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Chapter 9: The Fat-Soluble
Vitamins
Vitamins Definitions
Organic compound found in foods, noncaloric
Required in small amounts Required in the diet (essential) Proven to be required for health, growth,
and reproduction ; deficiency syndrome identified
There are 4 fat soluble vitamins & 9 water soluble vitamins for a total of 13. Your text also lists choline with the water
soluble vitamins although it is not considered a vitamin since there is no known deficiency disease
FAT Soluble VitaminsADEK
Stored in tissues in larger quantities Soluble in lipids Not readily excreted;
High long term intakes can cause toxicity Less vulnerable to cooking losses Absorbed along with fat Transported like fat in chylomicrons,
VLDL, LDL Deficiencies due to fat mal-absorption or
very low fat diets or liver and pancreas disorders
Vitamin Absorption
Pro-VitaminsPrecursors of vitamins Are converted into the active
vitamin form E. g. beta-carotene converted
into vitamin A
Sources of Vitamin A
Chemical names: 3 forms: retinol, retinal, retinoic acid
Active forms: Preformed Retinoids (retinal, retinol, retinoic acid) In animal products: beef liver, fish, fish oils, eggs,
Pro-forms Carotenoids (beta-carotene, alpha carotene,lutien,
lycopene, zeaxanthin) Must be converted to retinoid form Found in plant products: carrots, spinach, sweet
potatoes, broccoli, romaine lettuce, mangoes, peaches
Functions of Vitamin A
Major use is in cell growth and differentiation Attaches nuclear retinoid acid
receptor (RAR) & retinoic X receptor (RXR)
Important for embryo development, gene expression
Associated with improved immune system
Functions of Vitamin A
Promotes proper fetal growth at proper times Acts as a morphogen
substances believed to be present in the growing embryo, controlling its growth pattern.
variations in the concentration of morphogens in different parts of the embryo cause them to grow at different rates.
Synthesis of bone protein and enlargement of bone
Production of mucus Promotes synthesis of keratin proteins
Skin, hair, nails
Functions of Vitamin A
Vision: Retina Cones vision in bright
lights Rods vision in dim
light Retinal combines with
opsin to form Rhodopsin = light capturing pigment
Carotenoids act as antioxidants
Lower risk of breast cancer with vitamin A supplements
Deficiency of Vitamin A
Night blindness Decreased mucus production Leading to bacterial invasion in the eye and
Xerophthalmia- dryness of cornea & eye membranes: read pg 298 Conjunctival xerosis Bitot’s spots Irreversible blindness amy result
Follicular hyperkeratosis the excessive development or retention of keratin
by the epidermis. Bumpy, rough, and dry skin, hair follicles become
plugged
RDA for Vitamin A for Adults
Units = Retinol Activity Equivalents 1 RAE = 1 ug (1/1 000 000 g) 900 REA for men (3000 REA max) 700 REA for women (Max: 3000 RAE) Average intake meets RDA Much stored in the liver Vitamin A supplements are
unnecessary No separate RDA for carotenoids
Effect of Vitamin A
Hypervitaminosis A: Toxicity of Vitamin A
Acute toxicity Ingestion of LARGE dose(s) of vitamin A
(within a short period) Causes intestinal upset, headache, blurred
vision, muscular incoordination, dizziness, death by convulsions
Chronic Large intake of vitamin A over a long period
(10X RDA) Bone/muscle pain, loss of appetite, skin
disorders, headache, dry skin, hair loss, increased liver size, vomiting; dry itchy & flaky skin, fructures
Hypervitaminosis A: Toxicity of Vitamin A
Teratogenic Produce physical defect on developing fetus Spontaneous abortion, birth defects May occur with as little as 3 x RDA of
preformed vitamin AUpper Level for Vitamin A 3000ug for adultsFatal dose -12 g of vitamin A can be fatal
Toxicity of Carotenoids
Hypercarotenemia High amounts of carotenoids in
the bloodstream Excessive consumption of
carrots/squash/beta-carotene supplements
Skin turns a yellowish-orange color
Vitamin D: sources
Sun exposure to skinSynthesized from cholesterol- cholecalciferol
Classified as a prohormone
DietFortified milk & cereal
Vitamin D Synthesis
Vitamin D synthesis
Liver hydroxylase Catalyzed conversion formation of
provitamin D: 25-OH vitamin D Kidney: Kidney hydroxylase
produces 1,25 dihydroxycholecalciferol (1,25 vit D)
Also called Calcitrol; active hormone form Kidney main site of vit D formation
Functions of Vitamin D Regulates blood Ca levels
Increase absorption of Ca and P Changes resorption of Ca and P in kidneys
Causes Ca & P to deposit in bone Strengthens bone-bone mineralization Causes differentiation of osteoclast into
osteoblasts for new bone formation Maintains function of neuromuscular
junctions Reduces cancer cell proliferation by
inducing differentiation
Vitamin D
DeficienyRickets in childrenOsteomalacia (soft bone) and osteoporosis in adults
ToxicityHypercalcemia
The Adequate Intake (AI) for Vitamin D
5 ug/d (200 IU/day) for adults under age 51
10-15 ug/day (400 - 600 IU/day) for older Americans
Infant are born with enough vitamin D to last ~6 months of age.
