Vitamin C, also known as ascorbic acid, is a water-soluble vitamin that is essential for human health. It was historically used to treat scurvy in sailors. The document discusses the history, chemistry, structure, functions, sources, deficiency, toxicity, and recommendations for vitamin C. It plays important roles as an antioxidant and in collagen synthesis, and sources include citrus fruits, berries, peppers, and leafy greens. A deficiency results in scurvy, while toxicity is rare but may cause gastrointestinal issues.

1. VITAMIN- C
By: Anisha Sachdeva
Section-A
Roll No- 003
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2.  Scurvy was treated as a dreaded disease in the ancient
times that plagued the sailors in their voyages and no
concrete remedy was known for it. In 1747, the British
physician Lind demonstrated that oranges and lemons
could cure scurvy in sailors.
 The scientific era of Vitamin C began in 1907 when Holat
and Frolich produced scurvy in guinea pigs. The isolation
and chemical structure of Vitamin C was done by Dr
Charles King in 1932.
 The chemical name for vitamin C is ascorbic acid and it is
also known as hexuronic acid and antiscorbutic nutrient.
History

3. Chemistry
 It is a white crystalline compound with a cyclic structure containing six carbon atoms. It is synthesized from
glucose or other simple sugars by plants and animals.
 It is considered a weak acid and its molecular formula is C₆H₈O₆
 Vitamin C is highly soluble in water. In aqueous solution, it dissociates to form hydrogen ion and ascorbate
ion.
 It is stable to acid but easily destroyed by oxidation, light, alkali and heat especially in the presence of iron or
copper. It is the most easily destroyed vitamin. However, oxidation of Vitamin C is inhibited to a marked
degree in an acidic medium and when the temperature is reduced.
 The oxidized form of ascorbic acid known as dehydro-ascorbic acid also has vitamin C activity; but the
oxidation products of dehydro-ascorbic acid have no vitamin C activity.
 Vitamin C is a biological reducing agent, especially during hydroxylation reactions, and it has antioxidant
properties that protects the body against damaging oxidizing agents.
 Most mammals can synthesize Vitamin C from glucose but a few species including humans lack the liver
enzyme, L- gulonolactone oxidase to catalyse this process. Thus, they have to depend on supplies of
vitamin C from food. In plants, vitamins C accumulates during the ripening process.

4. Structure
Ascorbic acid exists as two enantiomers
(mirror-image isomers), commonly
denoted “L" (for "levo") and “D" (for
"dextro").
 The L isomer i.e., L- Ascorbic acid is the
reduced form. It is most often
encountered as it occurs naturally in
many foods.
 The “D" isomer i.e., D- Ascorbic acid can
be made via chemical synthesis but has
no significant biological role.

5. Structure
Vitamin C activity is possessed by two
forms:
 The L isomer i.e., L- ascorbic acid which is
the reduced form.
 The other form i.e., L-Dehydroascorbic
acid is the oxidized form which is oxidized
further and it results in complete loss of
activity.
Ascorbic acid has an enediol structure conjugated with the carbonyl group in the lactone ring. The two
enolic hydrogen atoms are the ones that give this compound its acid quality and provide the electrons for its
function as an antioxidant. In the presence of oxygen, ascorbic acid is transformed into dehydroascorbic
acid and the reaction is reversible in nature.

6. u
 Since vitamin C is a water soluble vitamin, in
aqueous solution, it dissociates to form
hydrogen ion and ascorbate ion. In biological
systems, ascorbate is present in neutral
medium (pH>5). Ascorbate and ascorbic acid
are both naturally present in the body, since
the forms interconvert according to pH.
 The reaction from ascorbic acid to its oxidized
form dehydroascorbic acid which is highly
prone to irreversible hydrolysis to 2,3-
diketogulonic acid proceeds in water which
results in the molecule losing its vitamin
activity.
 Diketogulonic acid is oxidized to smaller
molecules, including oxalate, which are
excreted in the urine.

7. Importance/ Functions
1. Collagen formation
 Collagen is a major structural protein of connective tissue (which binds cells and tissues together),
bone, teeth, cartilage, skin and scar tissue. It is formed from a precursor protein by hydroxylation
of amino acids proline and lysine within it for which Vitamin C is required. Deficiency of vitamin
C results in defective collagen synthesis, associated with impaired wound healing, disruption
of capillaries and faulty bone and tooth formation.
 Also, the matrix formation in bone is defective and is less able to accumulate calcium and
phosphorus, thus, bones becomes weak and get displaced from joint when the supporting
cartilage (mainly collagen) becomes weak.
 The dentine layer of tooth does not form normally during vitamin C deficiency; thus, teeth become
structurally weak and more prone to injury and decay.

