211. Biochemistry Of Vitamins

You are here: Home / 211. Biochemistry Of Vitamins

 

211. Biochemistry Of Vitamins

 

 

CATEGORY: Diet Nutrition Supplementation – 500 Courses

COURSE NUMBER: 211

FEES: 555/- INR only

CERTIFICATE VALIDITY: Lifetime

CERTIFICATES DELIVERY: In 48 hours

BOOKS/ MANUALS: Pages

Syllabus

List of Figures page xvii
List of Tables xxi
Preface xxiii
1 The Vitamins 1
1.1 Definition and Nomenclature of the Vitamins 2
1.1.1 Methods of Analysis and Units of Activity 6
1.1.2 Biological Availability 8
1.2 Vitamin Requirements and Reference Intakes 10
1.2.1 Criteria of Vitamin Adequacy and the Stages of
Development of Deficiency 10
1.2.2 Assessment of Vitamin Nutritional Status 12
1.2.3 Determination of Requirements 17
1.2.3.1 Population Studies of Intake 17
1.2.3.2 Depletion/Repletion Studies 18
1.2.3.3 Replacement of Metabolic Losses 18
1.2.3.4 Studies in Patients Maintained on Total
Parenteral Nutrition 19
1.2.4 Reference Intakes of Vitamins 19
1.2.4.1 Adequate Intake 23
1.2.4.2 Reference Intakes for Infants and Children 23
1.2.4.3 Tolerable Upper Levels of Intake 24
1.2.4.4 Reference Intake Figures for Food Labeling 27
2 Vitamin A: Retinoids and Carotenoids 30
2.1 Vitamin A Vitamers and Units of Activity 31
2.1.1 Retinoids 31
2.1.2 Carotenoids 33
2.1.3 International Units and Retinol Equivalents 35
2.2 Absorption and Metabolism of Vitamin A and Carotenoids 35
2.2.1 Absorption and Metabolism of Retinol and Retinoic Acid 35
2.2.1.1 Liver Storage and Release of Retinol 36
2.2.1.2 Metabolism of Retinoic Acid 38
2.2.1.3 Retinoyl Glucuronide and Other Metabolites 39
2.2.2 Absorption and Metabolism of Carotenoids 40
2.2.2.1 Carotene Dioxygenase 41
2.2.2.2 Limited Activity of Carotene Dioxygenase 42
2.2.2.3 The Reaction Specificity of Carotene Dioxygenase 43
2.2.3 Plasma Retinol Binding Protein (RBP) 45
2.2.4 Cellular Retinoid Binding Proteins CRBPs and
CRABPs 47
2.3 Metabolic Functions of Vitamin A 49
2.3.1 Retinol and Retinaldehyde in the Visual Cycle 49
2.3.2 Genomic Actions of Retinoic Acid 54
2.3.2.1 Retinoid Receptors and Response Elements 55
2.3.3 Nongenomic Actions of Retinoids 58
2.3.3.1 Retinoylation of Proteins 58
2.3.3.2 Retinoids in Transmembrane Signaling 60
2.4 Vitamin A Deficiency (Xerophthalmia) 61
2.4.1 Assessment of Vitamin A Nutritional Status 64
2.4.1.1 Plasma Concentrations of Retinol and ß-Carotene 64
2.4.1.2 Plasma Retinol Binding Protein 65
2.4.1.3 The Relative Dose Response (RDR) Test 66
2.4.1.4 Conjunctival Impression Cytology 66
2.5 Vitamin A Requirements and Reference Intakes 66
2.5.1 Toxicity of Vitamin A 68
2.5.1.1 Teratogenicity of Retinoids 70
2.5.2 Pharmacological Uses of Vitamin A, Retinoids,
and Carotenoids 71
2.5.2.1 Retinoids in Cancer Prevention and Treatment 71
2.5.2.2 Retinoids in Dermatology 72
2.5.2.3 Carotene 72
3 Vitamin D 77
3.1 Vitamin D Vitamers, Nomenclature, and Units of Activity 78
3.2 Metabolism of Vitamin D 79
3.2.1 Photosynthesis of Cholecalciferol in the Skin 80
3.2.2 Dietary Vitamin D 82
3.2.3 25-Hydroxylation of Cholecalciferol 83
3.2.4 Calcidiol 1a-Hydroxylase 85
3.2.5 Calcidiol 24-Hydroxylase 85
3.2.6 Inactivation and Excretion of Calcitriol 86
3.2.7 Plasma Vitamin D Binding Protein (Gc-Globulin) 87
3.2.8 Regulation of Vitamin D Metabolism 87
3.2.8.1 Calcitriol 88
3.2.8.2 Parathyroid Hormone 88
3.2.8.3 Calcitonin 88
3.2.8.4 Plasma Concentrations of Calcium and Phosphate 89
