Ppt on fat soluble vitamin A History, process, sources, requirements, effective and hyper

1. FAT SOLUBLE VITAMIN- A
Laxman I
1ST MSc BIOTECH

2. Vitamins
• Vitamins are the organic compounds
required in the diet in small amounts in
different natural foods
• Necessary for the growth and maintenance
of good health.
• Daily requirement depends on the age group
and increase during growth, pregnancy and
lactation.

3. “A Vitamin is a substance that makes
you ill if you don’t eat it”
-Albert Szent-Gyorgyi, Nobel Prize winner, 1937

4. CLASSIFICATION OF VITAMINS:
• There are about 15 vitamins, essential for humans

5. VITAMINS
CHARACTERISTICS FAT SOLUBLE
VITAMINS
WATER SOLUBLE
VITAMINS
1 Solubility Fat soluble Water soluble
2 Absorption Bile salts are
required
Simple intestinal
absorption
3 Transportation Transported by
carrier protein
No protein is
required, travels
freely
4 Storage In liver and fat
tissues
Not stored
5 Excretion Surplus vitamins
are stored
Surplus vitamins are
detected and
removed in urine
6 Requirement Required in
periodic doses
Required in frequent
doses

6. VITAMIN- A
•Vitamin A is an essential micronutrient for humans, meaning
that it cannot be biosynthesized in the body and thus must be
obtained from dietary sources.
•Vitamin A is a collective name for a group of lipophilic
biomolecules required by humans to perform different vital
metabolic functions like vision, repair, reproduction, growth
and tissue differentiation.
•The vitamin exists in three Major forms: retinal, retinol and
retinoic acid.

7. HISTORY
• It is recorded in history that Hippocrates cured night blindness(about 500 b.c)
• He prescribed to the patients ox liver(in honey)which is now known to contain
high quantity of vitamin a.
•
• By 1917, Elmer McCollum et al,. at the university of Wisconsin-Madison,
studied the role of fats in the diet and discovered few accessory factors. These
“accessory factors” were termed “fat soluble” in 1918 and later “vitamin A” in
1920.
• In 1919, Harry Steenbock (University of Wisconsin) proposed a relationship
between yellow plant pigments (beta-carotene) and vitamin A.
• In 1931, Swiss chemist Paul karrer described the chemical structure of vitamin
A.
• Vitamin A was first synthesized in 1947 by two Dutch chemists, David Adriaan
van Dorp and Jozef Ferdinand Arens.

8. Chemistry:
• Vitamin A is fat soluble. The active form is present
only in animal tissues.
• The provitamin, beta-carotene is present in plant
tissues.
Three different compounds with vitamin A activity
1. Retinol (vitamin-A alcohol )

9. 2. Retinal (vitamin-A aldehyde)
3. Retinoic acid (vitamin-A acid)

10. WALDS VISUAL CYCLE
• The term Visual cycle was coined by George Wald in the
mid 1900’s
• To describe the ability of eye to “re-cycle” Vitamin A for the
synthesis of visual pigments
• Wald was awarded Nobel prize in 1967 for identifying role
off Vitamin A in vision.
• Process of visual information begins in the retina with the
detection of light by photoreceptor cells.
• Photoreceptors involved in the vision are rods and cones.
• Rhodopsin (mol.wt 35,000) is a membrane protein present
in the photoreceptor rod cells of retina.

11. WALDS VISUAL CYCLE

12. BIOLOGICAL FUNCTIONS OF
VITAMIN-A
• They regulate protein synthesis.
• Function as steroid hormones.
• To maintain healthy epithelial tissue
• Involved in the cell growth
• Required to prevent keratin synthesis
• Necessary for normal reproduction

13. BIOLOGICAL FUNCTIONS OF
VITAMIN-A
• Maintenance of proper immune system to
fight against various infections.
• Cholesterol synthesis
• Function as antioxidants

14. Recommended dietary
allowance (RDA)
 The daily requirement of vitamin A is expressed as retinol
equivalents (RE) rather than International Units (IU).
 The recommended daily allowance (RDA) for
• Children = 400–600 mcg/day • Men = 750–1000 mcg/day
• Women = 750 mcg/day • Pregnancy = 1000 mcg/day
 One international unit = 0.3 mcg of retinol.
 One retinol equivalent = 1 ug of retinol or 6 ug of beta
carotene.

15. SOURCES
Plant sources: sweet potatoes, carrots, pumpkins,
papayas, tomatoes and leafy green vegetables
which supply pro vitamin A (carotene) in the diet.
Cereals also contain carotene.
Animal sources: Preformed vitamin A (retinol) is
supplied by foods of animal origin; they are liver,
milk, butter, eggs. Kidney, the fat of muscle, meats,
and fish. Liver oil which is very rich in the vitamin.

16. VITAMIN ‘A’ DEFICIENCY
The vitamin A deficiency may be due to
inadequate dietary intake, impaired intestinal
absorption, reduced storage in liver and chronic
alcoholism.
• Effect on eyes: leads to xerophthalmia
• Effect on growth
• Effect on reproduction
• Effect on skin and epithelial cells

17. Hypervitaminosis A
Excessive consumption of vitamin A leads to toxicity
The symptoms of hypervitaminosis A
• Dermatitis raised intracranial tension
• Enlargement of liver
• Skeletal decalcification
• Tenderness of long bones
• Loss of weight
• Irritability
• Loss of hair
• Joint pains

18. References
1. Berg.J M, Tymoczko.J L, Stryer L [2007] Biochemistry. Seventh
Edition. W.H.Freemann And Company. USA. PP: 423-425
2. Deb. A C [1983] Fundamentals of Biochemistry Ninth Edition,New
Central Book of Agency . Kolkata, India. PP: 210-216
3. Delvin. T.D [2011] Textbook of Biochemistry Seventh Edition. PP:
1066-1067
4. Jain.J.L, Jain.S, Jain.N, [2005] Fundamentals of Biochemistry.
Seventh edition. S.Chand And Comapany, New Delhi. PP: 966-972
5. Kumar. P, Mina U. [2021] Life sciences Fundamentals and Practice
01, Seventh Edition, Pathfinder Publication. New Delhi, India. PP:
104-105
6. Nayak.S.B [2011] Essentials of Biochemistry. Jaypee Brothers
Medical Publishers, New Delhi. PP: 241-243
7. Nelson.D, Cox.M, Aoskins.A [2021] Lehninger Principles of
Biochemistry. Eighth Edition. W.H.Freeman And Comapany. New
Delhi. PP: 1329-1334