Chapter 7 The Vitamins

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Chapter 7The Vitamins

• Nutrition Concepts Controversies, 12e
  Sizer/Whitney

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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.

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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.

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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.

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Definition and Classification of Vitamins

• Vitamin
• Essential, noncaloric, organic
• Role of vitamins
• Vitamin precursors
• Classes
• Absorption
• Roles

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Vitamin Names
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Characteristics of the Fat-Soluble and
Water-Soluble Vitamins
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The Fat-Soluble Vitamins

• A, D, E, and K
• Food sources
• Storage
• Toxicity
• Deficiency
• Roles within the body

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Vitamin A

• Precursor
• Beta-carotene
• Active forms in the body
• Retinol
• Retinal
• Retinoic acid
• Food sources

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Vitamin A Roles and Deficiency

• Gene regulation
• Retinoic acid
• Eyesight
• Process of light perception
• Maintenance of healthy cornea
• Rhodopsin molecule

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An Eye
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Vitamin A Roles and Deficiency

• Night blindness
• Deficiency
• Xerophthalmia and blindness
• Keratinization
• Deficiency
• Cell differentiation
• Immune function
• Growth

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Vitamin A Deficiency and Toxicity

• Deficiency
• Worldwide problem
• Blindness
• HIV
• Toxicity
• Symptoms
• food sources
• Liver

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Vitamin A Deficiency and Toxicity

• Toxicity
• Supplements
• Higher risk groups
• Recommendations
• DRI recommendation based on body weight
• Food sources
• Animal origin
• Liver
• Plant origin

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Vitamin A Deficiency and Toxicity
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Vitamin A Snapshot
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Beta-Carotene

• Plant-based foods
• Colorful groups
• Macular degeneration
• Dietary antioxidant
• Measuring beta-carotene
• Retinol activity equivalents (RAE)
• Toxicity
• Food sources

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Excess Beta-Carotene Symptom Discoloration of
the Skin
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Vitamin D

• Body can synthesize all it needs
• Sunlight
• Transformation
• Liver and kidneys
• Estimated deficiency prevalence

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Vitamin D Roles

• Bone integrity
• Hormone
• Dangers with deficiency

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Vitamin D Too Little, Too Much

• Deficiency
• Rickets
• Recommendations for prevention
• Osteomalacia
• Recommendations
• Toxicity
• Signs of toxicity

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Rickets
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Vitamin D

• Ultraviolet B light rays
• Cholesterol
• Sunbathing risks
• Sunscreen
• Exposure times
• Intake recommendations
• Food sources

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Factors Affecting Vitamin D Synthesis
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Vitamin D - Snapshot
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Vitamin E

• Roles of vitamin E
• Antioxidant
• Deficiency
• Symptoms
• Toxicity
• Dietary intake vs. supplemental intake
• Recommendations
• Food source

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Free-Radical Damage and Antioxidant Protection
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Vitamin E Snapshot
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Vitamin K

• Roles
• Blood clotting
• Bone proteins
• Deficiency
• Toxicity
• Jaundice
• Requirements
• Sources

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Vitamin K Snapshot
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The Water-Soluble Vitamins

• Dissolve in water
• Absorption
• Transport
• Excretion
• Sources
• Food
• Supplements

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Vitamin C

• Roles
• Connective tissues
• Collagen
• Antioxidant
• Protects iron
• Prooxidant
• Deficiency symptoms
• Scurvy

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Scurvy Symptoms Gums and Skin
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Vitamin C

• Toxicity
• Safe doses
• Recommendations
• Tobacco use
• Physical stressors
• Food sources
• Destruction of vitamin C

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Vitamin C Snapshot
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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

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Coenzyme Action
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Some Roles of the B Vitamins in Metabolism
Examples
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The B Vitamins in Unison

• Deficiencies
• Every cell is affected
• Symptoms
• Rarely are isolated deficiencies

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Thiamin

• Energy metabolism of all cells
• Nerve cell membranes
• Deficiency
• Beriberi
• Alcohol abuse
• DRI recommendation
• Food sources

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Thiamin Snapshot
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Riboflavin

• Role in energy metabolism of all cells
• Deficiencies
• Examples
• Destruction of vitamin
• UV light
• Irradiation
• Heat

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Riboflavin Snapshot
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Niacin

• Participates in energy metabolism
• Deficiency
• Pellagra
• Toxicity
• Physician administration
• Niacin flush

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Niacin Snapshot
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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

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Folate

• Birth defects
• Neural tube defects (NTD)
• Toxicity
• UL
• Recommendations
• Food sources of folate
• Destruction of folate

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Incidence of a Common NTD, Spina Bifida, Over Time
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Folate Snapshot
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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

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Vitamin B12 Snapshot
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Vitamin B6

• Roles
• Participates in over 100 reactions
• Additional roles
• Deficiency
• General symptoms
• Toxicity
• Intake recommendations
• Food sources

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Vitamin B6 Snapshot
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Biotin and Pantothenic Acid

• Important for energy metabolism
• Biotin
• Cofactor for enzymes
• Gene expression
• No UL
• Pantothenic acid
• Key coenzyme

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Non-B Vitamins

• Choline
• Nonvitamins
• Carnitine
• Inositol
• Lipoic acid

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Vitamin Supplements Do the Benefits Outweigh the
Risks?

• Controversy 7

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Some Valid Reasons for Taking Supplements
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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

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Can Supplements Prevent Heart Disease or Cancer?

• Oxidative stress
• Vitamin C
• Population studies
• Animal studies
• Cell studies
• Intervention studies
• Vitamin E
• Beta-carotene

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Supplements Safety and Risks

• Safety
• Food and Drug Association (FDA)
• Risks
• Dangers for your body

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Selecting a Supplement

• Choose type
• Read labels
• Target your needs
• Choosing doses
• Quality
• Avoid marketing traps