Vitamin D as a Medicine
Type II (age-related) osteoporosis Loss of bone mass due to limited ability
to absorb vitamin D or produce calcitriol 10-20 ug vitamin D/ day plus calcium
decrease bone fracture Risk for hypercalcemia
Psoriasis Skin disorder Topical treatment
Toxicity Warning Occurs at 5-10x the AI
Upper level is 50ug/d Result from excess supplementation (not from sun
exposure or milk consumption) Sign and symptoms:
Over absorption of calcium (hypercalcemia), increase calcium excretion
Soft tissue calcification Calcium deposits in kidneys, heart, and blood
vessels Mental retardation in infants Renal lethiasis (Ca stones )
Vitamin E: Functions Refers to a family of compounds
called Tocopherols and tocotrienols
Antioxidant; donates electron to oxidizing agent Prevents increase in free radicals Protect the cell from attack by free
radicals Protects PUFAs within the cell
membrane and plasma lipoproteins Prevents the alteration of cell’s DNA
and risk for cancer development
FunctionsExamples of free radicals
Peroxyl-radical-a lipid radical from breaking of FA chains, has an unpaired electron
Reactive oxygen species (ROS) from chemical pathways that make ATP
Functions May prevent oxidation of Vitamin A May have a role in the synthesis of
Hemoglobin or May activate enzymes in the
mitochondria to improve O2 utilization
Other antioxidants
Glutathione peroxidaseSuperoxide dismutaseCatalase
Food Sources of Vitamin E
Plant oils Wheat germ Asparagus Peanuts, nuts & seeds Margarine, shortenings, salad
dressing, oils Nuts and seeds Actual amount is dependent on
harvesting, processing, storage and cooking
RDA for Vitamin E15 mg/day for women and menRecommendation prevents
hemolysis of RBC
Deficiency of Vitamin E
Hemolytic anemia, why? Peripheral neuropathy-damage to
nerve cells Insufficient bile production May contribute to heart disease,
cancer, premature aging and decreased fertility
Rare
Toxicity of Vitamin E Supplements up to 800 IU is probably
harmless Upper Level is 1,000 mg/day of any
form of supplementary alpha-tocopherol
Upper Level is 1500 IU (natural sources) or 1100 IU (synthetic forms)
Inhibit vitamin K metabolism and anticoagulants
SUPPLEMENTATION:
One study by Kobyoshi found that 1200 IU daily for 6 weeks in non-athletes:
Improved max VO2 Reduced Blood Lactic Acid during submaximal
exercise Increased aerobic endurance at altitudes
between 5,000 and 15,000 feet. Theory was to prevent oxidation of RBC membranes
that might occur at altitude Research needed on athletes
May improve endurance in athletes exercising in high-smog areas.
Athletes should take between 100-200 IU per day, however there is a lack of conclusive evidence of a beneficial effect.
Vitamin K (“Koagulation”)
Phylloquinone (K1) and menaquinones (K2)
Classified as Fat soluble Blood Coagulation Vitamin or Anti-hemorrhagic Vitamin
Menaquinones are synthesized by the bacteria in the colon and are absorbed
Function of Vitamin K
Formation of Four compounds essential to two steps of blood clotting
Enhances function of OSTEOCALCIN, a protein with an important role in strengthening bones
Calcium-binding potential
Drugs and Vitamin K
Anticoagulant Lessens vitamin K reactivation Lessens blood clotting process
Antibiotics Destroy intestinal bacteria Inhibits vitamin K synthesis and
absorption Potential for excessive bleeding
Vitamin K Deficiency
Impares blood clotting and leads to hemorrhage
May effect Kidney excretion of Calcium and may be involved in osteroporosis.
Rare, however may occur due to antibiotic medications that kill intestinal bacteria
Food Sources of Vitamin K
Liver Egg yolk Milk Green leafy vegetables Broccoli Peas Green beans
Adequate Intake for Vitamin K
90 ug/day for women 120 ug/day for men RDA met by most Excess vitamins A and E interferes
with vitamin K Newborns are injected with vitamin
K(breast milk is a poor source) Toxicity unlikely; readily excreted
SUPPLEMENTATION:
No supplementation studies No evidence that supplementation
would improve health status or athletic performance.
