Vitamin and mineral requirements in human nutrition

Recommended By: K V Ramani
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Foreword xiii

Acknowledgements xvii

1. Concepts, definitions and approaches used to define nutritional
needs and recommendations 1
1.1 Introduction 1
1.2 Definition of terms 2
1.2.1 Estimated average requirement 2
1.2.2 Recommended nutrient intake 2
1.2.3 Apparently healthy 3
1.2.4 Protective nutrient intake 3
1.2.5 Upper tolerable nutrient intake level 4
1.2.6 Nutrient excess 4
1.2.7 Use of nutrient intake recommendations in population
assessment 5
1.3 Approaches used in estimating nutrient intakes for optimal
health 6
1.3.1 The clinical approach 8
1.3.2 Nutrient balance 8
1.3.3 Functional responses 9
1.3.4 Optimal intake 10
1.4 Conclusions 12
References 14

2. Vitamin A 17
2.1 Role of vitamin A in human metabolic processes 17
2.1.1 Overview of vitamin A metabolism 17
2.1.2 Biochemical mechanisms for vitamin A functions 19
2.2 Populations at risk for, and consequences of, vitamin A
deficiency 20
2.2.1 Definition of vitamin A deficiency 20
2.2.2 Geographic distribution and magnitude 20
2.2.3 Age and sex 21
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VITAMIN AND MINERAL REQUIREMENTS IN HUMAN NUTRITION
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2.2.4 Risk factors 22
2.2.5 Morbidity and mortality 23
2.3 Units of expression 24
2.4 Sources and supply patterns of vitamin A 27
2.4.1 Dietary sources 27
2.4.2 Dietary intake and patterns 27
2.4.3 World and regional supply and patterns 27
2.5 Indicators of vitamin A deficiency 29
2.5.1 Clinical indicators of vitamin A deficiency 29
2.5.2 Subclinical indicators of vitamin A deficiency 30
2.6 Evidence used for making recommendations 31
2.6.1 Infants and children 32
2.6.2 Adults 33
2.6.3 Pregnant women 33
2.6.4 Lactating women 34
2.6.5 Elderly 35
2.7 Recommendations for vitamin A requirements 35
2.8 Toxicity 36
2.9 Recommendations for future research 37
References 37

3. Vitamin D 45
3.1 Role of vitamin D in human metabolic processes 45
3.1.1 Overview of vitamin D metabolism 45
3.1.2 Calcium homeostasis 46
3.2 Populations at risk for vitamin D deficiency 48
3.2.1 Infants 48
3.2.2 Adolescents 48
3.2.3 Elderly 48
3.2.4 Pregnant and lactating women 49
3.3 Evidence used for estimating recommended intakes 51
3.3.1 Lack of accuracy in estimating dietary intake and skin
synthesis 51
3.3.2 Use of plasma 25-OH-D as a measure of vitamin D
status 51
3.4 Recommended intakes for vitamin D 53
3.5 Toxicity 54
3.6 Recommendations for future research 55
References 55
4. Calcium 59
4.1 Introduction 59
4.2 Chemistry and distribution of calcium 60
4.3 Biological role of calcium 61
4.4 Determinants of calcium balance 62
4.4.1 Calcium intake 62
4.4.2 Calcium absorption 62
4.4.3 Urinary calcium 65
4.4.4 Insensible losses 66
4.5 Criteria for assessing calcium requirements and
recommended nutrient intakes 66
4.5.1 Methodology 66
4.5.2 Populations at risk for calcium deficiency 69
4.6 Recommendations for calcium requirements 69
4.6.1 Infants 69
4.6.2 Children 70
4.6.3 Adolescents 71
4.6.4 Adults 72
4.6.5 Menopausal women 72
4.6.6 Ageing adults 73
4.6.7 Pregnant women 73
4.6.8 Lactating women 73
4.7 Upper limits 74
4.8 Comparisons with other recommendations 74
4.9 Ethnic and environmental variations in the prevalence of
osteoporosis 75
4.9.1 Ethnicity 76
4.9.2 Geography 76
4.9.3 Culture and diet 77
4.9.4 The calcium paradox 78
4.10 Nutritional factors affecting calcium requirement 78
4.10.1 Sodium 78
4.10.2 Protein 79
4.10.3 Vitamin D 81
4.10.4 Implications 81
4.11 Conclusions 83
4.12 Recommendations for future research 85
References 85

5. Vitamin E 94
5.1 Role of vitamin E in human metabolic processes 94
5.2 Populations at risk for vitamin E deficiency 97
5.3 Dietary sources and possible limitations to vitamin E supply 100
5.4 Evidence used for estimating recommended intakes 101
5.5 Toxicity 103
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VITAMIN AND MINERAL REQUIREMENTS IN HUMAN NUTRITION
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5.6 Recommendations for future research 103
References 104

