Download Fundamentals of Nutrition

Chapter 7
Vitamins
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Objectives
• Of the 13 vitamins discussed:
– State one or more functions of each vitamin
– Identify at least two food sources of each vitamin
– Identify some symptoms of or diseases caused by vitamin
deficiencies
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Facts
•
•
•
•
Organic (carbon-containing) compounds
Essential in small amounts for body processes
Do not provide energy
Enable body to use energy provided by fats,
CHO, and proteins
• Megadoses can be toxic
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Thirteen Vitamin Types
• Four fat-soluble:
–
–
–
–
Vitamin A
Vitamin D
Vitamin E
Vitamin K
(continues)
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Thirteen Vitamin Types
• Nine water-soluble:
– Vitamin B complex, including the following:
• Thiamine (B1), riboflavin (B2), niacin, vitamin B6, folate, vitamin
B12 (cobalamin), pantothenic acid, and biotin
– Vitamin C
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Requirements
• Vitamin allowances given by weight in mg or
micrograms (mcg or g)
• DRIs have replaced RDAs
• Tolerable upper limits (UL)
– Maximum level of daily intake unlikely to cause adverse
effects
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Vitamin Deficiency
• People prone to vitamin deficiency:
–
–
–
–
–
Alcoholics
Poor and incapacitated elderly
Clients with serious diseases that affect appetite
Mentally retarded
Children receiving inadequate care
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Deficiency of Fat-Soluble Vitamins
• Chronic malabsorption diseases:
– Cystic fibrosis
– Celiac disease
– Crohn’s disease
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Stop and Share
• Match the following terms with their correct
definition:
1. Avitaminosis
A. Concentrated form of vitamins
2. Hypervitaminosis
B. Without vitamins
3. Vitamin supplement C. Condition caused by ingestion of
excess vitamins
(continues)
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Stop and Share
• Answers:
– 1B
– 2C
– 3A
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Preserving Vitamin Content in Food
• Buy fresh, unbruised vegetables and fruits
– Use them raw when possible
• Prepare fresh vegetables and fruits just before
serving
(continues)
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Preserving Vitamin Content in Food
• Heat canned vegetables quickly and in their
own liquid
• Follow package directions when cooking
frozen vegetables or fruit
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Avoiding Vitamin Loss
• Steam or use as little water as possible
• Cover pan and cook vegetables until bright in
color and crisp-tender
• Save any cooking liquid for soups, stews, and
gravy
(continues)
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Avoiding Vitamin Loss
• Store fruits and vegetables in cool, dark place
• Microwave produce in 1 to 2 tablespoons
(tbsp) of water
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Fat-Soluble Vitamins
•
•
•
•
•
Vitamin A, vitamin D, vitamin E, and vitamin K
Not lost easily in cooking
Lost when mineral oil ingested
Excess amounts stored in liver
Deficiencies slow to appear
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Vitamin A
• Preformed
– Retinol
• Active form of vitamin A
• Provitamin A carotenoids
– Beta carotene, lutein, lycopene, and zeaxanthin
– Inactive form of vitamin A found in plants
• Converted to retinol
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Functions of Vitamin A
• Maintains healthy eyes and skin
• Maintains normal bone growth and
reproduction
• Sustains healthy immune system
• Has antioxidants that protect cells from free
radicals
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Sources of Vitamin A
• Preformed vitamin A (retinol):
– Fat-containing animal foods
– Liver, butter, cream, whole milk, cheese, and egg yolk
• Beta carotene:
– Carrots, sweet potatoes, spinach, broccoli, pumpkin,
squash, mango, and cantaloupe
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Vitamin A Requirements
• Commonly listed as retinol equivalents (RE)
– 1 g retinol or 6 g beta carotene
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Stop and Share
• Consider the following questions:
– What are the signs and symptoms you would expect to
observe with too much vitamin A?
– What are the signs and symptoms you would expect to
observe with too little vitamin A?