Supplements only available by prescription
Water Soluble Vitamins NINE WATER SOLUBLE VITAMINS B-complex:
B1 Thiamin B2 Riboflavin B6 Pyridoxine, pyridoxal, pyridoxanine B12 Cobalamin, cyanocobalamin Niacin Biotin Folic Acid Pantothenic Acid
C Ascorbic Acid
THIAMIN (VITAMIN B1)
RDA: Adult males, 1.5 mg/day Adult females, 1.1 mg/day
SOURCES: Whole grain cereals Beans Seeds, Nuts Pork Fruits and Vegetables Limited synthesis by bacteria in
intestine
Functions
Central role in the metabolism of Glucose
Part of the coenzyme thiamine pyrophosphate needed to convert pyruvate to acetyl CoA for entrance into the Krebs Cycle
Normal functioning of the Nervous System
Energy derivation from glycogen in the muscles
DEFICIENCY
Symptoms occur in several weeks 1. loss of appetite 2. mental confusion 3. muscular weakness 4. pain in calf muscles 5. prolonged deficiencies lead to Beriberi –
damage to nervous system and heart Rare, but more common in alcoholics,
homeless, and other special groups Exercise and high carbohydrate intake
increases need for Thiamin
SUPPLEMENTATION:
No ergogenic effect (Increase in muscular work
capacity) if taken beyond RDA Japanese research showed fewer
subjective complaints of fatigue following strenuous exercise with thiamin supplementation
Megadoses up to 1000 mg showed no adverse effect.
RIBOFLAVIN (VITAMIN B2)
RDA: Adult male, 1.7 mg/day Adult female, 1.3 mg/day
SOURCES: Milk and Dairy Products Liver Eggs Dark-green Leafy Vegetables Wheat Germ Yeast Whole-grain products Enriched breads and cereals
METABOLIC FUNCTION:
Formation of several oxidative enzymes known as flavoproteins
Flavoproteins involved in energy production from Carbohydrate and Fats in the body cells
Involved in Protein metabolism Maintenance of healthy skin
DEFICIENCY:
Glossitis – inflammation of tongue Cracks at the corners of the mouth Dry, scaly skin at corners of the nose SUPPLEMENTATION:
Untrained women initiating an aerobics program may need higher intake of Riboflavin to synthesize more flavoproteins; Early stages of training need about 1.1 mg/1000 kcal
Research shows no ergogenic effect Megadoses offer no adverse effects
NIACIN
RDA: Adult Males, 19 NE (Niacin
equivalents) Adult Females, 15 NE About 6.6 mg/1000 kcal intake 1 NE = 1 mg of Niacin or 60 mg of
Tryptophan Excess Tryptophan is converted to
Niacin
SOURCES:
Lean Meats Organ Meats Fish Poultry Whole-grain cereal products Legumes, such as beans and peanuts Enriched foods From Excess Tryptophan from Milk and
eggs
METABOLIC FUNCTION:
Serves as a component of a coenzyme that is important in glycolysis
Serves as a component of a coenzyme that is important in Fat metabolism
DEFICIENCY:
Enrichment of foods has nearly eliminated deficiency
Symptoms Loss of appetite Skin rashes Mental confusion Lack of energy Muscular weakness Serious deficiencies lead to Pellagra
severe dermatitis Diarrhea symptoms of mental illness
SUPPLEMENTATION:
Not an ergogenic aid Supplements may reduce endurance
capacity if over 3-4 gm/day Can block the release of FFA from
adipose and increase dependence on Carbohydrate
May increase blood flow to the skin as in a histamine reaction, but this could also result in loss of body heat during exercise and subsequent reduction in sweating
SUPPLEMENTATION:
Megadoses: May reduce serum cholesterol levels of
Total and LDL, and lower Triglycerides (not a recommended treatment)
May raise HDL levels in blood May cause histamine like effect May contribute to liver problems;
hepatitis and peptic ulcers May impair athletic performance
VITAMIN B6 (PYRIDOXINE)
Pyroxidine is used collectively for Pyroxidine, pyridoxal, pyridoxamine
RDA: Adult, 2 mg/day Based on Protein intake with higher RDA for Higher
Protein intakes. SOURCES:
Meats Poultry Fish Wheat Germ Whole-grain products Brown Rice Eggs
VITAMIN B6 (PYRIDOXINE)
Make coenzyme, pyridoxal phosphate (PLP) that transfers amino acids, to make non-essential AA
Metabolism of Fat and CHO Functions with > 60 enzymes for processes that
include: Synthesis of dispensible Amino Acids Conversion of Tryptophan to niacin Formation of Neurotransmitters Incorporation of Amino Acids into body protein:
Hemoglobin Myoglobin Oxidative enzymes
Breakdown of muscle glycogen Gluconeogenesis in the Liver
DEFICIENCY: Not a major health problem
Alcohol interacts with Vitamin B6 Destroys and makes it unavailable to the body The drug INH prescribed to treat tuberculosis
acts as an antagonist to the vitamin May occur with the use of diuretics and oral
contraceptives Symptoms:
Nausea Impaired Immune Function Skin Disorders Weakness Mental Depression Anemia
Vitamin B12 Cobalamin
Close relationship between vitamin B12 and folate Depend on each other for activation
Microwave cooking destroys B12 Intrinsic factor:
The HCL and pepsin in the stomach release B12 from the protein foods to which it is attached
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