6. Vitamin K 108
6.1 Introduction 108
6.2 Biological role of vitamin K 108
6.3 Overview of vitamin K metabolism 110
6.3.1 Absorption and transport 110
6.3.2 Tissue stores and distribution 111
6.3.3 Bioactivity 112
6.3.4 Excretion 112
6.4 Populations at risk for vitamin K deficiency 113
6.4.1 Vitamin K deficiency bleeding in infants 113
6.4.2 Vitamin K prophylaxis in infants 114
6.4.3 Vitamin K deficiency in adults 115
6.5 Sources of vitamin K 115
6.5.1 Dietary sources 115
6.5.2 Bioavailability of vitamin K from foods 116
6.5.3 Importance of intestinal bacterial synthesis as
a source of vitamin K 117
6.6 Information relevant to the derivation of recommended
vitamin K intakes 117
6.6.1 Assessment of vitamin K status 117
6.6.2 Dietary intakes in infants and their adequacy 118
6.6.3 Factors of relevance to classical vitamin K deficiency
bleeding 119
6.6.4 Factors of relevance to late vitamin K deficiency
bleeding 120
6.6.5 Dietary intakes in older infants, children, and adults
and their adequacy 120
6.7 Recommendations for vitamin K intakes 122
6.7.1 Infants 0–6 months 122
6.7.2 Infants (7–12 months), children, and adults 125
6.8 Toxicity 126
6.9 Recommendations for future research 126
References 126
7. Vitamin C 130
7.1 Introduction 130
7.2 Role of vitamin C in human metabolic processes 130
7.2.1 Background biochemistry 130
7.2.2 Enzymatic functions 130
7.2.3 Miscellaneous functions 131
7.3 Consequences of vitamin C deficiency 131
7.4 Populations at risk for vitamin C deficiency 132
7.5 Dietary sources of vitamin C and limitations to vitamin C
supply 134
7.6 Evidence used to derive recommended intakes of vitamin C 135
7.6.1 Adults 135
7.6.2 Pregnant and lactating women 137
7.6.3 Children 137
7.6.4 Elderly 138
7.6.5 Smokers 138
7.7 Recommended nutrient intakes for vitamin C 138
7.8 Toxicity 139
7.9 Recommendations for future research 139
References 139

8. Dietary antioxidants 145
8.1 Nutrients with an antioxidant role 145
8.2 The need for biological antioxidants 145
8.3 Pro-oxidant activity of biological antioxidants 147
8.4 Nutrients associated with endogenous antioxidant mechanisms 150
8.5 Nutrients with radical-quenching properties 151
8.5.1 Vitamin E 151
8.5.2 Vitamin C 153
8.5.3 b-Carotene and other carotenoids 154
8.6 A requirement for antioxidant nutrients 156
8.7 Recommendations for future research 158
References 158

9. Thiamine, riboflavin, niacin, vitamin B6, pantothenic acid,
and biotin 164
9.1 Introduction 164
9.2 Thiamine 165
9.2.1 Background 165
9.2.2 Biochemical indicators 166
9.2.3 Factors affecting requirements 167
9.2.4 Evidence used to derive recommended intakes 167
9.2.5 Recommended nutrient intakes for thiamine 168
9.3 Riboflavin 169
9.3.1 Background 169
9.3.2 Biochemical indicators 170
9.3.3 Factors affecting requirements 171
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9.3.4 Evidence used to derive recommended intakes 171
9.3.5 Recommended nutrient intakes for riboflavin 172
9.4 Niacin 173
9.4.1 Background 173
9.4.2 Biochemical indicators 174
9.4.3 Factors affecting requirements 174
9.4.4 Evidence used to derive recommended intakes 175
9.4.5 Recommended nutrient intakes for niacin 175
9.5 Vitamin B6 175
9.5.1 Background 175
9.5.2 Biochemical indicators 177
9.5.3 Factors affecting requirements 178
9.5.4 Evidence used to derive recommended intakes 178
9.5.5 Recommended nutrient intakes for vitamin B6 179
9.6 Pantothenate 180
9.6.1 Background 180
9.6.2 Biochemical indicators 180
9.6.3 Factors affecting requirements 181
9.6.4 Evidence used to derive recommended intakes 181
9.6.5 Recommended nutrient intakes for pantothenic acid 182
9.7 Biotin 182
9.7.1 Background 182
9.7.2 Biochemical indicators 183
9.7.3 Evidence used to derive recommended intakes 183
9.7.4 Recommended nutrient intakes for biotin 184
9.8 General considerations for B-complex vitamins 184
9.8.1 Notes on suggested recommendations 184
9.8.2 Dietary sources of B-complex vitamins 185
9.9 Recommendations for future research 185
References 186

10. Selenium 194
10.1 Role of selenium in human metabolic processes 194
10.2 Selenium deficiency 196
10.2.1 Non-endemic deficiencies of selenium 196
10.2.2 Keshan disease 197
10.2.3 Kaschin-Beck disease 198
10.2.4 Selenium status and susceptibility to infection 198
10.2.5 Selenium and thyroid hormones 200
10.3 The influence of diet on selenium status 200
10.4 Absorption and bioavailability 204
10.5 Criteria for assessing selenium requirements 204
10.6 Recommended selenium intakes 206
10.6.1 Adults 206
10.6.2 Infants 206
10.6.3 Pregnant and lactating women 208
10.7 Upper limits 209
10.8 Comparison with other estimates 209
10.9 Recommendations for future research 210
References 211