3.3 Metabolic Functions of Vitamin D 89
3.3.1 Nuclear Vitamin D Receptors 91
3.3.2 Nongenomic Responses to Vitamin D 92
3.3.3 Stimulation of Intestinal Calcium and Phosphate Absorption 93
3.3.3.1 Induction of Calbindin-D 93
3.3.4 Stimulation of Renal Calcium Reabsorption 94
3.3.5 The Role of Calcitriol in Bone Metabolism 94
3.3.6 Cell Differentiation, Proliferation, and Apoptosis 96
3.3.7 Other Functions of Calcitriol 97
3.3.7.1 Endocrine Glands 98
3.3.7.2 The Immune System 98
3.4 Vitamin D Deficiency – Rickets and Osteomalacia 98
3.4.1 Nonnutritional Rickets and Osteomalacia 99
3.4.2 Vitamin D-Resistant Rickets 100
3.4.3 Osteoporosis 101
3.4.3.1 Glucocorticoid-Induced Osteoporosis 102
3.5 Assessment of Vitamin D Status 103
3.6 Requirements and Reference Intakes 104
3.6.1 Toxicity of Vitamin D 105
3.6.2 Pharmacological Uses of Vitamin D 106
4 Vitamin E: Tocopherols and Tocotrienols 109
4.1 Vitamin E Vitamers and Units of Activity 109
4.2 Metabolism of Vitamin E 113
4.3 Metabolic Functions of Vitamin E 115
4.3.1 Antioxidant Functions of Vitamin E 116
4.3.1.1 Prooxidant Actions of Vitamin E 118
4.3.1.2 Reaction of Tocopherol with Peroxynitrite 119
4.3.2 Nutritional Interactions Between Selenium and Vitamin E 120
4.3.3 Functions of Vitamin E in Cell Signaling 121
4.4 Vitamin E Deficiency 122
4.4.1 Vitamin E Deficiency in Experimental Animals 122
4.4.2 Human Vitamin E Deficiency 125
4.5 Assessment of Vitamin E Nutritional Status 125
4.6 Requirements and Reference Intakes 127
4.6.1 Upper Levels of Intake 128
4.6.2 Pharmacological Uses of Vitamin E 128
4.6.2.1 Vitamin E and Cancer 129
4.6.2.2 Vitamin E and Cardiovascular Disease 129
4.6.2.3 Vitamin E and Cataracts 129
4.6.2.4 Vitamin E and Neurodegenerative Diseases 129
5 Vitamin K 131
5.1 Vitamin K Vitamers 132
5.2 Metabolism of Vitamin K 133
5.2.1 Bacterial Biosynthesis of Menaquinones 135
5.3 The Metabolic Functions of Vitamin K 135
5.3.1 The Vitamin K-Dependent Carboxylase 136
5.3.2 Vitamin K-Dependent Proteins in Blood Clotting 139
5.3.3 Osteocalcin and Matrix Gla Protein 141
5.3.4 Vitamin K-Dependent Proteins in Cell Signaling – Gas6 142
5.4 Vitamin K Deficiency 142
5.4.1 Vitamin K Deficiency Bleeding in Infancy 143
5.5 Assessment of Vitamin K Nutritional Status 143
5.6 Vitamin K Requirements and Reference Intakes 145
5.6.1 Upper Levels of Intake 145
5.6.2 Pharmacological Uses of Vitamin K 146
6 Vitamin B1 – Thiamin 148
6.1 Thiamin Vitamers and Antagonists 148
6.2 Metabolism of Thiamin 150
6.2.1 Biosynthesis of Thiamin 153
6.3 Metabolic Functions of Thiamin 153
6.3.1 Thiamin Diphosphate in the Oxidative Decarboxylation
of Oxoacids 154
6.3.1.1 Regulation of Pyruvate Dehydrogenase Activity 155
6.3.1.2 Thiamin-Responsive Pyruvate Dehydrogenase
Deficiency 156
6.3.1.3 2-Oxoglutarate Dehydrogenase and the ? -Aminobutyric
Acid (GABA) Shunt 156
6.3.1.4 Branched-Chain Oxo-acid Decarboxylase and Maple
SyrupUrine Disease 158
6.3.2 Transketolase 159
6.3.3 The Neuronal Function of Thiamin Triphosphate 159
6.4 Thiamin Deficiency 161
6.4.1 Dry Beriberi 161
6.4.2 Wet Beriberi 162
6.4.3 Acute Pernicious (Fulminating) Beriberi – Shoshin Beriberi 162
6.4.4 The Wernicke–Korsakoff Syndrome 163
6.4.5 Effects of Thiamin Deficiency on Carbohydrate Metabolism 164
6.4.6 Effects of Thiamin Deficiency on Neurotransmitters 165
6.4.6.1 Acetylcholine 165
6.4.6.2 5-Hydroxytryptamine 165
6.4.7 Thiaminases and Thiamin Antagonists 166

