Vitaminslecture 2

Presented By: Ebtesam Al-Sheddi

Fat soluble vitaminsVitamin E

The term vitamin E refers to a family of eight related compounds, the tocopherols and the tocotrienols

The four major forms of vitamin E are designated , that have varying levels of biological activity

Alpha- (or α-) tocopherol is the most active form

Termed an antioxidant

Protects cell membranes and other fat-soluble parts of the body (LDL cholesterol) from oxidation May reduce the risk of heart disease May also discourage development of some types of

cancer Promotes normal growth and development Promotes normal red blood cell formation Acts as anti-blood clotting agent Plays some role in the body’s ability to process

glucose Also been known to aid the process of wound healing

Vitamin E

Sources Plant sources

Cereal grains wheat germ oil, almonds, sunflower seeds,

sunflower oil, safflower oil, hazelnuts, peanut butter, peanuts, corn oil, spinach, broccoli, soybean oil, kiwi and mango. Vegetable and seed oils

Little in animal sources Beef fed high levels of vitamin E right before

slaughter to improve shelf life can be source The RDA (recommended daily allowance) for

vitamin E is 15 mg of d-alpha-tocopherol for adult men and women (1 mg of d-alpha-tocopherol is equal to 1.5 IU, so the RDA is equal to 22.5 IU).

Vitamin E Toxicity

• Wide range of safe intake compared to other fat soluble vitamins (toxicity rare)– Extreme high doses (50- to 100-fold above

recommended intakes) may affect the blood clotting effects of vitamin K and may lead to increased risk of hemorrhage

Fat soluble vitaminsVitamin K

Vitamin K2

K1, phylloquinone Chloroplasts in plants

K2, menaquinone Bacterial synthesis

K3, menadione Synthetic, water soluble form Complexed to improve

stability

Physiological Effects of Vitamin K Vitamin K serves as an

essential cofactor for a carboxylase that catalyzes carboxylation of glutamic acid residues on vitamin K-dependent proteins. These proteins are involved in:

1) Coagulation2) Bone Mineralization3) Cell growth

Coagulation

The transformation of liquid blood into a solid gel

Stops blood flow in the damaged area

Fibrin is the final protein which produces a meshwork to trap RBC and other cells

Vitamin K Dependent Coagulation Certain clotting factors/proteins require calcium to bind for

activation

Calcium can only bind after gamma carboxylation of specific glutamic acid residues in these proteins

The reduced form of vitamin K2 (vitamin KH2) acts as a cofactor for this carboxylation reaction.

These proteins are known as “Vitamin K dependent” proteins

Vitamin K Dependent Proteins

factor II (prothrombin) factor VII (proconvertin) factor IX (thromboplastin component) factor X (Stuart factor) protein C & protein S Protein Z

Clotting Cascade

Vitamin K Cycle

Glutamic Acid

Gamma Carboxy Glutamic Acid

Vitamin K

Vitamin K Epoxide

Vitamin KH2

Vitamin K DependentCarboxylase

Reductase

EpoxideReductase

Warfarin Inhibits

The best food sources of vitamin K are green leafy vegetables.

Milk and liver. Daily requirement:

Dietary Sources

Life StageAge   Males (mcg/day)

Females (mcg/day)

Infants0-6 months2.02.0

 Infants 7-12 months2.52.5

Children    1-3 years3030

Children4-8 years 5555

Children9-13 years6060

Adolescents 14-18 years7575

Adults19 years and older

12090

Pregnancy 18 years and younger 

-75

Pregnancy 19 years and older

-90

Breast-feeding 18 years and younger 

-75

Breast-feeding 19 years and older

-90

Vitamin K Deficiency

Results in impaired blood clotting and, potentially, bleeding.

Vitamin K deficiency can result from:

a lack of vitamin k in the diet disorders that reduce fat absorption Taking certain drugs, including anticonvulsants and some antibiotics Use of coumarin anticoagulants Salicylates Large doses of vitamin E Hepatic insufficiency

Symptoms of Vitamin K Deficiency

• Bruising from bleeding into the skin• Nosebleeds• Bleeding gums• Bleeding in stomach• Blood in urine• Blood in stool• Tarry black stool• Extremely heavy menstrual bleeding• In infants, may result in intracranial hemorrhage

Vitamin K Deficiency in InfantsNewborns are prone to vitamin K deficiency because…

1. Vitamin K and lipids are not easily transported across the placental barrier

2. Prothrombin synthesis in the liver is an immature process in newborns, especially when premature.

3. The neonatal gut is sterile, lacking the bacteria that is necessary in menaquinone synthesis.

4. Breast milk is not a good source of vitamin K

Results in a hemorrhagic disease called vitamin K deficiency bleeding (VKDB)

This disease is associated with breastfeeding, maladsorption of lipids, or liver disorders.