11. Magnesium 217
11.1 Tissue distribution and biological role of magnesium 217
11.2 Populations at risk for, and consequences of,
magnesium deficiency 218
11.3 Dietary sources, absorption, and excretion of magnesium 218
11.4 Criteria for assessing magnesium requirements and allowances 220
11.5 Recommended intakes for magnesium 222
11.6 Upper limits 225
11.7 Comparison with other estimates 225
11.8 Recommendations for future research 225
References 226
12. Zinc 230
12.1 Role of zinc in human metabolic processes 230
12.2 Zinc metabolism and homeostasis 231
12.3 Dietary sources and bioavailability of zinc 232
12.4 Populations at risk for zinc deficiency 234
12.5 Evidence used to estimate zinc requirements 235
12.5.1 Infants, children, and adolescents 236
12.5.2 Pregnant women 238
12.5.3 Lactating women 238
12.5.4 Elderly 239
12.6 Interindividual variations in zinc requirements and
recommended nutrient intakes 239
12.7 Upper limits 240
12.8 Adequacy of zinc intakes in relation to requirement estimates 241
12.9 Recommendations for future research 242
References 243

13. Iron 246
13.1 Role of iron in human metabolic processes 246
13.2 Iron metabolism and absorption 246
13.2.1 Basal iron losses 246
13.2.2 Requirements for growth 247
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13.2.3 Menstrual iron losses 249
13.2.4 Iron absorption 250
13.2.5 Inhibition of iron absorption 252
13.2.6 Enhancement of iron absorption 254
13.2.7 Iron absorption from meals 255
13.2.8 Iron absorption from the whole diet 255
13.2.9 Iron balance and regulation of iron absorption 256
13.3 Iron deficiency 258
13.3.1 Populations at risk for iron deficiency 258
13.3.2 Indicators of iron deficiency 260
13.3.3 Causes of iron deficiency 261
13.3.4 Prevalence of iron deficiency 262
13.3.5 Effects of iron deficiency 263
13.4 Iron requirements during pregnancy and lactation 264
13.5 Iron supplementation and fortification 267
13.6 Evidence used for estimating recommended nutrient intakes 268
13.7 Recommendations for iron intakes 271
13.8 Recommendations for future research 272
References 272

14. Vitamin B12 279
14.1 Role of vitamin B12 in human metabolic processes 279
14.2 Dietary sources and availability 279
14.3 Absorption 280
14.4 Populations at risk for, and consequences of, vitamin B12
deficiency 280
14.4.1 Vegetarians 280
14.4.2 Pernicious anaemia 281
14.4.3 Atrophic gastritis 281
14.5 Vitamin B12 interaction with folate or folic acid 282
14.6 Criteria for assessing vitamin B12 status 283
14.7 Recommendations for vitamin B12 intakes 284
14.7.1 Infants 285
14.7.2 Children 285
14.7.3 Adults 285
14.7.4 Pregnant women 286
14.7.5 Lactating women 286
14.8 Upper limits 286
14.9 Recommendations for future research 287
References 287

15. Folate and folic acid 289
15.1 Role of folate and folic acid in human metabolic processes 289
15.2 Populations at risk for folate deficiency 294
15.3 Dietary sources of folate 294
15.4 Recommended nutrient intakes for folate 295
15.5 Differences in bioavailability of folic acid and food folate:
implications for the recommended intakes 297
15.6 Considerations in viewing recommended intakes for folate 297
15.6.1 Neural tube defects 297
15.6.2 Cardiovascular disease 298
15.6.3 Colorectal cancer 298
15.7 Upper limits 299
15.8 Recommendations for future research 299
References 300

16. Iodine 303
16.1 Role of iodine in human metabolic processes 303
16.2 Populations at risk for iodine deficiency 304
16.3 Dietary sources of iodine 305
16.4 Recommended intakes for iodine 306
16.4.1 Infants 307
16.4.2 Children 309
16.4.3 Adults 309
16.4.4 Pregnant women 310
16.5 Upper limits 311
16.5.1 Iodine intake in areas of moderate iodine deficiency 312
16.5.2 Iodine intake in areas of iodine sufficiency 313
16.5.3 Excess iodine intake 314
References 315

17. Food as a source of nutrients 318
17.1 Importance of defining food-based recommendations 318
17.2 Dietary diversification when consuming cereal- and
tuber-based diets 325
17.2.1 Vitamin A 325
17.2.2 Vitamin C 325
17.2.3 Folate 326
17.2.4 Iron and zinc 326
17.3 How to accomplish dietary diversity in practice 327
17.4 Practices which will enhance the success of food-based
approaches 328
17.5 Delineating the role of supplementation and food fortification
for micronutrients which cannot be supplied by food 329
17.5.1 Fortification 330
CONTENTS
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17.5.2 Supplementation 332
17.6 Food-based dietary guidelines 333
17.7 Recommendations for the future 335
17.8 Future research needs 335
References 336

Annex 1: Recommended nutrient intakes – minerals 338
Annex 2: Recommended nutrient intakes – water- and fat-soluble
vitamins 340