The document is a detailed lecture on water-soluble vitamins, covering their biochemical functions, dietary sources, recommended daily allowance (RDA), deficiency manifestations, and specific disorders associated with each vitamin, including thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folic acid, vitamin B12, and vitamin C. Key disorders such as beri-beri, pellegra, and scurvy are highlighted, along with their clinical symptoms and impacts. The lecture emphasizes the importance of these vitamins in various metabolic processes and their role in overall health.

1. Water soluble vitamins
Lecture by
Dr.Ilakkia

3. Thiamine (Vitamin B1)
• 1st
B-complex vitamin to be identified
• Coenzyme of vit B1, (TPP) thiamine
pyrophosphate is involved in
carbohydrate metabolism.
• Thiamine & biotin(sulphur containing
vitamins) contain sulphur in their
structure

4. Thiamine (Vitamin B1)
RDA : 1-1.5 mg/day
Dietary Sources : whole grain cereals,
yeast, legumes,oilseeds,nuts (groundnuts),
pork, beef & sheep liver
Biochemical functions :
 The multienzyme complex PDH requires
TPP as coenzymes.

5. Thiamine (Vitamin B1)
Oxidative decarboxylation of α-ketoglutarate to
succinyl CoA &CO2 by α-ketoglutarate
dehydrogenase in TCA cycle requires TPP as
coenzyme.
Oxidative decarboxylation of branched chain
aminoacids (valine, leucine, isoleucine)
requires TPP.
Transketolase of HMP shunt utilises TPP as
coenzyme.

6. Thiamine (Vitamin B1)
Thiamine triphosphate & thiamine
pyrophosphate are required for acetyl choline
synthesis.
Biochemical changes in Thiamine deficiency
• In thiamine deficiency, glucose metabolism is
impaired & CNS is affected.
• Accumulation of pyruvate & lactate cause
vasodilation and increased cardiac output.
• Transketolase activity in RBCs is decreased

7. Thiamine (Vitamin B1)
Clinical manifestations
• Prolonged thiamine deficiency causes a
condition known as beri-beri
• Two types
1. Wet beriberi
2. Dry beriberi

8. Wet Beri-beri
• Characterised by cardiovascular signs & symptoms
such as edema of legs,face & trunk.
• Other CVS manifestations include palpitation,
breathelessness, rapid pulse &tachycardia.
• The underlying mechanisms involve an impaired
energy metabolism in the myocardium leading to
peripheral vasodilation, biventricular heartfailure
with pulmonary congestion and retention of sodium
& water, leading to edema.
• Death may occur due to heart failure.

10. Dry beriberi
• Nervous system is affected in this type
• It presents with progressive muscle
wasting & peripheral neuropathy.
• Lower limbs are worst affected & walking
becomes difficult.

12. Infantile Beriberi
• Seen in infants of thiamine
deficient mothers
• Infantile beri-beri occurs
suddenly and severely with
sleepnessness,restlessnes
s vomiting & convulsions.
• Death may occur due to
heart failure.

13. Wernicke - Korsakoff syndrome
• Inadequate intake & impaired intestinal absorption
of thiamine in chronic alcoholics results in certain
CNS manifestation like paralysis of extraocular
muscles & cerebellar ataxia known as wernicke’s
encephalopathy.
• When there is mental impairment with loss of
memory and apathy, it is called as korsakoff’s
psychosis.When both occur together, the condition
is referred to as Wernicke - Korsakoff‘s

14. Vitamin B2 (Riboflavin)
• Riboflavin is a yellow fluorescent
substance that is widely distributed in
plant and animal origin.
• Riboflavin in its coenzymic form takes
part in a wide variety of oxidation-
reduction reactions involved in ETC
linked to carbohydrates, lipids and
proteins metabolism.

15. Vitamin B2 (Riboflavin)
Coenzymes of Riboflavin
Riboflavin exists in 2 active coenzyme forms
1. Flavin mononucleotide (FMN)- formed by
phosphorylation of riboflavin
2. Flavin adenine dinucleotide (FAD)-
synthesised from FMN by addition of AMP
moiety.

16. Vitamin B2 (Riboflavin)
RDA : 1.5 mg/day
Dietary Sources : Milk & diary products,lean
meat, fish, eggs and legumes. Germination
enhances riboflavin content in cereals and
pulses.
Biochemical Functions
1. FMN & FAD acts as potential redox carriers.

17. Vitamin B2 (Riboflavin)
2. FMN is an integral component of complex I &
FAD is a part of complex II of ETC.
3. During the transport of reducing equivalents
(NADH) from cytosol to mitochondria FAD is
used.
4. Riboflavin plays a role in Niacin metabolism
5. FMN & FAD are required for the oxidised and
reduced form of NAD & NADP.

