Download Vitamin A deficiency

Community Medicine
Lecture -5-
Learning objectives
At the end of this lecture student would be able to :
1-Determine vitamins general characteristics .
2-Classify vitamins .
3-Determine essential facts about vitamins A,E,K & B
complex .
4-Outline clinical presentation of vitamin A deficiency &
toxicity .
5-Identify directions of action of vitamin D , clinical
features of vitamin D deficiency .
6-Discuss clinical presentation of vitamins
B1,B2,nicotinic acid , folic acid , B12 , & vitamin C
deficiency .
Vitamins
Vitamins are group of organic compounds that are
needed in small amounts for maintaining normal
metabolism of nutrients and thus promoting the
physiological well being of human body.
 It cannot be synthesized by human body.
 Vitamins vary in their composition and functions.
 Its presence in various kinds of food is in a variable
amounts.
 No optimal food is present i.e. there is no food that
contain all essential vitamins to satisfy the daily
requirement .
 Vitamins are usually required in a relatively small
quantities.
 Vitamins Primarily have a catalytic function i.e. it
enter in the enzymatic system components which
play an important role in facilitating essential
metabolic reactions.
Causes of vitamin deficiency
A- Decreased intake including :
1- alcohol intake
2- small bowel diseases
B-Decreased absorption including :
1- disease due to liver or biliary tract
2- bacterial overgrowth in the intestine
Causes of vitamin deficiency/ cont
C- Miscellaneous including :
1- Renal diseases
Classification
According to its solubility , vitamins are classified in
to :A-) Fat soluble vitamins
It include vitamins A,D,E and K.
Vitamin A (Retinol)
 Although vitamin A can be destroyed easily by
oxidation ,it is relatively heat stable material.
 To a great extent , it is found naturally in its
precursors form i.e. carotenoid pro-vitamins alpha,
beta and gamma carotene .

 Sources are liver , dairy products ,eggs ,green
vegetables and carrot . Fish liver is the most
concentrated natural source.
Importance of vitamin A
1.It is necessary for the growth of children.
2.It play an important role in the eyes
perception to light specially at night (rods and
cones photo receptors).
3.It has a protective function for surface
tissues e.g. respiratory tract and eye (cornea).
Other effects of vitamin A
1- possible beneficial effects
A- protection against cancer
B- reduction in cardiovascular events
2- possible adverse effects:
1- retinol is a teratogenic
Vitamin A deficiency
Clinically patient will develop:1.Night blindness i.e. poor adaptation for dark.
2.Xerosis i.e. changes in the outer layer of sclera resulting
in xeropthalmia .
3.Keratomalacia i.e. corneal affection.
4.Cutaneous lesions around the hair follicles.
5.Epithelial changes .
Vitamin A toxicity
Patient clinically will have:1.Anorexia .
2.Dry itchy skin .
3.Coarse hair.
4.Swelling over the long bones.
 The daily recommended allowances is 5000 I.U.
 Additional daily requirement is 1000 I.U. for
pregnant woman and 3000 I.U. for lactating woman.
Vitamin D
Vitamin D play a major role in increasing the utilization
and retention of calcium and phosphorus in the body.
Directions of action:1.It increase the absorption of dietary calcium and phosphorus
from intestinal lumen.
2.It reduce phosphorus excretion in urine through enhancing
renal reabsorption of it .
3.It maintain proper calcium and phosphorus levels in blood
.This will ensure normal mineralization condition for mature
bones.
Vitamin D deficiency
 In children leads to Rickets.
 In adults leads to Osteomalacia.
Thyroid hormones
Both parathyroid and calcitonin hormones with
vitamin D are concerned with maintenance of calcium
and phosphorus -plasma levels .
Sources are liver oil, fish ,egg ,milk and milk
products.
During summer ,dairy products contain more
vitamin D than during winter.
Sunlight act on skin and subcutaneous fat and help in
the oxidation and formation of vitamin D.
Vitamin E
•It has some influence on fertility.
•Sources are green vegetables, milk and milk products.
The main function of vitamin E are :
1- antioxidant properties
Vitamin E deficiency causing
1- hemolytic anemia
Vitamin K
1-It is found in green plants.
2-It Play a role in prothrombin formation Thus
it is essential for normal clotting of blood.
3-Bacterial flora of intestine synthesize vitamin
K.
Vitamin K deficiency
Vitamin K deficiency lead to defect in clotting
factor synthesis and increase in prothrombin
time resulting in hemorrhage
The deficiency occur in the following conditions
:
1- The newborn baby due to poor placental transfer of vitamin
K and its little amount present in breast milk
2- Cholestatic jaundice when there is an interruption of the bile
flow into the intestine
Vitamins B complex (vitamins B group)
Vitamin B1 (thiamine):Unstable at high temperature .
Destroyed by alkaline materials.
The main functions of vitamin B1are :
2- Thiamin pyrophosphate is involved in the oxidative
decarboxylation of acetyl CoA in mitochondria
‫مقطع مضاف‬
Vitamin B1 deficiency usually presented as :
1.Affection of children growth.
2.Neuritis.
3.Irritability and depression (psychological
symptoms)
4.Beriberi disease -------- a- wet type (in cases
of extreme deficiency)
b- dry type
Sources are seeds, green plants, potato and
milk.
B1 deficiency
Thiamin deficiency is seen :
1- As beriberi, where the only food consumed is
polished rice .
Vitamin B2 (riboflavin)
It is easily destroyed by heat, ultraviolet and
alkaline materials.
 Sources are liver, meat, eggs, and milk.
 Features of vitamin B2 deficiency are:1.Affection of children growth.
2.Cracks at corners of mouth and nose (Angular stomatitis )
3.Glossitis ( a red , inflamed tongue )
Nicotinic Acid
Niacin is necessary for fatty – acid synthesis
Niacin is lost by removing bran from cereals .
Niacin is found in plants , meat ( mainly offal ) and fish
.
Features of nicotinic acid deficiency are:
1. Affection of children growth .
2.Skin affection result in red rough skin.
3.Digestive disturbances and diarrhea.
Folic Acid
Its deficiency result in macrocytic anemia.
green vegetables and formed by intestinal Sources are liver, 
flora.
Vitamin B12
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Its deficiency lead to pernicious anemia.
Its minimal daily requirements is 0.1  gm.
Its liver store depleted in 3-6years.
Sources are liver, meat, milk, and fish.
Vitamin C
It can be easily destroyed by heat.
 Its main sources are fruits, fresh vegetables ,fresh
liver ,meat and milk.
Ascorbic acid is easily leached out of vegetables when
they placed in water
Potatoes are a good source , but vitamin C is lost during
storage .
A dose of 1-2g/ daily of ascorbic acid will prevent common cold
 Features of its deficiency include:1. Affection of children growth.
2.Bleeding around hair follicles.
.
Vitamin B6
1- It is exists as pyridoxine which is found mainly in plant
and animal foodstuffs .
2- Pyidoxal phosphate is a cofactor in the metabolism of
many amino acids
3-Some drugs like (isoniazid and penicillamine) interact with
Pyidoxal phosphate leading to B6 deficiency .
Thank You