition and health promotion 380
Index 397
iv
PREFACE
The need for a second edition of this book stems their impact in nutrition, with research out-
from the continuing rapid changes occurring comes identifying genetic variants that explain
in our understanding of nutrition. A number some of the recognized differences in the way
of these developments can be identified here. individuals respond to nutrients or exhibit
Advances have taken place in the way that increased susceptibility to nutritional disorders.
information is collected and reviewed and the There is a great deal to be discovered in this
concept of an evidence base informing practice field. At some point in the future, we will
has become established. Research findings from understand much more about the way that
many studies can be subjected to reviews, using genes and nutrients interact.
an approach that should be both systematic and The moves towards healthy eating in the last
clear in its methodology. In this way, it is increas- two decades of the twentieth century led to recog-
ingly possible to provide some answers to impor- nitionthat food and nutrition can have positive
tant questions, on the basis of a body of research health benefits. From this has developed a con-
evidence that has been thoroughly analysed and cept of optimal nutrition, wherein food or nutri-
combined with data from similar studies to pro- ents can be actively used to promote health, in
duce quantitative outcomes. This approach of ways that are additional to their nutritional role.
systematic review strengthens the conclusions This has generated new developments within
that are made, and provides a sound basis for the food industry to produce functional or smart
policy or practice to be developed. The Cochrane foods that aim to address these demands. At
Database contains information relating to clini- present, there is a lack of sound evidence about
cal systematic reviews and is a prime example of the mechanisms of action or the benefits in
the application of this methodology. In the humans for some of these components. Conse-
future, all practice should be evidence based, and quently, the amounts required to be consumed
patients and consumers should expect this. for optimal benefit are also unknown, and more
A technological advance that has sometimes research in this area is needed.
worked counter to the concept of an evidence The importance of nutrition as part of public
base has been the widespread use of the Internet, health is now recognized at Government level.
with the proliferation of web-based resources. The Food Standards Agency (FSA) has been
These can provide almost instant access to good established since 2001 to take the lead in the
quality information through online databases UK. The Nutrition Strategy Framework* identi-
and access to scientific publications and rep- fies a number of objectives to improve both
utable web sites, often with extensive links to knowledge and practical aspects of nutrition
related information. However, there is also the throughout society. In order to achieve these,
opportunity for much unscientific and uncon- practical guidance on nutritional issues will be
trolled information to be presented, and this needed at various levels in society and will
may be confusing, inaccurate, misleading and require informed educators. Traditionally, health
potentially dangerous. For users of such infor- professionals have been responsible for health-
mation, there is a real need to have some basic related issues, including nutrition. Those with the
nutrition knowledge to enable them to discern greatest responsibility are dietitians and nutri-
truth from fiction. tionists, yet doctors and nurses may be the people
One of the most exciting developments at who are most readily accessible to the general
the beginning of the new millennium has been population. It has been recognized that all health
the human genome project, with mapping professionals need nutritional knowledge at some
of human DNA. This reflects the enormous
advances that have occurred in molecular biol-
*Food Standards Agency 2000:Your food – farm to fork.
ogy in recent years. These are already having London: FSA.
v
❚PREFACE
level. This, in turn, needs to be disseminated to a new section on the need for fluids. The final
others working within communities who can help section of the book considers more applied
to further disseminate the messages about dietary aspects of nutrition during the normal stages of
improvements. the life cycle, in situations that challenge nutri-
This new edition of the book retains the tional status as well as the relationship between
structure of the first edition, but has been sub- nutrition and major diseases. Optimal nutrition,
stantially updated and extended. A new chapter and nutrition policy and health promotion are
has been added to include optimal nutrition and considered in this section.
smart or functional foods. The author is grateful to all those who have
The book takes a practical approach, involv- helped in the development of the book, includ-
ing the reader in thinking about their own nutri- ing colleagues and students who offer endless
tion, in order to understand better why people eat challenges with interesting and stimulating
as they do, and the difficulties that others may questions. I would also like to thank Megan
have in changing their food intake. There are Morris for her imaginative contribution in the
activities and study questions within each chapter illustrations throughout the text. The produc-
that are intended to stimulate further thought and tion of the book has been efficiently managed
practise problem-solving. References for further by Georgina Bentliff and Heather Smith from
reading are provided at the end of each chapter the publishers.
for those who wish to pursue further study. Thank you also to my family for their sup-
Sections in the book include an introduction port throughout the work on this edition.