6.5 Assessment of Thiamin Nutritional Status 167
6.5.1 Urinary Excretion of Thiamin and Thiochrome 167
6.5.2 Blood Concentration of Thiamin 167
6.5.3 Erythrocyte Transketolase Activation 168
6.6 Thiamin Requirements and Reference Intakes 169
6.6.1 Upper Levels of Thiamin Intake 169
6.6.2 Pharmacological Uses of Thiamin 169
7 Vitamin B2 – Riboflavin 172
7.1 Riboflavin and the Flavin Coenzymes 172
7.2 The Metabolism of Riboflavin 175
7.2.1 Absorption, Tissue Uptake, and Coenzyme Synthesis 175
7.2.2 Riboflavin Binding Protein 177
7.2.3 Riboflavin Homeostasis 178
7.2.4 The Effect of Thyroid Hormones on Riboflavin Metabolism 178
7.2.5 Catabolism and Excretion of Riboflavin 179
7.2.6 Biosynthesis of Riboflavin 181
7.3 Metabolic Functions of Riboflavin 183
7.3.1 The Flavin Coenzymes: FAD and Riboflavin Phosphate 183
7.3.2 Single-Electron-Transferring Flavoproteins 184
7.3.3 Two-Electron-Transferring Flavoprotein Dehydrogenases 185
7.3.4 Nicotinamide Nucleotide Disulfide Oxidoreductases 185
7.3.5 Flavin Oxidases 186
7.3.6 NADPH Oxidase, the Respiratory Burst Oxidase 187
7.3.7 Molybdenum-Containing Flavoprotein Hydroxylases 188
7.3.8 Flavin Mixed-Function Oxidases (Hydroxylases) 189
7.3.9 The Role of Riboflavin in the Cryptochromes 190
7.4 Riboflavin Deficiency 190
7.4.1 Impairment of Lipid Metabolism in Riboflavin Deficiency 191
7.4.2 Resistance to Malaria in Riboflavin Deficiency 192
7.4.3 Secondary Nutrient Deficiencies in Riboflavin Deficiency 193
7.4.4 Iatrogenic Riboflavin Deficiency 194
7.5 Assessment of Riboflavin Nutritional Status 196
7.5.1 Urinary Excretion of Riboflavin 196
7.5.2 Erythrocyte Glutathione Reductase (EGR) Activation
Coefficient 197
7.6 Riboflavin Requirements and Reference Intakes 197
7.7 Pharmacological Uses of Riboflavin 198
8 Niacin 200
8.1 Niacin Vitamers and Nomenclature 201
8.2 Niacin Metabolism 203
8.2.1 Digestion and Absorption 203
8.2.1.1 Unavailable Niacin in Cereals 203
8.2.2 Synthesis of the Nicotinamide Nucleotide Coenzymes 203

