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week3ch.pptxChapter 7 Vitamins:
Vital Keys to Health
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Understanding Vitamins
Vitamins
Needed in small amounts
Not an energy source
Individual units rather than long chains
Essential for normal functioning, growth, and maintenance of the body
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Understanding Vitamins
Fat-soluble vs. water-soluble
Fat-soluble: Vitamins A, D, E, K
Absorbed with fat into lymphatic system
Stored in larger quantities
Less vulnerable to cooking losses
Water-soluble: B Vitamins and Vitamin C
Absorbed into bloodstream
Stored in small amounts
Vulnerable to cooking losses
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Understanding Vitamins
Food preparation affects vitamins in foods
Vitamins found in all food groups
Factors that determine amounts
Source (animal vs. plant)
Sunlight
Moisture
Growing conditions
Plant’s maturity at harvest
Packaging and storage
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Food preparation affects vitamins in foods
Enrichment and fortification
Enrichment—replacing lost nutrients in processed foods
Fortification—adding extra nutrients to foods that wouldn’t have them naturally
Some is required by law
Understanding Vitamins
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Food preparation affects vitamins in foods
Provitamins
Inactive
Body must change them to active form
Example: beta-carotene
Understanding Vitamins
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Vitamin A: The Retinoids
Forms of Vitamin A
Active forms (retinoids)
Retinol
Retinal
Retinoic acid
Precursors (carotenoids)
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Vitamin A: The Retinoids
Functions
Vision
Maintaining healthy cells
Fighting infections and bolstering immune function
Promoting growth and development
Cell development and health
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Vitamin A
Functions of vitamin A
Vision: night and day
Changes incoming light to visual images
Keeps eye’s surface healthy
Allows night and color vision
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Vitamin A
Functions of vitamin A
Cell production and differentiation
Regulates production of enzymes, blood carrier proteins, and structural proteins (like those in the skin)
Skin
Needed to replace epithelial cells
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Vitamin A
Functions of vitamin A
Immune function
Produce immune cells
Reproduction
Keep reproductive tracts healthy
Bones
Helps produce bone cells
Required for bone remodeling
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Vitamin A
Dietary Recommendations
Retinol activity equivalent (RAE)
Sources of Vitamin A
Animal food sources (retinoids)
Plant food (provitamin A carotenoids)
Fortified foods
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Vitamin A
Vitamin A Deficiency
Rare in North America and Western Europe
Leading cause of child blindness worldwide
Affects eyes, body cell development, and immune function
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Vitamin A
Vitamin A Deficiency
The Eyes
Xerophthalmia
The Skin and Other Epithelial Cells
Keratin
Immune function
Vulnerable to infection
Other Effects
Growth retardation, bone deformities, defective teeth, and kidney stones
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Vitamin A
Vitamin A Toxicity
Symptoms
Fatigue, vomiting, abdominal pain, bone and joint pain, loss of appetite, skin disorders, headache, blurred or double vision, and liver damage
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Vitamin A
Vitamin A Toxicity
Teratogen
Causes birth defects
Discoloration of skin
Acne treatment
Retin-A and Accutane
Use with caution
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The Carotenoids
Plant pigments
Major Carotenoids
Alpha-carotene
Beta-carotene (most common)
Lutein
Zeaxanthin
Cryptoxanthin
Lycopene
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The Carotenoids
Functions of carotenoids
Not technically essential
Can function as potent antioxidants
Protect vision
Lowers risk of certain cancers
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Food Sources, Absorption, and Storage of Carotenoids
Good sources
Orange and yellow fruit and vegetables, dark green vegetables
Body absorbs 20–40% of carotenoids eaten
Dietary fat increases absorption
Photo © PhotoDisc
The Carotenoids
Vitamin D
Forms and formations
Activated in liver and kidney
25-hydroxyvitamin D [25(OH)D]
Functions
Essential for bone health
Protects against certain cancers and other chronic diseases
Helps regulate insulin formation and secretion
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Vitamin D
Sources
Exposure to sunlight
Fortified foods
Milk
Breakfast cereals
Supplements
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Vitamin D
Deficiency
Rickets in children
Osteomalacia and osteoporosis in
adults
Toxicity
Hypercalcemia
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Vitamin E
Forms
Family of eight similar compounds
Only alpha-tocopherol considered for human vitamin E requirement
Stored mainly in body fat
Functions
Antioxidant
Protects cell membranes from free radicals
May lower risk of some chronic diseases
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Vitamin E
Dietary Recommendations
Related to intake of polyunsaturated fatty acids
RDA
15 mg/day alpha tocopherol for adults
19 mg/day for breastfeeding
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Vitamin E
Food Sources
Nuts, seeds, vegetable oil, whole grain, wheat germ oil, fruit, vegetables, and animal products
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Vitamin E
Deficiency
Occurs with fat malabsorption or rare genetic disorders
Toxicity
Nontoxic and adverse effects have not been found
Can interfere with blood clotting