(continues)
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Stop and Share
• Excess
–
–
–
–
–
–
–
–
• Deficit
Birth defects
Hair loss
Dry skin
Headaches
Nausea
Dry mucous membranes
Liver damage
Bone and joint pain
– Night blindness
– Dry, rough skin
– Increased susceptibility
to infections
– Blindness or
xerophthalmia
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Vitamin D
• Prohormone
– Converted to hormone in body
• D2
– Ergocalciferol
– Formed in plants
• D3
– Cholecalciferol
– Formed in humans from cholesterol in skin
• Values given in mcg or International Units
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Functions of Vitamin D
• Promotes calcium and phosphorus absorption
• Building and maintenance of normal bones and
teeth
• Prevention of tetany
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Sources of Vitamin D
• Sunlight
– Changes provitamin to vitamin D3
– People with little sun exposure must get sufficient intake
from diet
• Food sources:
– Milk, fish liver oils, egg yolk, butter, and fortified margarine
• Most milk in U.S. has 10 g vitamin D concentrate added per quart
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Stop and Share
• Consider the following questions:
– What are the signs and symptoms you would expect to
observe with too much vitamin D?
– What are the signs and symptoms you would expect to
observe with too little vitamin D?
(continues)
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Stop and Share
• Excess
• Deficit
– Deposits of calcium
and phosphorus in soft
tissues
– Kidney and heart
damage
– Bone fragility
– Poor bone and tooth formation
– Rickets
• Causes malformed bones and
pain in infants
– Osteomalacia
• Soft bones
– Osteoporosis
• Brittle, porous bones
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Vitamin E
• Tocopherols
– Alpha
• Most biologically active
– Beta, delta, and gamma
• Tocotrienols
• Given as -TE (alpha-tocopherol equivalents)
• 1 mg of -TE = 1 International Unit
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Functions of Vitamin E
• Serves as antioxidant
• Prevents hemolytic anemia among premature
infants
• Enhances immune system
• Retards spoilage of commercial foods
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Sources of Vitamin E
• Vegetable oils:
– Corn, soybean, safflower, cottonseed, and products made
from them
• E.g., margarine
• Wheat germ, nuts, and green leafy vegetables
• U.S. diet typically contains sufficient amount
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Stop and Share
• Consider the following questions:
– Your client asks you if it is possible to take too much
vitamin E. How would you advise the client?
– What signs and/or symptoms can result from too little
vitamin E?
(continues)
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Stop and Share
• Excess
• Deficit
– Relatively nontoxic, fatsoluble vitamin
– Stored in adipose tissue
– Avoid long-term
megadoses
– Serious neurological
defects can occur from
malabsorption
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Vitamin K
• Made up of several compounds essential to
blood clotting
• Vitamin K1
– Phylloquinone
• Vitamin K2
– Menaquinone
(continues)
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Vitamin K
• Synthetic vitamin K
– Menadione
• Destroyed by light and alkalies
• Must be ingested daily
• Measured in mcg
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Functions of Vitamin K
• Forms prothrombin for blood clotting
• Candidates likely to receive vitamin K:
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–
–
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Newborns immediately after birth
Clients with faulty fat absorption
People who have had extensive antibiotic therapy
People who need antidote for overdose of anticoagulant or
treatment of hemorrhage
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Sources of Vitamin K
• Green leafy vegetables
– E.g., broccoli, cabbage, spinach, kale
• Dairy products, cow’s milk, eggs, meats,
fruits, and cereals
• Bacteria in small intestine synthesizes some,
but must be supplemented by dietary sources
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Stop and Share
• Consider the following questions:
– What are the signs and symptoms you would expect to
observe with too much vitamin K?
– What are the signs and symptoms you would expect to
observe with too little vitamin K?