to the study of nutrition and the foundations of
healthy eating. This is followed by a section on Mary Barasi
the macronutrients and micronutrients, and Cardiff
includes a consideration of energy balance and 2003
vi
LIST OF TABLES
1.1 Different levels of studying nutrition 5
2.1 Factors influencing the availability of foods 28
2.2 Factors influencing the acceptability of foods 28
2.3 Core, secondary and peripheral foods 31
3.1 Dietary reference values for fat and carbohydrate for adults, as a percentage of daily
total food energy intake (excluding alcohol) 44
3.2 Nutritional details of the five groups in the UK National Food Guide (the Balance of
Good Health) 49
4.1 The amino acids classified according to the nature of their side-chains 60
4.2 Sources of protein 61
4.3 Amino acids that may become indispensable under certain circumstances 63
4.4 The use of complementary foods to make up for limiting amino acids in some
plant foods 69
4.5 Dietary reference values for protein for adults 70
5.1 Classification of fatty acids by saturation, chain length and family 78
5.2 Fat contents of selected foods per 100g, per average serving portion and as per cent
energy from fat 82
5.3 Trends in total fat and energy intakes, per person per day, showing mean population
figures and intakes in the highest and lowest income groups studied by the National
Food Survey 83
5.4 Percentage of energy from the main groups of fatty acids 83
5.5 Sources of fat and fatty acids in the British diet 84
5.6 Summary of fate of fat digestion products 88
5.7 Typical compositions of lipoprotein particles 88
6.1 Non-starch polysaccharide content of some common foods, showing soluble and
insoluble fractions 106
6.2 Classification of starch according to digestibility 108
6.3 Food groups contributing to total and non-milk extrinsic sugars intakes 118
7.1 The energy conversion factors used in the current UK food composition tables 125
7.2 Percentage of energy from carbohydrate, protein and fat in selected foods 126
7.3 Energy yields obtained from the oxidation of different substrates 129
7.4 The effect on energy yield of different metabolic mixtures and respiratory quotient 129
7.5 Physical activity ratios for calculation of energy expenditure 134
7.6 Estimated average requirements for energy for adults in megajoules per day
(Calories/ day) 135
8.1 Action levels for weight management based on waist circumference 146
8.2 Medical and other consequences of obesity 153
10.1 Average amounts of minerals found in the adult human body 194
10.2 Average values for daily turnover of body water in a temperate climate 222
10.3 Average caffeine (in milligrams per average serving) for some beverages 223
10.4 The water content of some foods (as a percentage) 224
11.1 Guidelines on weight gain in pregnancy 236
11.2 Summary of dietary reference values for pregnancy 238
11.3 Possible indicators of nutritional vulnerability in pregnancy 241
11.4 Dietary reference values for lactation 247
12.1 Reference nutrient intakes for selected nutrients for infants 254
vii
❚LIST OF TABLES
12.2 The estimated average requirement for energy for children up to the age of
12 months 255
12.3 Suggested food groups to be included in the diet at 6–9 months and 12 months 261
12.4 Sources of iron, vitamin C and vitamin D suitable for weaning 262
12.5 Dietary reference values for children from 4 to 18 years 267
12.6 General recommendations on fat and carbohydrates 268
12.7 Contributions of the main macronutrient groups to total energy intake for young
people aged 4 to 18 269
12.8 Minimum nutritional standards for school meals 271
12.9 Summary of Caroline Walker Trust Nutritional Guidelines for School Meals 272
13.1 Types of foods eaten by the highest and lowest income groups studied by the
National Food Survey 2000 290
13.2 ‘Value for money’ of foods bought by high-income and low-income groups 290
13.3 Cost of common snack foods, in pence, to supply 420kJ (100 Calories) 291
13.4 Factors contributing to poor food intake in the elderly 297
13.5 Percentages of elderly subjects with nutrient intakes from food sources below the LRNI 299
13.6 Prevalence of suboptimal indices for nutrients in elderly subjects 300
15.1 Summary of stages in cancer development 326
15.2 Some proposed links between dietary componentsand cancers 331
15.3 Summary of diet and health recommendations 335
16.1 Grouping of some commonly eaten foods according to glycaemic index 355
17.1 Functional foods in sports nutrition 374
18.1 Summary of chronic diseases and other health problems with possible dietary links 383
18.2 Population goals for nutrients, foods and lifestyle factors, consistent with the
prevention of major public health problems in Europe 384
18.3 Model for stages of change 389
viii
LIST OF FIGURES
1.1 A pyramid represents the contents of the diet and can be used as the basis of a
food guide 7
1.2 Measurement of skinfold for assessment of body fat content 12
1.3 Summary of the main methods of anthropometry 13
2.1 Physiological factors controlling hunger and food intake 19
2.2 Habit influences eating behaviour 22
2.3 Psychological need as a trigger to eating 23
2.4 Sensory appeal as a trigger for eating 24
2.5 Why do we eat? 25
2.6 Some of the main components of a person’s food habits 26
3.1 The stages of development of a clinical deficiency 41
3.2 The normal distribution curve of nutrient requirements in a population and levels
used for setting dietary recommendations 42
3.3 Distribution of riboflavin intakes in a population of 12-year-old boys 45
3.4 The USA Food Guide pyramid: a guide to daily food choices 47
3.5 The UK National Food Guide: the Balance of Good Health 48
3.6 Example of a day’s food intake and the numbers of servings from the National
Food Guide 50
4.1 Origin of human dietary protein 58
4.2 Digestion of proteins 62
4.3 Summary of amino acid metabolism 64
4.4 Summary of uses of protein 66
4.5 Components of nitrogen balance 68
4.6 Example of cases of protein deficiency 71
5.1 Spatial configuration of saturated, cisandtransunsaturated fatty acids 78
5.2 Chemical structure of cholesterol 81
5.3 Sources of visible and invisible fats 81
5.4 Why do we eat fat? 85
5.5 Digestion and absorption of fats 87
5.6 Exogenous lipid transport 89
5.7 Endogenous lipid transport and metabolism 90
5.8 The role of adipose tissue in metabolism 92
5.9 Aspects of insulin resistance 94
6.1 Structural formulae for three simple sugars 100
6.2 The condensation of two molecules of glucose to form maltose 101
6.3 Structures of starch and cellulose 103
6.4 The relationship of non-starch polysaccharides to other sources of carbohydrate 105
6.5 Digestion of carbohydrates 109
6.6 Rise in blood glucose after eating, and the calculation of glycaemic index 110
6.7 Metabolism of carbohydrates 111
6.8 Why do we need carbohydrates in the diet? 112
6.9 Development of dental caries and the role of diet 115
6.10 Summary of the effects of non-starch polysaccharides in the digestive tract 119
7.1 The bomb calorimeter 124
7.2 The components of energy output 128
7.3 Factors affecting basal metabolic rate 131
ix