Vitamin K - Toxicity

Not common except with over-supplementation Phylloquinone and menaquinone are relatively

nontoxic Jaundice; brain damage

Menadione toxic to skin and respiratory tract in high doses

VITAMIN CVITAMIN C L-ascorbic acid, ascorbateL-ascorbic acid, ascorbate Synthesized from glucose by most animalsSynthesized from glucose by most animals Vitamin C is an electron donorVitamin C is an electron donor

FUNCTIONS OF VITAMIN CEnhances absorption of iron reduces iron to more absorbable

ferrous form chelates with ferrous ion to make it

more soluble

FUNCTIONS OF VITAMIN C Involved in the biosynthesis of the Involved in the biosynthesis of the

protein, collagen, found in connective protein, collagen, found in connective tissues such as cartilage, ligaments, and tissues such as cartilage, ligaments, and tendonstendons

FUNCTIONS OF VITAMIN CBiosynthesis of the Biosynthesis of the

catecholamine norepinephrine catecholamine norepinephrine (neurotransmitter)

Bile acid synthesisBile acid synthesis

OTHER FUNCTIONSOTHER FUNCTIONS

Promotes the healing of cuts, abrasions and Promotes the healing of cuts, abrasions and

woundswounds Helps fight infections. Helps fight infections. Inhibits conversion of irritants in tobacco smokeInhibits conversion of irritants in tobacco smoke

and certain foods into cancer-causing substances. and certain foods into cancer-causing substances. Appears to dilate blood vessels and thereby Appears to dilate blood vessels and thereby

lessen the risk of developing high blood pressure lessen the risk of developing high blood pressure

and heart disease. and heart disease. Helps regulate cholesterol levels. Helps regulate cholesterol levels.

FOOD SOURCES OF VITAMIN C

Citrus fruits Potatoes Green peppers Cauliflower Broccoli Strawberries Romaine lettuce Spinach

Easily lost through cooking

Sensitive to heat Sensitive air

DAILY REQUIREMENTSDAILY REQUIREMENTS

Recommended Recommended Dietary Allowance Dietary Allowance

mg per day mg per day

adult maleadult male9090

adult femaleadult female7575

Children 4-13 yearsChildren 4-13 years2525

Tolerable Upper Intake Tolerable Upper Intake Level(adult male)Level(adult male)

2,000 mg per day 2,000 mg per day

Tolerable Upper Intake Tolerable Upper Intake Level(adult female)Level(adult female)

2,000 mg per day2,000 mg per day

DEFICIENCY OF VITAMIN CDEFICIENCY OF VITAMIN C When there is a shortage of Vitamin C, When there is a shortage of Vitamin C,

various problems can arise like :various problems can arise like : Scurvy disease Scurvy disease ;;a disease characterized a disease characterized

by weakness, fatigue, anemia, swollen by weakness, fatigue, anemia, swollen joints, bleeding gums and loose teeth joints, bleeding gums and loose teeth and skin discoloration due to "pinpoint" and skin discoloration due to "pinpoint" hemorrhages under the skin and a hemorrhages under the skin and a tendency to bruise easilytendency to bruise easily

poor wound healingpoor wound healing Edema (water retention) Edema (water retention) weakness, a lack of energyweakness, a lack of energy poor digestionpoor digestion painful joints painful joints bronchial infection and colds . bronchial infection and colds .

DEFICIENCY OF VITAMIN CDEFICIENCY OF VITAMIN C

TOXICITY TOXICITY

DiarrheaDiarrhea nauseanausea skin irritationskin irritation burning upon urinationburning upon urination depletion of the mineral copper.depletion of the mineral copper. development of kidney stones development of kidney stones due to due to

oxalate formation or hemochromatosis or oxalate formation or hemochromatosis or other diseases related to excessive iron other diseases related to excessive iron accumulation.accumulation.

Thank you!