8.2.3 Catabolism of NAD(P) 205
8.2.4 Urinary Excretion of Niacin Metabolites 206
8.3 The Synthesis of Nicotinamide Nucleotides from Tryptophan 208
8.3.1 Picolinate Carboxylase and Nonenzymic Cyclization to
Quinolinic Acid 210
8.3.2 Tryptophan Dioxygenase 211
8.3.2.1 Saturation of Tryptophan Dioxygenase with Its
Heme Cofactor 211
8.3.2.2 Induction of Tryptophan Dioxygenase by
Glucocorticoid Hormones 211
8.3.2.3 Induction Tryptophan Dioxygenase by Glucagon 212
8.3.2.4 Repression and Inhibition of Tryptophan Dioxygenase
by Nicotinamide Nucleotides 212
8.3.3 Kynurenine Hydroxylase and Kynureninase 212
8.3.3.1 Kynurenine Hydroxylase 213
8.3.3.2 Kynureninase 213
8.4 Metabolic Functions of Niacin 214
8.4.1 The Redox Function of NAD(P) 214
8.4.1.1 Use of NAD(P) in Enzyme Assays 215
8.4.2 ADP-Ribosyltransferases 215
8.4.3 Poly(ADP-ribose) Polymerases 217
8.4.4 cADP-Ribose and Nicotinic Acid Adenine Dinucleotide
Phosphate (NAADP) 219
8.5 Pellagra – A Disease of Tryptophan and Niacin Deficiency 221
8.5.1 Other Nutrient Deficiencies in the Etiology of Pellagra 222
8.5.2 Possible Pellagragenic Toxins 223
8.5.3 The Pellagragenic Effect of Excess Dietary Leucine 223
8.5.4 Inborn Errors of Tryptophan Metabolism 224
8.5.5 Carcinoid Syndrome 224
8.5.6 Drug-Induced Pellagra 225
8.6 Assessment of Niacin Nutritional Status 225
8.6.1 Tissue and Whole Blood Concentrations of Nicotinamide
Nucleotides 226
8.6.2 Urinary Excretion of N1-Methyl Nicotinamide and Methyl
Pyridone Carboxamide 226
8.7 Niacin Requirements and Reference Intakes 227
8.7.1 Upper Levels of Niacin Intake 228
8.8 Pharmacological Uses of Niacin 229
9 Vitamin B6 232
9.1 Vitamin B6 Vitamers and Nomenclature 233
9.2 Metabolism of Vitamin B6 234
9.2.1 Muscle Pyridoxal Phosphate 236
9.2.2 Biosynthesis of Vitamin B6 236
9.3 Metabolic Functions of Vitamin B6 236
9.3.1 Pyridoxal Phosphate in Amino Acid Metabolism 237
9.3.1.1 a-Decarboxylation of Amino Acids 239

9.3.1.2 Racemization of the Amino Acid Substrate 241
9.3.1.3 Transamination of Amino Acids (Aminotransferase
Reactions) 241
9.3.1.4 Steps in the Transaminase Reaction 242
9.3.1.5 Transamination Reactions of Other Pyridoxal
Phosphate Enzymes 243
9.3.1.6 Transamination and Oxidative Deamination Catalyzed
by Dihydroxyphenylalanine (DOPA) Decarboxylase 243
9.3.1.7 Side-Chain Elimination and Replacement Reactions 244
9.3.2 The Role of Pyridoxal Phosphate in Glycogen Phosphorylase 244
9.3.3 The Role of Pyridoxal Phosphate in Steroid Hormone Action
and Gene Expression 245
9.4 Vitamin B6 Deficiency 246
9.4.1 Enzyme Responses to Vitamin B6 Deficiency 247
9.4.2 Drug-Induced Vitamin B6 Deficiency 249
9.4.3 Vitamin B6 Dependency Syndromes 250
9.5 The Assessment of Vitamin B6 Nutritional Status 250
9.5.1 Plasma Concentrations of Vitamin B6 251
9.5.2 Urinary Excretion of Vitamin B6 and 4-Pyridoxic Acid 251
9.5.3 Coenzyme Saturation of Transaminases 252
9.5.4 The Tryptophan Load Test 252
9.5.4.1 Artifacts in the Tryptophan Load Test Associated with
Increased Tryptophan Dioxygenase Activity 253
9.5.4.2 Estrogens and Apparent Vitamin B6 Nutritional Status 254
9.5.5 The Methionine Load Test 255
9.6 Vitamin B6 Requirements and Reference Intakes 256
9.6.1 Vitamin B6 Requirements Estimated from Metabolic
Turnover 256
9.6.2 Vitamin B6 Requirements Estimated from Depletion/
Repletion Studies 257
9.6.3 Vitamin B6 Requirements of Infants 259
9.6.4 Toxicity of Vitamin B6 259
9.6.4.1 Upper Levels of Vitamin B6 Intake 260
9.7 Pharmacological Uses of Vitamin B6 261
9.7.1 Vitamin B6 and Hyperhomocysteinemia 261
9.7.2 Vitamin B6 and the Premenstrual Syndrome 262
9.7.3 Impaired Glucose Tolerance 262
9.7.4 Vitamin B6 for Prevention of the Complications of
Diabetes Mellitus 263
9.7.5 Vitamin B6 for the Treatment of Depression 264
9.7.6 Antihypertensive Actions of Vitamin B6 264
9.8 Other Carbonyl Catalysts 265
9.8.1 Pyruvoyl Enzymes 266
9.8.2 Pyrroloquinoline Quinone (PQQ) and Tryptophan
Tryptophylquinone (TTQ) 266
9.8.3 Quinone Catalysts in Mammalian Enzymes 268

