Chapter 7
The Vitamins
Nutrition: Concepts & Controversies, 12e
Sizer/Whitney
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 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
Vitamin D
 Body can synthesize all it needs
 Sunlight
 Transformation
 Liver and kidneys
 Estimated deficiency prevalence
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 – 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
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
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 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 Snapshot
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