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The Vitamins – An Overview
The Water-Soluble
Vitamins: B Vitamins
and Vitamin C
Chapter 10
 Support nutritional health
 Vitamins differ from macronutrients
 Structure
 Individual units
 Function
 No energy yielded
 Food contents
 Similarities to macronutrient
Whitney & Rolfes – Understanding Nutrition, 12th
Edition
The Vitamins – An Overview
 Bioavailability
 Quantity provided by food
 Amount absorbed and used by body
 Factors influencing bioavailability
 Efficiency of digestion
 Nutrition status
 Method of food preparation
 Source of nutrient
 Other foods consumed at same time
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The Vitamins – An Overview
 Precursors
 Provitamins
 Converted to active form in body
 Organic nature
 Can be destroyed during storage and in
cooking
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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The Vitamins – An Overview
 Solubility
 Affects absorption, transport, and excretion
 Water-soluble
 Move directly into blood
 Most travel freely
The Vitamins – An Overview
 Toxicity
 More is not necessarily better
 Excessive intakes
 Levels higher than UL
 Fat-soluble
 Enter lymph and then blood
 Require transport proteins
 Consumption frequency of vitamins
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The Vitamins – An Overview
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – As
Individuals
 Vitamins do not provide the body with fuel
for energy
 Coenzymes
 Assist enzymes with release of energy
 Without coenzyme, an enzyme cannot
function
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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The B Vitamins – As
Individuals
The B Vitamins – Thiamin
 Part of coenzyme thiamin pyrophosphate
(TPP)
 Energy metabolism
 Conversion of pyruvate to acetyl CoA
 TCA cycle
 Nerve activity and muscle activity
 Recommendations
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Thiamin
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Thiamin
 Deficiency
 Malnourished and alcoholics
 Beriberi
 Dry – nervous system
 Wet – cardiovascular system
 Toxicity
 No adverse effects
 No UL
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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The B Vitamins – Thiamin
The B Vitamins – Thiamin
 Food sources
 Prolonged cooking destroys thiamin
 Leaches into water when boiling or
blanching foods
 Cooking methods that conserve thiamin
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Riboflavin
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Riboflavin
 Serves as coenzyme in energy metabolism
 Flavin mononucleotide (FMN)
 Flavin adenine dinucleotide (FAD)
 Recommendations
 Deficiency
 Inflammation of membranes
 Toxicity
 No UL
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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The B Vitamins – Riboflavin
The B Vitamins – Riboflavin
 Food sources
 Milk and milk products
 Other sources
 Destruction of riboflavin
 Ultraviolet light
 Irradiation
 Not destroyed by cooking
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Niacin
 Two chemical structures
 Nicotinic acid
 Nicotinamide
 Major form of niacin in blood
 Two coenzyme forms – metabolic reactions
 Nicotinamide adenine dinucleotide (NAD)
 Carries hydrogens and their electrons
 NADP (the phosphate form)
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Niacin
 Recommendations
 Body manufacturers from tryptophan
 Only occurs after protein synthesis needs
have been met
 RDA is stated in niacin equivalents
 Deficiency
 Pellagra
 Symptoms
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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The B Vitamins – Niacin
The B Vitamins – Niacin
 Toxicity
 Naturally occurring
 No harm
 Supplements or drugs
 “Niacin flush”
 Potential health benefits of large doses of
nicotinic acid
 Food sources
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Niacin
 Less vulnerable to food preparation losses
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Biotin
 Coenzyme that carries activated carbon
dioxide
 Critical in TCA cycle
 Delivers carbon to pyruvate to form
oxaloacetate
 Participates in gluconeogenesis and fatty
acid synthesis
 Participates in breakdown of fatty acids and
amino acids
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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The B Vitamins – Pantothenic
Acid
The B Vitamins – Niacin
 Recommendations
 Adequate intake (AI)
 Deficiencies
 Rare
 Symptoms
 Toxicity
 Part of chemical structure of coenzyme A
 Roles in body
 Recommendations
 AI
 Deficiency
 Rare
 No UL
 Food sources
 Toxicity
 Food sources
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – B6
 Three forms
 Pyridoxal, pyridoxine, and pyridoxamine
 Conversion to coenzyme PLP
 Amino acid metabolism
 Urea metabolism
 Conversion of tryptophan to niacin or
serotonin
 Synthesis of heme, nucleic acids, & lecithin
 Stored exclusively in muscle tissue
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – B6
 Recommendations
 Large doses
 Deficiency
 Symptoms
 Alcohol & isoniazid
 Toxicity
 Irreversible nerve degeneration
 Food sources
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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The B Vitamins – B6
The B Vitamins – Folate
 Known as folacin or folic acid
 Primary coenzyme form – THF
(tetrahydrofolate)
 Transfers single-carbon compounds during
metabolism
 Convert vitamin B12 to coenzyme form
 Synthesize DNA
 Regenerate methionine from homocysteine
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Folate
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Folate
 Folate disposal
 Secretion by liver into bile
 Enterohepatic circulation
 Vulnerable to GI tract injuries
 Recommendations
 Bioavailability of folate
 Synthetics vs. food sources
 Increased need
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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The B Vitamins – Folate
 Neural tube defects
 Supplement use
 1 month before conception
 Through first trimester
 Fortified grain products
 Congenital birth defects
 Safety concerns with fortification
 Mask a vitamin B12 deficiency
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Folate
 Heart disease
 Breakdown homocysteine
 Blood clots and atherosclerotic lesions
 Risk for heart attacks, stroke, or death from
cardiovascular causes
 Cancer
 Type of cancer
 Timing of supplementation
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Folate
 Deficiency
 Impairs cell division and protein synthesis
 Red blood cells and GI tract cells falter
 Anemia
 GI tract deterioration
 Primary deficiencies
 Secondary deficiencies
The B Vitamins – Folate
 Toxicity
 Naturally occurring from food sources
 Fortified foods or supplements
 UL has been established