(continues)
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Stop and Share
• Excess
• Deficit
– Anemia
– Defective blood coagulation
• From synthetic form
• Increases clotting time
• Makes client prone to
hemorrhage
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Water-Soluble Vitamins
• Vitamin B complex and vitamin C
• Dissolve in water
• Easily destroyed by air, light, and cooking
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Vitamin B Complex: Thiamine (B1)
• Essential for the following:
– Nerve and muscle action
– Metabolism of carbohydrates and some amino acids
• Sources:
– Unrefined and enriched cereals, whole grains, lean pork,
liver, seeds, nuts, and legumes
(continues)
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Vitamin B Complex: Thiamine (B1)
• Deficiency rare
– Symptoms:
• Loss of appetite, fatigue, nervous irritability, and constipation
• Beriberi
– Disease caused by extreme deficiency
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Vitamin B Complex: Riboflavin (B2)
• Necessary for the following:
– Metabolism of carbohydrates, protein, and fats
– Tissue maintenance
• Especially skin around mouth
– Healthy eyes
• Sources:
– Milk, meats, poultry, fish, enriched breads, cereals,
broccoli, spinach, and asparagus
(continues)
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Vitamin B Complex: Riboflavin (B2)
• Deficiency symptoms:
– Cheilosis
• Sores on lips and cracks at corners of mouth
– Glossitis
• Inflammation of tongue
– Dermatitis
– Eye strain
• Itching, burning, and eye fatigue
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Vitamin B Complex: Niacin
• Generic name for nicotinic acid and
nicotinamide
• Coenzyme in energy metabolism
• Sources:
– Meats, poultry, fish, peanuts, and legumes
• Sources of tryptophan, precursor of niacin:
– Milk and eggs
(continues)
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Vitamin B Complex: Niacin
• Measured in niacin equivalents (NE)
• Excessive amounts can cause flushing
– Due to vascular dilation, gastrointestinal problems, itching,
and liver damage
(continues)
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Vitamin B Complex: Niacin
• May be used as cholesterol-lowering agent
under close supervision of physician
– Due to adverse side effects:
• Liver damage
• Peptic ulcers
(continues)
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Vitamin B Complex: Niacin
• Deficiency symptoms:
– Weakness, anorexia, indigestion, anxiety, and irritability
• Pellagra
– Disease caused by extreme deficiency
– Symptoms:
• Sores on skin, diarrhea, anxiety, confusion, irritability, poor
memory, dizziness, and untimely death
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Vitamin B Complex: B6
• Pyridoxine, pyridoxal, and pyridoxamine
• Essential for the following:
– Protein metabolism and absorption
– Aiding release of glucose from glycogen
• Catalyst in conversion of tryptophan to niacin
• Helps synthesize neurotransmitters
– E.g., serotonin, dopamine
(continues)
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Vitamin B Complex: B6
• Sources:
– Poultry, fish, liver, kidney, potatoes, bananas, spinach, and
unrefined whole grains (oats and wheat)
• Measured in mg
• Deficiency symptoms:
– Irritability, depression, and dermatitis
(continues)
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Vitamin B Complex: B6
• Deficiency in infants can cause various
neurological symptoms and abdominal
problems
• Toxicity rare
– May cause temporary neurological problems
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Vitamin B Complex: B12
• Cobalamin
– Contains mineral cobalt
• Involved in the following:
– Folate metabolism
– Maintenance of myelin sheath
– Preservation of healthy RBCs
(continues)
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Vitamin B Complex: B12
• To be absorbed, must bind with intrinsic factor
in stomach
• Sources:
– Animal foods
• Especially organ meats, lean meats, seafood, eggs, and dairy
products
• Increased need during pregnancy and lactation
(continues)
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Vitamin B Complex: B12
• Deficiency rare
– May be due to congenital problems of absorption or years
of vegetarian diet with no animal foods
– Symptoms:
• Megaloblastic anemia, pernicious anemia (if intrinsic factor
absent), anorexia, glossitis, sore mouth, tongue, pallor, depression,
dizziness, and weight loss
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Vitamin B Complex: Folate
• Folate, folacin, and folic acid
– Chemically similar compounds
– Names used interchangeably
• Necessary for the following:
– Deoxyribonucleic acid (DNA) synthesis
– Protein metabolism
– Formation of hemoglobin
(continues)
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Vitamin B Complex: Folate