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Vitamin K
Functions
Blood clotting
Bone health
Dietary Recommendations
Men 120 mg/day
Women 90 mg/day
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Vitamin K
Food sources
Green vegetables, plant oils, intestinal bacteria
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Vitamin K
Deficiency
Rare in healthy people
Newborn babies at risk
Toxicity
Rare
Can interfere with anticoagulant medications
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The Water-Soluble Vitamins
Eight B Vitamins
Act primarily as coenzymes in energy metabolism
Vitamin C
Antioxidant
Can stabilize Vitamin E
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Thiamin
Functions
Coenzyme in energy metabolism
Part of the coenzyme thiamin pyrophosphate (TPP)
Helps break down glucose, make RNA and DNA; helps power protein synthesis
Helps synthesize and regulate neurotransmitters
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Thiamin
Dietary recommendations
Men 1.2 mg/d
Women 1.1 mg/d
Pregnancy 1.4 mg/d
Breastfeeding 1.5 mg/d
Food sources
Pork, legumes, nuts and seeds, fish and seafood, enriched grain products
Cooking reduces content
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Thiamin
Deficiency
Beriberi: Overall profound muscle weakness and nerve destruction
Milder symptoms: Headache, irritability, depression, and loss of appetite
Toxicity
No reports of thiamin toxicity
Riboflavin
Functions
Coenzyme in energy metabolism
Supports antioxidants
Food sources
Milk and dairy products
Enriched grains, eggs
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Riboflavin
Deficiency
Ariboflavinosis
Occurs most often in chronic alcoholism
Toxicity
No reported cases
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Niacin
Functions
Coenzyme in energy metabolism
Supports fatty acid synthesis
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Niacin
Food sources
Can be made from amino acid tryptophan
Whole and enriched grains
Meat, poultry, fish, nuts, and peanuts
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Niacin
Deficiency
Pellagra
“Four Ds”: Dermatitis, diarrhea, dementia, and death
Toxicity and Medicinal uses
High doses used to treat high blood cholesterol
Side effects: skin flushing, liver damage
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Vitamin B6
Functions
Coenzyme in protein and amino acid metabolism
Supports immune system
Helps to lower blood levels of homocysteine
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Vitamin B6
Food sources
Meat, fish, poultry, potatoes, fortified meat substitutes, bananas, sunflower seeds
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Vitamin B6
Deficiency
Microcytic hypochromic anemia
Toxicity and Medicinal Uses
Can cause subtle neurological damage, upset stomach, headache, sleepiness, and a tingling, prickling, or burning sensation
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Folate
Functions
Coenzyme in DNA synthesis and cell division
Needed for normal red blood cell synthesis
Reduces neural tube defects
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Folate
Food sources
Fortified cereals, enriched grains
Green leafy vegetables, orange juice, sunflower seeds, and legumes
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Folate
Deficiency
Anemia and diarrhea
Megaloblastic anemia
Birth defects
Spina bifida
Heart disease
Toxicity
Can mask vitamin B12 deficiency
Hypersensitive people may suffer hives or respiratory distress
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Vitamin B12
Functions
Needed for normal folate function
DNA and red blood cell synthesis
Metabolize homocysteine
Maintains myelin sheath around nerves
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Vitamin B12
Food sources
Only animal foods: meats, liver, milk, eggs, some fortified foods
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Vitamin B12
Absorption
Requires adequate stomach acid and intrinsic factor
Deficiency
Can lead to pernicious anemia, resulting in nerve damage
Toxicity
No UL set
Pantothenic Acid
Functions
Component of coenzyme A
Food sources
Widespread in foods
Reduced by freezing, canning, and refining
Deficiency and toxicity are rare
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Biotin
Functions
Coenzyme
Amino acid metabolism
Fatty acid synthesis
Release of energy from fatty acids
DNA synthesis
Food sources
Cauliflower, liver, peanuts, cheese
Protein avidin (raw egg whites) binds biotin and prevents absorption
Deficiency and toxicity are rare
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Choline: A Vitamin-Like Substance
Function
Helps metabolize homocysteine
Food sources
Milk, liver, egg yolk, and peanuts
Overall abundant in food
Deficiency
Unlikely in healthy people
Toxicity
Diarrhea, falling blood pressure, and fishy body odor
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Vitamin C
Functions
Antioxidant
Needed for collagen synthesis
Other roles
Makes other essential compounds
Enhances the absorption of iron from plant foods
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Vitamin C
Food sources
Fruits: citrus, strawberries, kiwi, fortified juice
Vegetables: broccoli, tomatoes, potatoes, cabbage, leafy green, peppers
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Vitamin C
Deficiency
Scurvy
Toxicity
May cause GI distress in high doses
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Conditional Nutrients
Body makes most substances needed for life
May need to get from diet due to illness or inherited metabolic errors—thus conditional
Examples
Inositol
Carnitine
Taurine
Lipoic acid
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Bogus Vitamins
Unnecessary substances found in some supplements
May be marketed as “vitamins” and “health boosters”
Examples
Hesperidin
Pangamic acid
Rutin
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