Chapter 7 Vitamins 1. Chapter 7 objectives Know definition, functions and metabolism of fat and water soluble vitamins Discuss requirements, food sources,

Chapter 7 Vitamins 1

Chapter 7 objectives Know definition, functions and metabolism of fat and water soluble vitamins Discuss requirements, food sources, toxicity, and deficiency diseases of fat and water soluble vitamins Know definition, functions and food sources of phytochemicals Discuss vitamin supplementation and functional foods Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 2

Key Concept Vitamins are noncaloric essential nutrients necessary for many metabolic tasks and the prevention of associated deficiency diseases. Pg. 93 Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 3

Dietary Reference Intakes Recommendations for nutrient intake by healthy population groups Based on gender and age – RDA – EAR – AI – UL – Pg.92-93 Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 4

Discovery: Early Observations Discovered while searching for cures for classic diseases – Dr. James Lind and scurvy Sailors dying on long voyages without fresh food Lemons and limes provided, no one became ill British soldiers got the nickname “limeys” Pg.93 Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 5

Discovery: Early Animal Experiments Dr. Frederick Hopkins of Cambridge University – Two groups of rats Group 1: Fed synthetic mix of protein, carbohydrate, fat, mineral salts, and water – All rats died Group 2: Fed same ration but with purified milk – All rats grew normally – Proved that accessory factors are present in natural foods that are essential to life Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 6

Era of Vitamin Discovery Most vitamins were discovered in the first half of the 1900s At first scientists assigned letters of the alphabet to each vitamin – A, C, D, E, K This practice was abandoned in favor of more specific names based on structure and function – Cobalamin, pyridoxine, choline Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 7

Definition of Vitamin It must be a vital, organic substance that is only necessary in extremely small amounts. It cannot be manufactured by the body in sufficient quantities to sustain life, so it must be supplied by diet. Pg.93 Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 8

Function of Vitamins Metabolism: Enzymes and coenzymes B vitamins are part of coenzymes – Coenzymes needed to perform certain functions, such as: Glucose metabolism Protein metabolism Fatty acid metabolism Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 9

Functions of Vitamins, cont’d Tissue structure and protection – Vitamin C Prevention of deficiency diseases – Scurvy (vitamin C) – Beriberi (vitamin B1-thiamin) – Pellagra (vitamin B3-niacin) Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 10

Vitamin Metabolism Fat soluble – Vitamins incorporated with absorbed fat and transported by chylomicrons – Best absorbed when eaten with fat – May be stored for long periods Water soluble – Easily absorbed and transported by the portal circulation – Not stored, so must be eaten on regular basis (exceptions: B12 and B6) Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 12

Key Concepts Certain health problems are related to inadequate or excessive vitamin intake. Vitamins occur in a wide variety of foods that are packaged with the energy- and tissue-building macronutrients (carbohydrate, fat, and protein). The body uses vitamins to make coenzymes required for some enzymes to function. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 13

Fat-Soluble Vitamins: Vitamin A (Retinol) Functions * – Vision – Tissue strength and immunity – Growth Requirements – Food forms and units of measure – Body storage Deficiency disease: Xerophthalmia Toxicity symptoms Food sources Stability Pg.95 Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 15

Vitamin D (Cholecalciferol) Functions* – Absorption of calcium and phosphorus – Bone mineralization Requirements Deficiency disease: Rickets and osteoporosis Toxicity symptoms Food sources Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 17

Vitamin E (Tocopherol) Functions * – Antioxidant function prevents cell damage from free radicals – Relation to selenium metabolism Requirements Deficiency disease: Hemolytic anemia Toxicity symptoms Food sources Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 20

Vitamin K Functions – Blood clotting – Bone development Requirements Deficiency disease: Uncommon Toxicity symptoms : not observed Food sources Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 23

Key Concepts Certain health problems are related to inadequate or excessive vitamin intake. Vitamins occur in a wide variety of foods that are packaged with the energy- and tissue-building macronutrients (carbohydrate, fat, and protein). The body uses vitamins to make coenzymes required for some enzymes to function. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 26

Water-Soluble Vitamins: Vitamin C (Ascorbic Acid) Functions – Connective tissue – General body metabolism – Antioxidant function Requirements Deficiency disease: Scurvy Toxicity symptoms Food sources Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 27

