Transcript lecture 2 413PHG

Vitamins
lecture 2
Presented By:
Ebtesam Al-Sheddi
Fat soluble vitamins
Vitamin E
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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 a, b, d, g, that have varying levels of
biological activity
Alpha- (or α-) tocopherol is the most active
form
Termed an antioxidant
Vitamin E
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Protects cell membranes and other fat-soluble parts of
the body (LDL cholesterol) from oxidation
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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
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-alphatocopherol is equal to 1.5 IU, so the RDA is equal
to 22.5 IU).
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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 vitamins
Vitamin K
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K1, phylloquinone
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K2, menaquinone
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Chloroplasts in plants
Bacterial synthesis
K3, menadione
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Synthetic, water soluble form
Complexed to improve
stability
Vitamin K2
Physiological Effects of Vitamin K
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Vitamin K serves as an
essential cofactor for a
carboxylase that catalyzes
carboxylation of glutamic
acid residues on vitamin Kdependent proteins. These
proteins are involved in:
1) Coagulation
2) Bone Mineralization
3) Cell growth
Coagulation
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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
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Certain clotting factors/proteins require calcium to bind for
activation
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Calcium can only bind after gamma carboxylation of specific
glutamic acid residues in these proteins
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The reduced form of vitamin K2 (vitamin KH2) acts as a
cofactor for this carboxylation reaction.
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These proteins are known as “Vitamin K dependent”
proteins
Vitamin K Dependent Proteins
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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
Reductase
Vitamin KH2
Vitamin K
Glutamic Acid
Vitamin K Dependent
Carboxylase
Warfarin Inhibits
Epoxide
Reductase
Vitamin K Epoxide
Gamma Carboxy
Glutamic Acid
Dietary Sources
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The best food
sources of vitamin
K are green leafy
vegetables.
Milk and liver.
Daily requirement:
Life Stage
Age
Males
(mcg/day)
Females
(mcg/day)
Infants
0-6 months
2.0
2.0
Infants
7-12 months
2.5
2.5
Children
1-3 years
30
30
Children
4-8 years
55
55
Children
9-13 years
60
60
Adolescents
14-18 years
75
75
Adults
19 years and
older
120
90
Pregnancy
18 years and
younger
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75
Pregnancy
19 years and
older
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90
Breast-feeding
18 years and
younger
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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:
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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
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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 Infants
Newborns are prone to vitamin K deficiency because…
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Vitamin K and lipids are not easily transported across the placental
barrier
Prothrombin synthesis in the liver is an immature process in newborns,
especially when premature.
The neonatal gut is sterile, lacking the bacteria that is necessary in
menaquinone synthesis.
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
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Not common except with oversupplementation
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Phylloquinone and menaquinone are relatively
nontoxic
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Jaundice; brain damage
Menadione toxic to skin and respiratory tract in
high doses
VITAMIN C
L-ascorbic acid, ascorbate
 Synthesized from glucose by most animals
 Vitamin C is an electron donor
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FUNCTIONS OF VITAMIN C
 Enhances
absorption of iron
 reduces iron to more absorbable ferrous
form
 chelates with ferrous ion to make it more
soluble
FUNCTIONS OF VITAMIN C
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Involved in the biosynthesis of the
protein, collagen, found in connective
tissues such as cartilage, ligaments, and
tendons
FUNCTIONS OF VITAMIN C
 Biosynthesis
of the catecholamine
norepinephrine (neurotransmitter)
 Bile
acid synthesis
 OTHER FUNCTIONS
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Promotes the healing of cuts, abrasions and
wounds
Helps fight infections.
Inhibits conversion of irritants in tobacco smoke
and certain foods into cancer-causing substances.
Appears to dilate blood vessels and thereby
lessen the risk of developing high blood pressure
and heart disease.
Helps regulate cholesterol levels.
FOOD SOURCES OF VITAMIN C
Citrus fruits
 Potatoes
 Green peppers
 Cauliflower
 Broccoli
 Strawberries
 Romaine lettuce
 Spinach
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Easily lost through
cooking
 Sensitive to heat
 Sensitive air
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DAILY REQUIREMENTS
Recommended
Dietary Allowance
mg per day
adult male
90
adult female
75
Children 4-13 years
25
Tolerable Upper Intake
Level(adult male)
2,000 mg per day
Tolerable Upper Intake
Level(adult female)
2,000 mg per day
DEFICIENCY OF VITAMIN C
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When there is a shortage of Vitamin C,
various problems can arise like :
Scurvy disease ;a disease characterized by
weakness, fatigue, anemia, swollen joints,
bleeding gums and loose teeth and skin
discoloration due to "pinpoint"
hemorrhages under the skin and a tendency
to bruise easily
DEFICIENCY OF VITAMIN C
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poor wound healing
Edema (water retention)
weakness, a lack of energy
poor digestion
painful joints
bronchial infection and colds .
TOXICITY
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Diarrhea
nausea
skin irritation
burning upon urination
depletion of the mineral copper.
development of kidney stones due to oxalate
formation or hemochromatosis or other diseases
related to excessive iron accumulation.
Thank you!
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