Phytonutrients is divided into three parts. The first deals with the role of plants in the human diet. Part II, representing the major part of the book covers in turn each of the major phytonutrient groups. Chapters include: non-lipid micronutrients, lipids and steroids, carotenoids, phenolics, vitamins C, E, folate/vitamin B12, phytoestrogens, other phytonutrients and minerals, and anti-nutritional factors. The final part of the book covers the methods used to manipulate levels of phytonutrients in the diet, such as fortification, supplementation and the use of genetically modified plants.
Phytonutrients is an essential purchase for nutritionists, food scientists and plant biochemists, particularly those dealing with nutrients from plants, and their use in the human diet.
Table of Contents
Preface xiContributors xii
Abbreviations xv
1 Plant foods and health 1
Judith Buttriss
Introduction 1
Historical changes in the plant content of the human diet 1
Changing composition of dietary constituents in the past 50 years 5
Plants – nutrients and other constituents 6
A summary of the evidence linking plant food intake and health 6
Coronary heart disease and stroke 9
Fruits and vegetables 9
Pulses and nuts 13
Cereals 15
Antioxidant nutrients 17
Other bioactive substances 18
Antioxidant hypothesis 20
Phytosterols and –stanols 20
Conclusions for coronary heart disease and stroke 21
Cancer 21
Fruit and vegetables 21
Legumes and nuts 26
Foods containing fibre 26
Vitamins 26
Other plant-derived substances 28
Conclusions for cancer 28
Type 2 diabetes 29
Age-related macular degeneration and cataract 29
Age-related cognitive decline 30
Chronic obstructive pulmonary disease 31
Osteoporosis and bone health 31
Plant foods and health: overall conclusions 32
Recommendations and current policy on plant food intake 33
Fruit and vegetables 33
Wholegrain foods 35
Current consumption patterns 35
Conclusions 39
Acknowledgement 40
2 Carbohydrates and lipids 52
Andrew Salter and Gregory Tucker
Introduction 52
Major carbohydrates 53
Sugars 54
Polysaccharides 55
Starch 55
Cell wall polymers 58
Biosynthesis of cell wall polymers 60
Cell wall turnover 62
Nutritional benefits of plant carbohydrates 64
Major sources of dietary fibre within the diet and recommended intakes 64
Definition and measurement of dietary fibre 65
Physiological effects of dietary fibre 66
Lipids 68
Synthesis of fatty acids in plants 69
Synthesis of glycerolipids in plants 70
Modification of plant lipids 73
Fatty acid composition of plant foods 76
Vegetables 76
Cereals 77
Fruit 77
Oil seeds 77
Dietary lipids and human health 79
Phytosterols 80
3 Carotenoids 89
Úrsula Flores-Perez and Manuel Rodriguez-Concepcion
Introduction 89
Structure, biosynthesis and function of plant carotenoids 90
Dietary sources and health benefits 93
Absorption and bioavailability of dietary carotenoids 97
Carotenoid type 98
Food matrix 98
Carotenoid metabolism in humans 99
Meeting the dietary demand and consequences for imbalance 101
Acknowledgements 102
4 Polyphenols 110
David Vauzour, Katerina Vafeiadou and Jeremy P. E. Spencer
Introduction 110
Polyphenol structure 110
Phenolic acids and stilbenes 110
Flavonoids 113
Biosynthetic routes within the plant 115
Shikimic precursor and benzoic acid biosynthesis 115
Cinnamic acid biosynthesis 115
Stilbene biosynthesis 119
Flavonoid biosynthesis 119
Major sources within the diet 121
Phenolic acids and stilbenes 121
Flavonoids 121
Flavonols 121
Flavanones 122
Flavanols 123
Flavones 123
Anthocyanins 123
Isoflavones 123
Metabolic fate of dietary polyphenols 124
Gastrointestinal tract metabolism 124
Colonic metabolism 126
Role in human health 127
Flavonoids as classical antioxidants 128
Non-antioxidant activities of fl avonoids 130
Interactions with cell signalling pathways 131
Other potential mechanisms of action 133
Conclusion 133
Summary 134