Thiamin (Vitamin B1) Functions – Gastrointestinal system – Nervous system – Cardiovascular system Requirements Deficiency disease: Beriberi Toxicity symptoms Food sources : enriched grains, beef (pg.106) Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 30

Riboflavin (Vitamin B2) Functions – Energy production – Tissue protein building Requirements Deficiency disease Toxicity symptoms Food sources Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 32

Niacin ( B-3 ) Functions – Energy metabolism – DNA repair Requirements Deficiency disease: Pellagra Toxicity symptoms Food sources Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 34

Vitamin B-6 (Pyridoxine) Functions – Protein metabolism – Neurotransmitter Requirements vary with protein intake Deficiency disease Toxicity symptoms Food sources Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 36

Folate Functions – Converted to tetrahydrofolate, which aids in: DNA synthesis Regulation of blood homocysteine levels Requirements Deficiency diseases: Megaloblastic anemia, Neural tube defects Toxicity symptoms Food sources: chicken liver pg.111 table 7- 11 Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 38

Cobalamin (Vitamin B-12) Functions – Regulation of blood homocysteine levels – Heme synthesis – Nervous system functioning Requirements Deficiency disease: Pernicious anemia Toxicity symptoms Food sources Stability Derived from cobalt 40

Pantothenic Acid pg.113 Functions – Acetyl coenzyme A Needed to extract energy from all macronutrients Requirements Deficiency disease: Unlikely Toxicity symptoms Food sources : found in all animal & plant cells Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 43

Biotin Functions – Coenzyme for carboxylases Requirements Deficiency disease: No natural deficiency known Toxicity symptoms Food sources : liver, egg yolk… Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 44

Choline ( pg.115 )  Data insufficient to determine its essentiality  Associated with the B-complex vitamins  Functions ▪ Structural integrity of cell membranes ▪ Neurotransmission  Requirements  Deficiency disease: Liver damage  Toxicity symptoms  Food sources :milk,eggs,liver  Stability Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 45

Phytochemicals Bioactive molecules with health benefits Act as antioxidants or hormones Some researchers believe there are more than 25,000 phytochemicals, many of which have yet to be identified. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 48

Phytochemicals, cont’d Functions – Link between intake and chronic diseases – Synergistic action Recommended intake Food sources – Seven colors with corresponding phytochemical Lycopene, zeaxanthin, anthocyanin, beta-carotene, flavonoids, glucosinolate, allyl sulfides Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 49

Vitamin Supplementation Ongoing debate Biochemical individuality – Life cycle needs Pregnancy and lactation : separate recommendations Infancy : vitamin K, vitamin D Children and adolescents : may require supplementation during growth cycles Aging : due to decreased food intake Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 51

Vitamin Supplementation, cont’d ( pg.119 ) Lifestyle Oral contraceptive use : decrease in B vitamins Restricted diets : nutritional deficiencies Exercise programs: may require supplementation Smoking : decreases body’s vitamin C pool Alcohol : may interfere with absorption of B-complex vitamins Caffeine : diuretic effect flushing out water soluble vitamins more quickly than can be absorbed – Disease : in cases of disease, malnutrition, debilitation etc… Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 56

Vitamin Supplementation, cont’d Megadoses – Toxic effects – “Artificially induced” deficiencies Supplementation principles Functional foods : any food or food ingredient that may provide a health benefit beyond it’s basic nutritional value ex. Tea with added ginger may help with nausea. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 57

Summary Vitamins are food substances required in very small amounts. Body cannot make vitamins, but a well-balanced and varied diet usually supplies sufficient intake. Fat-soluble vitamins are A, D, E, K. Water-soluble vitamins are C and B- complex. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 59

Summary, cont’d Possibility of toxicity is increased for fat- soluble vitamins compared with water- soluble vitamins. Water-soluble vitamins C and pyridoxine in megadoses can be harmful. Phytochemicals are found in whole and unrefined plant foods. Nutrition supplementation is a controversial subject. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 60

Chapter 7 Vitamins 1. Chapter 7 objectives Know definition, functions and metabolism of fat and water soluble vitamins Discuss requirements, food sources,

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Chapter 7 Vitamins 1. Chapter 7 objectives Know definition, functions and metabolism of fat and water soluble vitamins Discuss requirements, food sources,

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