Vitamin C introduction, Chemistry of Vitamin C, Biochemical Role of Vitamin C, (Collagen formation, Bone formation, Immunological response, Synthesis of Catacholamines, ), Recommended dietary Allowance of Vitamin C, Dietary Sources of Vitamin C, Deficiency symptoms of Vitamin C, Food preparation to retain Vitamin C.

1. Chemistry and Biochemical Role, RDA and
Deficiency symptoms of Vitamin C

3. Vitamin C - Introduction
• Vitamin C is a water soluble versatile
vitamin.
• It plays an important role in human health
and disease.

5. Vitamin C - Chemistry
• Ascorbic acid is a hexose (6 carbon ) derivative and
closely resembles monosaccharides in structure.
• The acidic property of vitamin C is due to the enolic
hydroxyl groups.
• It is a storing reducing agent, L-Ascorbic acid
undergoes oxidation to form dehydroascorbic acid and
this reaction is reversible.

7. Vitamin C - Chemistry
• On hydration, dehydroascorbic acid is irreversibly
converted to 2, 3-diketogulonic acid which is inactive.
• Oxidation of Ascorbic acid is rapid in the presence of
copper.
• Hence vitamin C becomes inactive if the foods are
prepared in copper vessels

11. Ascorbic acid ( Vitamin C)

13. Vitamin C – Biosynthesis and
Metabolism
• Many animals can synthesise ascorbic acid
from glucose via uronic acid pathway.
• However, man, other primates, guinea pigs and
bats cannot synthesis ascorbic acid due to the
deficiency of a single enzyme namely
L-gluconolactone oxidase.

15. Vitamin C – Biochemical Functions
• Most of the functions of vitamin C are related
to its property to undergo reversible oxidation
-reduction i.e., interconversion of ascorbic
acid and dehydroascorbic acid.

16. Vitamin C – Biochemical Functions
I. Collagen formation: Vitamin C plays the role of a
coenzyme in hydroxylation of proline and lysine while
protocollagen is converted to collagen (i.e., Post
translational modification).
• Hydroxyproline and hydroxylysine are essential for the
collagen cross-linking and the strength of the fiber.
• In this way, vitamin C is necessary for maintenance of
normal connective tissue and wound healing process.

18. Vitamin C – Biochemical Functions
II. Bone formation: Bone tissues possess an organic
matrix, collagen and the inorganic calcium, phosphate,
etc. Vitamin C is required for bone formation.
III. Iron and Hemoglobin metabolism: Ascorbic acid
enhances iron absorption by keeping it in the ferrous
form. This is due to the reducing property of vitamin C.

19. Vitamin C – Biochemical Functions
IV. Tryptophan metabolism: Vitamin C is
essential for the hydroxylation of tryptophan
(enzyme hydroxylase) to hydroxy tryptophan
in the synthesis of serotonin.

20. Vitamin C – Biochemical Functions
V. Synthesis of corticosteroid hormones:
Adrenal gland possess high levels of ascorbic
acid, particularly in periods of stress, it is
believed that vitamin C is necessary for the
hydroxylation reactions in the synthesis of
corticosteroid hormones.

21. Vitamin C – Biochemical Functions
VI. Sparing action of other vitamins: Ascorbic
acid is a strong antioxidant. It spares Vitamin A
and Vitamin E, and some B complex vitamins
from oxidation.
VII. Immunological function: Vitamin C enhances
the synthesis of immunoglobulins (antibodies)
and increases the phagocytic action of leucocytes.

22. Vitamin C – Biochemical Functions
VIII. Preventive action on chronic diseases: Free radicals are
constantly produced in the normal metabolism.
 They cause serious damage to proteins, lipids, DNA
and the cell membranes.
 The free radicals are implicated in the development of
cancer, heart diseases and also ageing.
 Vitamin C is a strong biological antioxidant, besides
vitamin E and β-carotene.

23. Vitamin C - RDA
• About 60-70mg vitamin C in take per day will
meet the adult requirement.
• Additional intakes (20-40% increase) are
recommended for women during pregnancy
and lactation.

24. Vitamin C – Dietary Sources
• Citrus fruits, gooseberry (amla), guava, green
vegetables (cabbage, spinach), tomatoes, potatoes
(particularly skin) are rich in ascorbic acid.
• High content of vitamin C is found in adrenal
gland and gonads.
• Milk is a poor source of ascorbic acid.

25. Vitamin C – Deficiency symptoms
• The deficiency of ascorbic acid results in scurvy.
• This disease is characterized by:
• spongy and sore gums,
• loose teeth,
• anemia,
• swollen joints,
• decreased immunocompetence,
• delayed wound healing,
• haemorrhage,
• osteoporosis, etc.