 Food sources
 Heat and oxidation destroy folate
 Drugs
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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The B Vitamins – Folate
The B Vitamins – Vitamin B12
 Vitamin B12 and folate depend on each
other for activation
 Regeneration of methionine, synthesis of
DNA, and synthesis of RNA
 Individual roles of vitamin B12
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Vitamin B12
 Digestion and absorption
 Stomach
 Small intestine
 Intrinsic factor
 Transported in blood by specific binding
proteins
 Enterohepatic pathway
 Deficiency is rare
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – Vitamin B12
 Recommendations
 Deficiency
 Inadequate absorption
 Lack of hydrochloric acid or intrinsic factor
 Pernicious anemia
 Vegan diets
 Anemia of folate deficiency
 Symptoms of vitamin B12 deficiency
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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The B Vitamins – Vitamin B12
The B Vitamins – Vitamin B12
 Toxicity
 No adverse effects
 No UL
 Food sources
 Found almost exclusively from animal
products
 Bioavailability
 Fish and milk
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Vitamin-Like Compounds
 Choline
 Manufactured from methionine in body
 Conditionally essential nutrient
 Adequate intake (AI)
 Common sources
 Deficiencies are rare
 Roles in the body
 Destruction
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Vitamin-Like Compounds
 Inositol
 Part of cell membrane structures
 Carnitine
 Transports long-chain fatty acids for
oxidation
 Both can be made by body
 No recommendations established
 Both are widespread in foods
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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The B Vitamins – In Concert
 Each B vitamin coenzyme is involved in
energy metabolism
 Directly
 Indirectly
 Deficiencies
 Single B-vitamin deficiencies seldom show
up in isolation
 Beriberi and pellagra
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – In Concert
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The B Vitamins – In Concert
 Toxicities
 Excess eliminated through urine excretion
 Homeostasis disruption
 Toxicities develop
 Food sources
 First choice should be foods rather than
supplements
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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Vitamin C – Roles
Vitamin C – Roles
 Antioxidant
 Defends against free radicals
 Loses electrons easily
 Vitamin C recycling
 Protects tissues from oxidative stress
 Disease prevention
 Enhances iron absorption
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Vitamin C – Roles
 Cofactor in collagen formation
 Matrix for bone and tooth formation
 Conversion of proline to hydroxyproline
 Cofactor in other reactions
 Hydroxylation of carnitine
 Conversion of tryptophan to serotonin
 Conversion of tyrosine to norepinephrine
 Making hormones
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Vitamin C – Roles
 In stress
 Adrenal glands release vitamin C and
hormones into blood
 Types of stress that increase vitamin C
 Prevention and treatment of common cold
 Conflicting and controversial research
 Deactivates histamine
 Disease prevention
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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Vitamin C –
Recommendations
 Prevent overt
symptoms of scurvy
 Absorption maximum
 200 mg
 Higher vitamin C
levels for smokers
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Vitamin C – Deficiency
Vitamin C – Deficiency
 Notable signs of deficiency
 Gums bleed easily around teeth
 Capillaries under skin break spontaneously




Scurvy
Other physical signs
Psychological signs
Sudden death
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Vitamin C – Toxicity
 Supplementation side effects
 Diarrhea
 GI distress
 UL
 Interference with medical regimens
 Medical conditions in which high doses of
vitamin C should not be consumed
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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Vitamin C – Food Sources
Vitamin C – Food Sources
 Fruits and vegetables
 Potatoes
 Vulnerable to heat and oxygen
 Used as antioxidant by food manufacturers
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Vitamin and Mineral
Supplements
 Taken as dietary insurance
Highlight 10
Vitamin and Mineral Supplements
 Costly but harmless practice
 Costly and harmful to health practice
 Mostly self-prescribed
 Physician recommendation
 Improving food choices is preferred course
of action
 Registered Dietitian
Whitney & Rolfes – Understanding Nutrition, 12th
Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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Arguments for Supplements
 Correct overt deficiencies
 Therapeutic doses prescribed by physician
 Acting as drug
 Support increased nutrient needs
 Certain stages of life
 Improve nutrition status
 Improve body defenses
 Reduce disease risks
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Arguments Against
Supplements
 Toxicity
 Supplement users are more likely to have
excessive intakes
 Issues with children
 Life-threatening misinformation
 No guarantee of supplement effectiveness
 Unknown needs
 “Ideal” supplements
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Who Needs Supplements?
 Specific nutrient
deficiencies
 Low energy intakes
 Vegans and older
adults with atrophic
gastritis
 Lactose intolerance
 Certain medications
 Certain stages of life
cycle
 Inadequate milk
intake, sun
exposure, or dark
skin
 Medical conditions
that interfere with
nutrients in body
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Arguments Against
Supplements
 False sense of security
 Other invalid reasons
 Today’s health problems
 Overnutrition
 Poor lifestyle choices
 Bioavailability and antagonistic actions
 Nutrients may interfere with one another’s
action
 Make dietary modifications first
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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Selection of Supplements
 Follow directions carefully
 Single, balanced vitamin-mineral
supplement
 U.S. Pharmacopeia (USP) logo
 Logo assurances
 Two basic questions
 Form
 Contents
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Misleading Claims
 Organic or natural vitamins
 High potency claims
 Marketing strategy
 Fake vitamins
 “Green” pills
 Stress relief
 Internet advertising
 Cost
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Regulation of Supplements
 Food and Drug Administration (FDA)
 Dietary Supplement Health and Education
Act of 1994
 Enable consumers to make informed
choices
 Same general labeling requirements as
foods
 Net effect: deregulation of supplement
industry
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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