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 DDeficieny

Rickets 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 MedicineType 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