10 Folate and Other Pterins and Vitamin B12 270
10.1 Folate Vitamers and Dietary Folate Equivalents 271
10.1.1 Dietary Folate Equivalents 271
10.2 Metabolism of Folates 273
10.2.1 Digestion and Absorption of Folates 273
10.2.2 Tissue Uptake and Metabolism of Folate 274
10.2.2.1 Poly-? -glutamylation of Folate 275
10.2.3 Catabolism and Excretion of Folate 276
10.2.4 Biosynthesis of Pterins 276
10.3 Metabolic Functions of Folate 279
10.3.1 Sources of Substituted Folates 279
10.3.1.1 Serine Hydroxymethyltransferase 279
10.3.1.2 Histidine Catabolism 281
10.3.1.3 Other Sources of One-Carbon Substituted Folates 283
10.3.2 Interconversion of Substituted Folates 283
10.3.2.1 Methylene-Tetrahydrofolate Reductase 284
10.3.2.2 Disposal of Surplus One-Carbon Fragments 286
10.3.3 Utilization of One-Carbon Substituted Folates 286
10.3.3.1 Thymidylate Synthetase and Dihydrofolate Reductase 287
10.3.3.2 Dihydrofolate Reductase Inhibitors 288
10.3.3.3 The dUMP Suppression Test 289
10.3.4 The Role of Folate in Methionine Metabolism 289
10.3.4.1 The Methyl Folate TrapHypothesis 291
10.3.4.2 Hyperhomocysteinemia and Cardiovascular Disease 292
10.4 Tetrahydrobiopterin 294
10.4.1 The Role of Tetrahydrobiopterin in Aromatic Amino
Acid Hydroxylases 294
10.4.2 The Role of Tetrahydrobiopterin in Nitric Oxide Synthase 296
10.5 Molybdopterin 297
10.6 Vitamin B12 Vitamers and Nomenclature 298
10.7 Metabolism of Vitamin B12 300
10.7.1 Digestion and Absorption of Vitamin B12 300
10.7.2 Plasma Vitamin B12 Binding Proteins and Tissue Uptake 301
10.7.3 Bacterial Biosynthesis of Vitamin B12 303
10.8 Metabolic Functions of Vitamin B12 303
10.8.1 Methionine Synthetase 304
10.8.2 Methylmalonyl CoA Mutase 305
10.8.3 Leucine Aminomutase 306
10.9 Deficiency of Folic Acid and Vitamin B12 307
10.9.1 Megaloblastic Anemia 308
10.9.2 Pernicious Anemia 308
10.9.3 Neurological Degeneration in Vitamin B12 Deficiency 309
10.9.4 Folate Deficiency and Neural Tube Defects 310
10.9.5 Folate Deficiency and Cancer Risk 311
10.9.6 Drug-Induced Folate Deficiency 312
10.9.7 Drug-Induced Vitamin B12 Deficiency 313