• Sources:
– Cereals fortified with folate, green leafy vegetables,
legumes, sunflower seeds, and fruits (e.g., oranges,
strawberries)
• Measured in mcg
• Average adult requires 400 g per day
(continues)
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Vitamin B Complex: Folate
• One month before conception through first six
weeks of pregnancy requires 600 g per day
• Excess can mask vitamin B12 deficiency and
inactivate phenytoin
– Anticonvulsant drug used by epileptics
• Important role in some cancer prevention
(continues)
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Vitamin B Complex: Folate
• Deficiency linked to neural tube defects in
fetus:
– Spina bifida
• Spinal cord or spinal fluid bulge through back
– Anencephaly
• Absence of brain
(continues)
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Vitamin B Complex: Folate
• Other deficiency symptoms:
– Inflammation of mouth and tongue, poor growth,
depression and mental confusion, problems with nerve
functions, and megaloblastic anemia
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Vitamin B Complex: Biotin
• Coenzyme in synthesis of fatty acids and
amino acids
• Sources:
– Egg yolks, milk, poultry, fish, broccoli, spinach, and
cauliflower
• Also synthesized in intestine by microorganisms
(continues)
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Vitamin B Complex: Biotin
• Toxicity from excess unknown
• Deficiency symptoms:
– Nausea, anorexia, depression, pallor, dermatitis, and
increase in serum cholesterol
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Vitamin B Complex: Pantothenic
Acid
• Involved in metabolism of carbohydrates, fats,
and proteins
• Essential for the following:
– Synthesis of neurotransmitter acetylcholine
– Synthesis of steroid hormones
• Sources:
– Meats, poultry, fish, eggs, whole-grain cereals, and legumes
(continues)
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Vitamin B Complex: Pantothenic
Acid
• Considered synthesized by body
• Toxicity from excess unknown
• Natural deficiencies unknown
– Deficiencies produced experimentally
• Symptoms include weakness, fatigue, burning sensation in feet
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Vitamin C: Ascorbic Acid
• Antioxidant properties
• Protects food from oxidation
• Role in formation of collagen and absorption
of nonheme iron
• Prevents scurvy
(continues)
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Vitamin C: Ascorbic Acid
• May be involved with formation or functioning
of norepinephrine, some amino acids, folate,
leukocytes, immune system, and allergic
reactions
(continues)
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Vitamin C: Ascorbic Acid
• Sources:
– Citrus fruits, melons, strawberries, tomatoes, potatoes, red
and green peppers, cabbage, and broccoli
• Stress and cigarette smoking increase need
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Stop and Share
• Consider the following questions:
– What disease results from a deficiency in vitamin C?
– What are the associated signs and/or symptoms?
– What results from an excess of vitamin C?
(continues)
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Stop and Share
• Scurvy
– Disease characterized by gingivitis, easy bruising, pinpoint
hemorrhages of skin, poor wound healing, sore joints and
muscles, and weight loss
– Extreme cases result in death
• Found in sailors who have lived without fresh
fruits and vegetables
(continues)
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Stop and Share
• Excess
–
–
–
–
• Deficit
Diarrhea
Nausea
Cramps
Excessive absorption of
food iron
– Bleeding gums
– Loose teeth
– Tendency to bruise
easily
– Poor wound healing
– Scurvy
(continues)
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Stop and Share
• Excess
– Rebound scurvy (when
megadoses abruptly
stopped)
– Possibly oxalate kidney
stones
• Generally considered
nontoxic
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Vitamin Supplementation
• Balanced diet provides nutritional needs of
healthy people
• No amount of vitamins will build muscles
• Vitamins do not provide energy
– Help release energy provided by nutrients
• Supplements should not exceed 100 percent of
DRI for each vitamin
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Conclusion
• Vitamins:
– Organic compounds that regulate body functions and
promote growth
– Each has specific function
• Well-balanced diet provides sufficient
vitamins to fulfill body requirements
(continues)
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Conclusion
• Fat-soluble vitamins:
– Vitamin A, vitamin D, vitamin E, and vitamin K
• Water-soluble vitamins:
– Vitamin B complex and vitamin C
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