Acknowledgements 134
5 Vitamins C and E 146
David Gray, John Brameld and Gregory Tucker
Introduction 146
Vitamin C: structure and chemistry 146
Dietary sources of vitamin C 147
Vitamin C: biosynthesis and metabolism in plants 148
Vitamin C functions in plants 152
Vitamin C manipulation in plants 154
Absorption and transport of vitamin C in mammals 155
Vitamin E: structure and chemistry 156
Dietary sources of vitamin E 159
Vitamin E: biosynthetic pathways 159
Roles of tocochromanols in plants 161
Manipulation of tocochromanol concentration 162
Absorption and transport of vitamin E in mammals 164
Antioxidant functions of vitamin E 164
6 Folate 173
Stéphane Ravanel and Fabrice Rébeillé
Introduction 173
One-carbon metabolism 174
Generation and interconversion of C1-units 176
Serine–glycine metabolism 176
Formate activation 176
Histidine catabolism 177
Interconvertion of C1-substituted folates 178
Utilisation of C1-units 179
Methionine synthesis 179
Purine ring formation 179
Formylation of methionyl-tRNA 180
Thymidylate synthesis 180
Pantothenate synthesis 180
Folate synthesis and distribution in plants 181
Biosynthesis of tetrahydrofolate in plants 181
Pterin branch 182
pABA branch 183
Assembly of the pterin, pABA and glutamate moieties 183
Reduction and polyglutamylation 184
Catabolism and salvage pathway 185
Compartmentation and transport of folates 185
Subcellular location of folates 185
Folate transporters 186
Folates distribution in plants 186
Physiology of folate in human health and disease 188
Absorption 188
Transport, storage, catabolism and excretion 189
Metabolic and clinical manifestations of folate deficiency 189
Diagnosis of folate deficiency 190
Folate bioavailability, requirements and food fortification 191
Bioavailability 191
Dietary intake recommendations 192
Dietary sources of folate 192
Food fortification 194
Prospects for plant foods biofortification 195
7 Phytoestrogens 203
Helen Wiseman
Introduction 203
Biosynthesis of phytoestrogens 203
Introduction 203
Isoflavonoids 203
Prenylated flavonoids 205
Stilbenes 205
Lignans 205
Genetic engineering 205
Isoflavonoids 206
Introduction 206
Dietary sources and intakes 206
Metabolism and bioavailability 208
Isoflavonoids and cancer prevention 211
Hormone-dependent cancer prevention by isoflavonoids 211
Oestrogens and risk of breast cancer 213
Oestrogen receptor-mediated events 213
Animal models 215
Mechanisms of anticancer action of isoflavonoids 217
Clinical studies 219
Protection by isoflavonoids against cardiovascular disease 220
Cholesterol-lowering and isoflavonoids 220
Antioxidant action 222
Arterial function 225
Cellular effects 226
Protection by isoflavonoids against osteoporosis, cognitive decline and menopausal symptoms? 226
Osteoporosis 226
Menopausal symptoms and cognitive decline 227
Isoflavonoids: potential risks 228
Lignans 229
Introduction 229
Production of mammalian lignans 230
Cardiovascular disease 230
Breast cancer prevention 230
Prostate cancer prevention 230
Prevention of other types of cancer 231
Other health benefits 231
Prenylflavonoids 231
Stilbenes 233
Miroestrol 235
Deoxybenzoins 235
Coumestans 236
Phytoestrogens and human health: conclusions 236
8 Plant minerals 254
Martin R. Broadley and Philip J. White
Introduction 254
Genetic variation in plant mineral concentration 258
Introduction 258
Between-species genetic variation in plant mineral concentration 258
Within-species genetic variation in plant mineral concentration 259
Iron and zinc 260
Iodine and selenium 263
Calcium and magnesium 264
Copper 266
Has the mineral concentration of crops declined due to breeding for increased yield? 266
Evidence for a decline in mineral concentration of horticultural crops 266
Is there evidence for a decline in mineral concentration of staple crops? 267
A case study on potatoes; a précis of White et al. (2009) 268
Index 278