10.10 Assessment of Folate and Vitamin B12 Nutritional Status 313
10.10.1 Plasma and Erythrocyte Concentrations of Folate
and Vitamin B12 314
10.10.2 The Schilling Test for Vitamin B12 Absorption 315
10.10.3 Methylmalonic Aciduria and Methylmalonic Acidemia 316
10.10.4 Histidine Metabolism – the FIGLU Test 316
10.10.5 The dUMP Suppression Test 317
10.11 Folate and Vitamin B12 Requirements and Reference
Intakes 318
10.11.1 Folate Requirements 318
10.11.2 Vitamin B12 Requirements 318
10.11.3 Upper Levels of Folate Intake 319
10.12 Pharmacological Uses of Folate and Vitamin B12 321
11 Biotin (Vitamin H) 324
11.1 Metabolism of Biotin 324
11.1.1 Bacterial Synthesis of Biotin 327
11.1.1.1 The Importance of Intestinal Bacterial Synthesis
of Biotin 329
11.2 The Metabolic Functions of Biotin 329
11.2.1 The Role of Biotin in Carboxylation Reactions 330
11.2.1.1 Acetyl CoA Carboxylase 330
11.2.1.2 Pyruvate Carboxylase 331
11.2.1.3 Propionyl CoA Carboxylase 331
11.2.1.4 Methylcrotonyl CoA Carboxylase 332
11.2.2 Holocarboxylase Synthetase 332
11.2.2.1 Holocarboxylase Synthetase Deficiency 332
11.2.3 Biotinidase 334
11.2.3.1 Biotinidase Deficiency 335
11.2.4 Enzyme Induction by Biotin 335
11.2.5 Biotin in Regulation of the Cell Cycle 336
11.3 Biotin Deficiency 337
11.3.1 Metabolic Consequences of Biotin Deficiency 338
11.3.1.1 Glucose Homeostasis in Biotin Deficiency 338
11.3.1.2 Fatty Liver and Kidney Syndrome in Biotin-Deficient
Chicks 338
11.3.1.3 Cot Death 339
11.3.2 Biotin Deficiency In Pregnancy 340
11.4 Assessment of Biotin Nutritional Status 340
11.5 Biotin Requirements 341
11.6 Avidin 341
12 Pantothenic Acid 345
12.1 Pantothenic Acid Vitamers 345
12.2 Metabolism of Pantothenic Acid 346
12.2.1 The Formation of CoA from Pantothenic Acid 348
12.2.1.1 Metabolic Control of CoA Synthesis 349

12.2.2 Catabolism of CoA 350
12.2.3 The Formation and Turnover of ACP 350
12.2.4 Biosynthesis of Pantothenic Acid 351
12.3 Metabolic Functions of Pantothenic Acid 352
12.4 Pantothenic Acid Deficiency 353
12.4.1 Pantothenic Acid Deficiency in Experimental Animals 353
12.4.2 Human Pantothenic Acid Deficiency – The Burning
Foot Syndrome 354
12.5 Assessment of Pantothenic Acid Nutritional Status 355
12.6 Pantothenic Acid Requirements 355
12.7 Pharmacological Uses of Pantothenic Acid 356
13 Vitamin C (Ascorbic Acid) 357
13.1 Vitamin C Vitamers and Nomenclature 358
13.1.1 Assay of Vitamin C 359
13.2 Metabolism of Vitamin C 359
13.2.1 Intestinal Absorption and Secretion of Vitamin C 361
13.2.2 Tissue Uptake of Vitamin C 361
13.2.3 Oxidation and Reduction of Ascorbate 362
13.2.4 Metabolism and Excretion of Ascorbate 363
13.3 Metabolic Functions of Vitamin C 364
13.3.1 Dopamine ß-Hydroxylase 365
13.3.2 Peptidyl Glycine Hydroxylase (Peptide a-Amidase) 366
13.3.3 2-Oxoglutarate–Linked Iron-Containing Hydroxylases 367
13.3.4 Stimulation of Enzyme Activity by Ascorbate In Vitro 369
13.3.5 The Role of Ascorbate in Iron Absorption and
Metabolism 369
13.3.6 Inhibition of Nitrosamine Formation by Ascorbate 370
13.3.7 Pro- and Antioxidant Roles of Ascorbate 371
13.3.7.1 Reduction of the Vitamin E Radical by Ascorbate 371
13.3.8 Ascorbic Acid in Xenobiotic and Cholesterol Metabolism 371
13.4 Vitamin C Deficiency – Scurvy 372
13.4.1 Anemia in Scurvy 373
13.5 Assessment of Vitamin C Status 374
13.5.1 Urinary Excretion of Vitamin C and Saturation Testing 374
13.5.2 Plasma and Leukocyte Concentrations of Ascorbate 374
13.5.3 Markers of DNA Oxidative Damage 376
13.6 Vitamin C Requirements and Reference Intakes 376
13.6.1 The Minimum Requirement for Vitamin C 376
13.6.2 Requirements Estimated from the Plasma and Leukocyte
Concentrations of Ascorbate 378
13.6.3 Requirements Estimated from Maintenance of the Body
Pool of Ascorbate 378
13.6.4 Higher Recommendations 379
13.6.4.1 The Effect of Smoking on Vitamin C Requirements 380