8. 2. Carnitine synthesis: Vitamin C is required for synthesis of carnitine, which is involved in the
transport of fatty acids into mitochondria to be oxidized for energy.
3. Neurotransmitter synthesis: Vitamin C is involved in the synthesis of neurotransmitters:
 Vitamin C is required to sustain the activity of enzyme dopamine oxygenase, which catalyses
the oxidation of dopamine to form the neurotransmitter nor-epinephrine.
 It is also involved in the hydroxylation of tryptophan during the biosynthesis of serotonin.
4. Activation of hormones: Many hormones are synthesized as precursor molecules that are
enzymatically modified into their active forms for which Vitamin C is essential eg. calcitonin, gastrin,
oxytocin etc.
5. Drug detoxification: Vitamin C is required for the optimal activity of drug-detoxifying reactions in the
liver.

9. 6. Antioxidant: Many damaging oxidizing reactions normally occur in the body due to the exposure to
drugs or pollutants. Many enzymes and antioxidants like vitamin C convert these into harmless
substances than can be excreted. Vitamin C can combine with and scavenge many types of oxidizing
free radicals.
7. Vitamin C helps in regulating cholesterol metabolism by preventing oxidation of cholesterol and in
maintaining the structure of blood vessels; thus preventing cardiovascular diseases.
8. Iron metabolism: Vitamin C acts as a reducing agent, and reduces iron found in foods as ferric ions in
ferrous form and thus help in its absorption. This occurs in the duodenum where the pH is alkaline. It
also assists in the transfer of iron from blood plasma into ferritin for storage in the liver and also for the
release of iron from ferritin when required.
9. Common cold: Vitamin C supplementation significantly decreases the duration of common cold and the
severity of its symptoms. Large doses of vitamin C are prescribed during infections to increase the
immunity and capacity of healing.

10. 10. Cancers and Cardio vascular diseases: Vitamin C is a potent antioxidant and hence large doses
have been given for prevention of cancers and cardiovascular diseases.
11. Vitamin C aids calcium absorption by preventing the incorporation of calcium into insoluble
complexes.
12. It converts inactive form of folic acid into its active forms (dihydrofolic acid and tetra hydrofolic
acid) and also stabilizes the active form.
13. Vitamin C alleviates allergic reactions, enhances immune function, stimulates formation of
bile and facilitates release of some steroid hormones.
14. It can also regenerate the reduced form of vitamin E converting it back into its usual form in which
it can act as an antioxidant. It does so by readily donating electrons/hydrogen ions as the reduction
potential of ascorbate is high.
15. It is also necessary for the conversion of cholesterol to bile acids and is involved in the
detoxification of many chemical carcinogens.

11. Stability Of Vitamin C
 It is most susceptible to destruction by atmospheric
oxidation. One of its characteristic property is its intense
reducing action and hence it is oxidized rapidly in air.
Therefore, when vegetables become dry and stale or cut
and exposed to air, most of the vitamin C originally present
is destroyed.
 Heating or drying of fresh fruits or vegetables usually leads
to destruction of most of the vitamin C. Amla is an
exception among fruits not only because of its high acidity,
high vitamin C content but also because it contains
substances which partially protect the vitamin from
destruction on heating or drying.

12.  It is highly soluble in water and alcohol, and is
easily oxidised to dehydroascorbic acid in its
solubilised form. The rapid degradation of
ascorbic acid in aqueous media is still a major
factor in the formulation of its products.
 The reaction from ascorbic acid to its oxidized
form dehydroascorbic acid and the following
hydrolysis to 2,3-diketogulonic acid proceeds in
water which results in the molecule losing its
vitamin property.
 It is also reported that ascorbic acid oxidation
occurs rapidly in an alkaline environment
especially at higher temperatures (>50°C) and
its reaction with oxygen is strongly catalysed by
metal ions, particularly cupric and ferric ions.
(Degradation)

13.  Vitamin C begins to denature at temperatures as low as 86 °F, and the negative effects of heat
increase significantly at 140 °F and even more at 170 °F. In fact, pasteurisation was blamed for
the dramatic increase in infantile scurvy in the late 19th century as naturally occurring vitamin C
in milk was destroyed by pasteurisation.
 Here the effect of heat on different vegetables was observed and the percentage of vitamin C
lost at 5, 15 and 30 minutes was measured while exposed to constant heat of 140 °F (far less
extreme than most pasteurisation methods).
Percentage vitamin C lost during exposure to 140 °F heat.

14. Absorption & Transport
 Vitamin C does not require digestion prior to being absorbed into intestinal cells.
 Ascorbic acid is absorbed in the jejunum, principally by a sodium dependent active transport mechanism.
Dehydro-ascorbic acid is passively absorbed.
 As intake increases, the efficiency of absorption decreases. While vitamin C is filtered through the kidneys,
enough is reabsorbed to maintain a plasma concentration of 1.2 to 1.5 mg/ dl and a total body pool of 1.2 to
2.0 g.
 After absorption, it is transported as a free acid in plasma into the cells, including leukocytes and red blood
cells. In the tissues, Vitamin C serves as an electron donor for a number of enzymes.
 Vitamin C in excess of the amounts needed is removed with urine.
 Ascorbate and dehydroascorbate concentrations are the highest in adrenal and pituitary glands (~30-
50mg/100 g of wet tissue), intermediate in liver, spleen, heart, kidneys, lungs pancreas and leukocytes and
smaller amounts in muscles and red blood cells.

