Vitamin A deficiency can lead to several health issues: 1) It can cause night blindness and poor vision due to inflammation of the eye. 2) It suppresses the immune system and increases risk of infections like colds. 3) Severe deficiency can cause xerophthalmia, a dryness of the eye, and keratomalacia, a softening and ulceration of the cornea.

1. VITAMIN A DEFICIENY
AND
ITS IMMUNE RESPONSE

2. Submitted by
T.Tamil selvan .

3. INTRODUCTION :
The ancient Egyptians as
mentioned in the “PAPYRUS EBERS” that juice
obtained from cooked liver should be applied to eye
to cure eye diseases mostly night blindness.
 Vitamin A activity of carotenoids was discovered
by Stunbock -1919.
 Structure of vitamin A was determined by Karrer
- 1931.
 Synthesis in lab by Kuhn and Morris – 1937.

4. Due to its role in visual process it is often called as
“Antixerophthalmic factor” or “Bright eyes ” vitamin .
Properties :
 Retinol is a Viscid , colorless oil.
 It is soluble in fat and fat solvents ,but insoluble
in water.
 It is destroyed on exposure to UV light.

5.  Vitamin A is found in two forms A1 and A2.
 Carotenoids are the precursors of Vitamin A.
 Carotenoids that give rise to vitamin A in animal
body is called as provitamin A.
 Beta-carotene is the most potent of all those
forms.
 Vitamin A1 is a complex primary alcohol called
Retinol .

6. DEFICIENCY SYMPTOMS :
 Prolonged deficiency of vitamin A may result in
Inflammation of the eye , Poor vision and night
blindness.
 There is an increased susceptibility of infections
especially of the respiratory tract in the form of
frequent and common colds .
 Vitamin A deficiency leads to lack of appetite ,
defective gums and tooth , skin disorders such as
pimples , acne , boils and premature wrinkles.

7.  It include retorted growth in children , dry and dull
hair , dandruff , Exclusive hair loss , ridged nails
and poor sense of taste and smell .
 Vitamin A is an important factor in Tooth formation.
In its deficiency there is a defective formation of
enamel so that the dentin is exposed. So that
sound tooth formation does not occur.
 The symptoms of vitamin A are not immediate .

8. DEFICIENCY MANIFESTATION OF EYES :
NYCTOLOPIA :
 one of the earliest symptoms of vitamin A
deficiency .
 The individuals have difficult to see in Dim light.
Since the dark adoption time is increased.
 Prolonged deficiency irreversibly damages a
number of visual cells.

10. xerophthalmia :
 Severe deficiency causes xerophthalmia .
 This causes dryness in conjunctiva and cornea
and keratinization of epithelial cells .In certain
areas of conjunctiva while triangular plaques
known as Bitot’s spots are seen.

12. Keratomalacia :
 kerata = hair ; malakia = softness .
 It is a corneal disease .
 occurs maximally in pre – school children of age
3-4 years.
 It suddenly happens in young children with
kwashiorkor .
 At first the cornea loses its luster , undergoes
necrosis and later to form a large , white ulcerative
area .
 In case of extensive ulceration the whole eyeball
may shrink .

14. Phrynoderma :
 It is a skin lesion caused by hyperkeratosis .
 The skin on the outer aspects of forearms in the
regions of the elbows and the thighs and become
rough and spiky.
 In the alimentary tract , the deficiency of vitamin
A causes damage to the Intestinal mucosa ,
resulting in diahorrea .

16. Hypervitaminosis A :
 Excessive consumption of vitamin A leads to
toxicity .
 The symptoms include dermatitis , enlargement
of liver , skeletal decalcification , loss of weight ,
irritability , loss of hair .
 The subject have constant head ache , due to
intercranial pressure which resembles the
symptoms of brain tumor.

17.  Ingestion of high quantities of vitamin A by
pregnant women is associated with the risk of
congenital malfunction in the developing fetus.

18. Effect on growth :
It results in growth retardation due to
impairment in skeletal deformation .
Effect on Reproduction :
The reproductive system is adversely
affected in vitamin A deficiency.
Degeneration of germinal epithelial
cells leads to Sterility in males .

19. Effect on skin :
 The skin becomes rough and dry.
 Vitamin A deficiency is associated with formation
of urinary stones .
 Keratinization of epithelial cells of Gastro -
intestinal tract , urinary tract , respiratory tract is
noticed .
 This leads to increased bacterial infection .

20. Vitamin A and vision :
 The biochemical function of vitamin A in the
process of vision was first explained by George
Wald ( Noble prize 1968 ) .
 The process is known as Rhodopsin cycle or
Wald’s visual cycle .
 The retina of Human eye posses two types of
cells – Rods and Cones. ( Rhodopsin and
Photopsin ) .

21. RODS CONES
10 million rods are
present.
5 million cones are
present.
Rods present in
periphery.
Cones at the center of
retina.
Involve in dim light vision. Involves in bright light
vision.

23. Chemical cycle :
Beta – carotene.
Retinol opsin ( Visual )
Retinal Retinyl phosphate
Retinoic acid

25. Retinoid - Includes natural and synthetic forms
of vitamin A.
Rich dietary sources :
Animal origin :
sheep liver , egg yolk , whole
milk , butter and ghee. Liver oils of various fishes are
rich in vitamin A.
Vegetables :
beet , carrot , spinach etc..
contain lot of carotene .
Fruits :
Mangoes , apricots , oranges ,
etc.

27. Dietary requirements :
 Infants - 350 -500 µg
 1-6 yrs. - 400 µg
 7-12 yrs. - 500 µg
 Adults - 600 µg
 Men - 600 - 900 µg
 Women - 600 - 900 µg
 Pregnant - 700 - 800 µg
 Lactating - 1100 – 1300 µg