13.6.5 Safety and Upper Levels of Intake of Vitamin C 380
13.6.5.1 Renal Stones 380
13.6.5.2 False Results in Urine Glucose Testing 381
13.6.5.3 Rebound Scurvy 381
13.6.5.4 Ascorbate and Iron Overload 382
13.7 Pharmacological Uses of Vitamin C 382
13.7.1 Vitamin C in Cancer Prevention and Therapy 382
13.7.2 Vitamin C in Cardiovascular Disease 383
13.7.3 Vitamin C and the Common Cold 383
14 Marginal Compounds and Phytonutrients 385
14.1 Carnitine 385
14.1.1 Biosynthesis and Metabolism of Carnitine 386
14.1.2 The Possible Essentiality of Carnitine 388
14.1.3 Carnitine as an Ergogenic Aid 388
14.2 Choline 389
14.2.1 Biosynthesis and Metabolism of Choline 389
14.2.2 The Possible Essentiality of Choline 391
14.3 Creatine 392
14.4 Inositol 393
14.4.1 Phosphatidylinositol in Transmembrane Signaling 394
14.4.2 The Possible Essentiality of Inositol 394
14.5 Taurine 396
14.5.1 Biosynthesis of Taurine 396
14.5.2 Metabolic Functions of Taurine 398
14.5.2.1 Taurine Conjugation of Bile Acids 398
14.5.2.2 Taurine in the Central Nervous System 398
14.5.2.3 Taurine and Heart Muscle 399
14.5.3 The Possible Essentiality of Taurine 399
14.6 Ubiquinone (Coenzyme Q) 400
14.7 Phytonutrients: Potentially Protective Compounds in
Plant Foods 401
14.7.1 Allyl Sulfur Compounds 401
14.7.2 Flavonoids and Polyphenols 402
14.7.3 Glucosinolates 403
14.7.4 Phytoestrogens 404
Bibliography 409
Index 463

……………………………………………………………………………………………………………………………………………………………………………………………………………………

 

Medifit  Courses Demo Certificate 

48 hours delivery

| International acceptance | Medical based | Job oriented | Lifetime validity | Most economical |

 

555 INR Demo Certificate – 2 months duration

Demo Certificate – 6 months duration

48 hours delivery after fees payment

48 hours delivery after fees payment

 

Medifit 48 hours Delivery

  Get your Certificates delivered by online mode in 48 hours after Fees payment. We try to deliver certificates in 24 hours, but the committed delivery hours are 48. Its,

Pay Today &
get Tomorrow

procedure, only by Medifit.

LIFETIME VALIDITY

Medifit issues Lifetime validity certificates for all Online Courses provided. No need to renew the certificates every 2 or 3 years. All Courses Certificates of Medifit are having Lifetime Validity. No need to renew these certificates every 2 or 3 years.

 

What makes the certificates of Medifit to get it recognized Internationally?

Vast number of students applying for Job in international market of Fitness through Medifits Online Courses Certificates. And most importantly, the Medical standards maintained, helps to acquire jobs internationally. This gives very strong International acceptance to Certificates of Medifit Courses.

 

ABOUT MEDIFIT ACADEMY CERTIFICATION COURSE:

Medifit Education Online Academy is an innovative, digital and engaging education platform that delivers fast track accredited courses and skills development courses instantly online, with no time limits, enabling individuals to study anywhere and anytime. We are proud to offer international standard courses that have helped our students build their careers across the globe.

HOW DO MEDIFIT ONLINE CERTIFICATE COURSES HELP?

Short term Professional Courses International Standards courses Opens Global opportunities Career defining Courses Skill Development Programmes Knowledge in short span Learn at your own pace Certification of Completion Immediate Earning Opportunities Positive Social Impact Optimistic Psychological Benefits Improved Standard of Living Study from anywhere & anytime Very Economical Fees

[/cmsms_text][/cmsms_column][/cmsms_row]