VITAMIN C

1. M R . A . A j i t h M . s c . , D M L T .
L e c t u r e r
S r i V e n k a t e s w a r a a U n i v e r s i t y
E t t a y a p u r a m
WATER SOLUBLE
VITAMINS

2.  There are about 15 vitamins, essential for humans.
They are classified as fat soluble (A, D, E and K)
and water soluble
 Water soluble vitamins are classified as two types
 B – complex
 Non B –complex
 The B-complex vitamins may be sub-divided into
energy-releasing (B1, B2, B6, biotin etc.) and
hematopoietic (folic acid and B12).

3. Non –B complex
 Vitamin c (Ascorbic acid)
 Vitamin C is a water soluble versatile vitamin.
 It plays an important role in human health and
disease.
 Scurvy
 Scurvy is a disease resulting from a lack of vitamin
C (ascorbic acid)
 decreased red blood cells
 Weakness, feeling tired, changes to hair, easy
bleeding

5.  Ascorbic acid is a hexose (6 carbon) derivative and closely
resembles monosaccharide's in structure.
 The acidic property of vitamin C is due to the enolic
hydroxyl groups.
 It is a strong reducing agent. L-Ascorbic acid undergoes
oxidation to form dehydroascorbic acid and this reaction
is reversible.
 vitamin C – specifically, in the form of ascorbate – performs
numerous physiological functions in the human body by
serving as an enzyme substrate or cofactor and an electron
donor.
 These functions include the synthesis of collagen, carnitine,
and neurotransmitters; the synthesis and catabolism of
tyrosine; and the metabolism of microsomes.

6. BIOSYNTHESIS AND METABOLISM
 Many animals can synthesize ascorbic acid from
glucose via uronic acid pathway.
 It is not stored in the body to a significant extent.
 Ascorbic acid is excreted in urine as such, or as its
metabolites— diketogulonic acid and oxalic acid
 Man, other primates, guinea pigs and bats cannot
synthesize ascorbic acid due to the deficiency of a
single enzyme namely L- gulonolactone oxidase

7. 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
 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).
 Bone formation : Bone tissues possess an organic
matrix, collagen and the inorganic calcium, phosphate
etc. Vitamin C is required for bone formation

8.  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. It helps in the formation of
ferritin (storage form of iron) and mobilization of
iron from ferritin
 Tryptophan metabolism
 Tyrosine metabolism
 Folic acid metabolism
 Peptide hormone synthesis

9.  Immunological function : Vitamin C enhances the
synthesis of immunoglobulins (antibodies) and
increases the phagocytic action of leucocytes
 Preventive action on chronic diseases : As an
antioxidant, vitamin C reduces the risk of cancer,
cataract, and coronary heart diseases

10. RDA
 Women -75 milligrams (mg)
 Men -90 milligrams (mg)
 Pregnancy -120 milligrams (mg)

11. DIETARY SOURCES
 Citrus fruits,
 Gooseberry (amla),
 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

12. DEFICIENCY SYMPTOMS
 The deficiency of ascorbic acid results in scurvy.
 This disease is characterized by spongy and sore
gums, loose teeth, anemia, swollen joints,
fragile blood vessels, decreased
immunocompetence, delayed wound healing,
sluggish hormonal function of adrenal cortex and
gonads, osteoporosis etc…..

13. MEGADOSES VITAMIN C
 Megadoses (1-4 g/day) of vitamin C are still
continued in common cold, wound healing,
trauma etc.
 As an antioxidant, ascorbic acid certainly provides
some health benefits.
 Ascorbic acid, as such, has not been found to be
toxic.
 Dehydroascorbic acid (oxidized form of ascorbic
acid) is toxic