copyright © 2011 delmar, cengage learning. all rights reserved. chapter 7 vitamins
TRANSCRIPT
Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED.
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
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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
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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
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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
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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?
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Stop and Share
• Excess– Birth defects
– Hair loss
– Dry skin
– Headaches
– Nausea
– Dry mucous membranes
– Liver damage
– Bone and joint pain
• Deficit– 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– Deposits of calcium
and phosphorus in soft tissues
– Kidney and heart damage
– Bone fragility
• Deficit– 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?
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Stop and Share
• Excess– Relatively nontoxic, fat-
soluble vitamin
– Stored in adipose tissue
– Avoid long-term megadoses
• Deficit– 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
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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:– 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
Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED.
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– Anemia
• From synthetic form
• Deficit– Defective blood coagulation
• 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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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 micro-organisms
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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
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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
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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
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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
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Stop and Share
• Excess– Diarrhea
– Nausea
– Cramps
– Excessive absorption of food iron
• Deficit– 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
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