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Chapter 7
The Vitamins
Nutrition: Concepts & Controversies, 12e
Sizer/Whitney
Learning Objectives
 List the fat-soluble and water-soluble
vitamins, and describe how solubility affects
the absorption, transport, storage, and
excretion of each type.
 Explain how vitamins and minerals work in
combination to maintain the health of the
bones.
 Name some functions of vitamin D not
associated with the bones.
Learning Objectives
 Define the term antioxidant, and name the
vitamins that act as antioxidants in the
body.
 Discuss the roles of B vitamins in body
tissues, and explain in a general way how B
vitamins assist with energy metabolism.
 Present arguments both for and against
vitamin fortification of foods.
Learning Objectives
 Suggest foods that can help to ensure
adequate vitamin intakes without providing
too many calories.
 Justify this statement: “It is better to get
vitamins from food than from supplements.”
 List some valid reasons why supplements
may be required by some people.
Definition and Classification of
Vitamins
 Vitamin
 Essential, noncaloric, organic
 Role of vitamins
 Vitamin precursors
 Classes
 Absorption
 Roles
Vitamin Names
Characteristics of the Fat-Soluble
and Water-Soluble Vitamins
The Fat-Soluble Vitamins
 A, D, E, and K
 Food sources
 Storage
 Toxicity
 Deficiency
 Roles within the body
Vitamin A
 Precursor
 Beta-carotene
 Active forms in the body
 Retinol
 Retinal
 Retinoic acid
 Food sources
Vitamin A – Roles and Deficiency
 Gene regulation
 Retinoic acid
 Eyesight
 Process of light perception
 Maintenance of healthy cornea
 Rhodopsin molecule
An Eye
Vitamin A – Roles and Deficiency
 Night blindness
 Deficiency
 Xerophthalmia and blindness
 Keratinization
 Deficiency
 Cell differentiation
 Immune function
 Growth
Vitamin A – Deficiency and
Toxicity
 Deficiency
 Worldwide problem
 Blindness
 HIV
 Toxicity
 Symptoms
 food sources
 Liver
Vitamin A – Deficiency and
Toxicity
 Toxicity
 Supplements
 Higher risk groups
 Recommendations
 DRI recommendation based on body weight
 Food sources
 Animal origin
 Liver
 Plant origin
Vitamin A Deficiency and Toxicity
Vitamin A – Snapshot
Beta-Carotene
 Plant-based foods
 Colorful groups
 Macular degeneration
 Dietary antioxidant
 Measuring beta-carotene
 Retinol activity equivalents (RAE)
 Toxicity
 Food sources
Excess Beta-Carotene Symptom:
Discoloration of the Skin
Vitamin D
 Body can synthesize all it needs
 Sunlight
 Transformation
 Liver and kidneys
 Estimated deficiency prevalence
Vitamin D – Roles
 Bone integrity
 Hormone
 Dangers with
deficiency
Vitamin D – Too Little, Too Much
 Deficiency
 Rickets
 Recommendations for prevention
 Osteomalacia
 Recommendations
 Toxicity
 Signs of toxicity
Rickets
Vitamin D
 Ultraviolet B light rays
 Cholesterol
 Sunbathing risks
 Sunscreen
 Exposure times
 Intake
recommendations
 Food sources
Factors Affecting Vitamin D
Synthesis
Vitamin D - Snapshot
Vitamin E
 Roles of vitamin E
 Antioxidant
 Deficiency
 Symptoms
 Toxicity
 Dietary intake vs. supplemental intake
 Recommendations
 Food source
Free-Radical Damage and
Antioxidant Protection
Vitamin E – Snapshot
Vitamin K
 Roles
 Blood clotting
 Bone proteins
 Deficiency
 Toxicity
 Jaundice
 Requirements
 Sources
Vitamin K – Snapshot
The Water-Soluble Vitamins
 Dissolve in water
 Absorption
 Transport
 Excretion
 Sources
 Food
 Supplements
Vitamin C
 Roles
 Connective tissues
 Collagen
 Antioxidant
 Protects iron
 Prooxidant
 Deficiency symptoms
 Scurvy
Scurvy Symptoms – Gums and
Skin
Vitamin C
 Toxicity
 Safe doses
 Recommendations
 Tobacco use
 Physical stressors
 Food sources
 Destruction of vitamin C
Vitamin C – Snapshot
The B Vitamins in Unison
 Function as part of coenzymes
 Combines with enzyme to activate it
 Coenzyme shape
 Roles in metabolism
 Help the body use the energy-yielding
nutrients for energy
 Cell multiplication
Coenzyme Action
Some Roles of the B Vitamins in
Metabolism: Examples
The B Vitamins in Unison
 Deficiencies
 Every cell is affected
 Symptoms
 Rarely are isolated deficiencies
Thiamin
 Energy metabolism of all
cells
 Nerve cell membranes
 Deficiency
 Beriberi
 Alcohol abuse
 DRI recommendation
 Food sources
Thiamin Snapshot
Riboflavin
 Role in energy metabolism of all cells
 Deficiencies
 Examples
 Destruction of vitamin
 UV light
 Irradiation
 Heat
Riboflavin Snapshot
Niacin
 Participates in
energy metabolism
 Deficiency
 Pellagra
 Toxicity
 Physician
administration
 “Niacin flush”
Niacin Snapshot
Folate
 Helps synthesize DNA
 Normal metabolism of several amino acids
 Deficiency
 Causes
 Outcomes of deficiency
 Anemia, diminished Immunity, abnormal
digestive function
 Cancer risk
 Interaction with medications
Folate
 Birth defects
 Neural tube defects (NTD)
 Toxicity
 UL
 Recommendations
 Food sources of folate
 Destruction of folate
Incidence of a Common NTD,
Spina Bifida, Over Time
Folate Snapshot
Vitamin B12
 Closely related to folate
 Helps maintain sheaths around nerve fibers
 Deficiency
 May be masked by folic acid intake
 Pernicious anemia
 Vitamin B12 absorption
 Intrinsic factor
 Food sources
Vitamin B12 Snapshot
Vitamin B6
 Roles
 Participates in over 100 reactions
 Additional roles
 Deficiency
 General symptoms
 Toxicity
 Intake recommendations
 Food sources
Vitamin B6 Snapshot
Biotin and Pantothenic Acid
 Important for energy metabolism
 Biotin
 Cofactor for enzymes
 Gene expression
 No UL
 Pantothenic acid
 Key coenzyme
Non-B Vitamins
 Choline
 Nonvitamins
 Carnitine
 Inositol
 Lipoic acid
Vitamin Supplements: Do the
Benefits Outweigh the Risks?
Controversy 7
Some Valid Reasons for Taking
Supplements
Arguments Against Taking
Supplements
 Food rarely causes nutrient imbalances or
toxicities
 Toxicity
 Supplement contamination
 Lift-threatening misinformation
 Unknown needs
 False sense of security
 Whole foods are best
Can Supplements Prevent Heart
Disease or Cancer?
 Oxidative stress
 Vitamin C
 Population studies
 Animal studies
 Cell studies
 Intervention studies
 Vitamin E
 Beta-carotene
Supplements Safety and Risks
 Safety
 Food and Drug Association (FDA)
 Risks
 Dangers for your body
Selecting a Supplement
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Choose type
Read labels
Target your needs
Choosing doses
Quality
Avoid marketing
traps