15. How to prevent Vitamin C losses?
Harvesting at the peak of maturity.
Storing in a cool, moist place.
Limiting exposure to air and sunlight.
Avoiding soaking food in water and use of cooking soda (alkali)
Cooking food in minimal amount of water or better by microwave.
Cutting the food in pieces as large as possible.
Eating fruits immediately after cutting.
Avoiding making juices.
Eating vegetable preparations immediately after cooking.
Wherever possible fresh raw vegetables should be used for obtaining enough vitamin C.

16. SOURCES

17. Sources
(Vitamin C is called the “fresh fruit and vegetable vitamin”. It is found mostly in plant foods)
Rich sources
• Amla (richest
source)
• Guava
Good Sources
• Fresh fruits and vegetables
• Green leafy vegetables (in raw form the
concentration is higher and is greater if they are
fresh, not wilted. Green leafy vegetables like
drumstick leaves and agathi are good sources of
vitamin C.)
• Citrus fruits like orange, lemon and lime
• Other fruits and vegetables like mango, papaya,
strawberry, watermelon, honey dew melon, tomato,
green peppers, cauliflower, broccoli, lettuce,
spinach etc
• Germinated whole pulses (when dry pulses and
beans are allowed to germinate, vitamin C is
formed in grain and growing sprout. 17-20 mg of
vitamin C is produced during germination per 100 g
of pulses.)
Poor sources
• Meat
• Milk
• Cereals
• Pulses
• Fats
• Sugars

19. Deficiency
Deficiency of vitamin C leads to Scurvy.
It is the most severe form of vitamin C
deficiency but is relatively rare now throughout
the world. Faulty cooking habits and
inadequate intake of fresh vegetables and
fruits are the major causes of dietary deficiency
of vitamin C.
Their early symptoms are non specific,
including fatigue, weakness, shortness of
breath, muscle cramps, aching bones, joints
and muscles and loss of appetite.
The clinical features of scurvy are
characterized by:
Bleeding gums and teeth may become loose and
eventually fall.
Gingivitis
•Small red or purple spots caused by bleeding into the
skin.
Petechiae
•Causes reddish-blue spots under the skin when total
vitamin C reserve in the body falls below 300 mg.
Haemorrhages
Sudden fall in blood pressure in certain postures.
Postural hypotension
Occurs due to reduced synthesis of connective
tissue.
Delayed wound healing
Pain in the joints.
Arthralgia

20. RDA for Indians- As per ICMR - National Institute of
Nutrition, 2020 for Vitamin-C
Men
80
(mg/day) Pregnant
Women
Lactating
Women
Children
(1-9 y)
Adolescents
(10-17 y)
Women
(NPNL)
Infants
(0-12 m)
65
(mg/day)
80
(mg/day)
115
(mg/day)
40
(mg/day)
70
(mg/day)
25
(mg/day)

21. TUL, RDA & EAR for Indians- As per ICMR - National Institute of Nutrition,
2020 for Vitamin-C
GROUP TOLERABLE UPPER LIMIT
(TUL) (mg/d)
RECOMMENDED DIETARY ALLOWANCE
(RDA) (mg/d)
ESTIMATED AVERAGE
REQUIREMENT (EAR) (mg/d)
MEN 2000 80 65
WOMEN (NPNL) 2000 65 55
PREGNANT WOMEN 2000 80 65
LACTATING WOMEN 2000 115 95
INFANTS
0-6 m
6-12 m
-
-
20
27
-
-
CHILDREN
1-3 y
4-6 y
7-9 y
350
550
800
27
32
43
22
27
36
ADOLESCENTS
Boys 10-12 y
Girls 10-12 y
Boys 13-15 y
Girls 13-15 y
Boys 16-18 y
Girls 16-18 y
1050
1300
1550
1800
1950
2000
54
52
72
66
82
68
45
44
60
55
69
57

22. Toxicity
 Toxicity is rare.
 The Tolerable Upper Limit of Vitamin C for adults is
2000 mg/day.
 The most common side effect with ingestion of large
amounts of the vitamin is gastrointestinal problems
characterized by abdominal pain, headache, fatigue,
nausea and diarrhea.
 Other side effects include increased risk of kidney
stones (since vitamin C is metabolized to oxalic acid)
and iron toxicity for those with renal disease and
disorders of iron metabolism. Hence patients with
kidney stones or renal insufficiency are currently
advised to avoid excessive intake of vitamin C.

23. References
 https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/#en8
 Indian Council of Medical Research - National Institute of Nutrition, 2020 Manual
Vitamin-C by Michael B. Davies, Royal Society of Chemistry Paperbacks.
 https://en.wikipedia.org/wiki/Chemistry_of_ascorbic_acid
 https://www.sciencedirect.com/topics/chemical-engineering/ascorbic-acid
 https://www.hsph.harvard.edu/nutritionsource/vitamin-c/
 https://www.researchgate.net/publication/321148774_Stability_and_Stabilization_of_AscorbicAcid/link/5
a6dc2e1aca2722c947e6d3e/download