18. Vitamin B2 (Riboflavin)
Deficiency manifestations
• It usually affects the tongue and lips
characterised by glossitis (magenta tongue),
angular stomatitis, cheilosis (fissure like lesions
at the corners of the mouth) and genital
dermatitis.
• FAD- dependent glutathione reductase activity in
RBC is used to measure riboflavin deficiency.

19. GLOSSITIS

22. Vitamin B2 (Riboflavin)
• Riboflavin deficiency may occur in newborn
infants suffering from jaundice. Riboflavin is
light sensitive.

23. Niacin (Vitamin B3)
• Niacin can be synthesised in the body from
tryptophan (60 mg of tryptophan is used to
produce 1 mg of niacin) and it participates in
the metabolism of carbohydrates, fat and
protein. Coenzymes of Niacin
1. Nicotinamide adenine dinucleotide (NAD+)
2. Nicotinamide adenine dinucleotide
phosphate (NADP+)

24. Niacin (Vitamin B3)
RDA : 20 mg/day
Dietary sources : Liver, meat, beans,
legumes,egg, whole grains & dried yeast
Biochemical Functions
1. NAD+ & NADP+ acts as hydrogen
acceptors and donors in metabolic
pathways.

25. Niacin (Vitamin B3)
Deficiency Manifestations
Pellagra is a disease caused by the deficiency
of niacin. It is characterised by 3 D’s-
Dermatitis (erythema resembling sunburns),
Diarrhea (loose stools with blood & mucus)
and Dementia (mental changes including
depression and loss of memory)

26. Pantothenic acid (vitamin B5)
• In greek pantos- everywhere
• Pantothenic acid participates in carbohydrate,
protein & lipid metabolism as coenzyme A
(coenzyme form of pantothenic acid)
RDA : 10 mg/day
Sources : (Plant & animal sources – egg
yolk,liver, yeast,legumes,wholegrains &
vegetables)

27. Pantothenic acid (vitamin B5)
Biochemical functions
1. More than 70 enzymes in various metabolism
are dependent on CoA.
2. As a component of acetyl CoA, coenzyme A is
considered to be central to the integration of
metabolism.
3. Acyl CoA, Acetyl CoA, propionyl CoA, succinyl
CoA & HMG CoA are derivatives of coenzyme
A.

28. Pyridoxine (Vitamin B6)
• Vitamin B6 refers to a family of closely related
compounds- pyridoxine, pyridoxal, pyridoxamine.
• The active form of Vitamin B6 is Pyridoxal
phosphate (PLP).
• PLP acts as coenzyme for more than 100
enzymes in metabolic reactions.

29. Pyridoxine (Vitamin B6)
RDA : 2 mg/day
Sources : wheat bran, rice bran, dried yeast, legumes,
nuts, milk, fish, eggs & leafy vegetables
Biochemical functions
1. Transamination reactions require PLP as
coenzyme
2. PLP is required as a coenzyme by many
decarboxylase enzymes for decarboxylation.
(Histidine, catecholamines, GABA)

30. Pyridoxine (Vitamin B6)
3. Production of niacin coenzymes require
PLP.
4. The regulatory enzyme of heme
synthesis, ALA synthase is dependent
on PLP and hence B6 deficiency
causes anemia.
5. The phosphorylase enzyme of
glycogenolysis requires PLP

31. Pyridoxine (Vitamin B6)
6. PLP is involved in the synthesis of
sphingolipids and formation of myelin.
7. Transsulphuration (transfer of sulphur from
methionine to serine to form cysteine) is PLP
dependent.
8. Serine is synthesised from glycine by PLP-
dependent hydroxy methyl transferase.

32. Pyridoxine (Vitamin B6)
Deficiency Manifestations
• Vitamin B6 deficiency is rare as it is available in
most of the foods
• When deficiency occurs, the symptoms are
Neurological, Hematological and
Dermatological
• Carpel Tunnel syndrome characterised by
synovial swelling and tenderness may occur
due to Vit B6 deficiency

33. Biotin (Vitamin B7)
• Biotin is a sulphur containing enzyme participates
in carboxylation reactions.
• It plays an important role in gluconeogenesis &
fatty acid synthesis.
• Biotin is popularly known as anti-egg-white injury
factor.
RDA : 200-300 mg/day
Sources : It is widely distributed in foods of plant &
animal origin.

34. Biotin (Vitamin B7)
• Biotin in food sources occurs in a protein bound form,
an enzyme biotinidase dissociates the vitamin from
the protein and helps in absorption and transport.
Deficiency Manifestations
• Biotin deficiency is uncommon since it is synthesised
by intestinal microflora
• Prolonged use of antibiotics kills the gut bacteria and
consumption of raw eggs result in biotin deficiency.
(symptoms- dermatitis, depression, glossitis &
nausea)

35. Biotin (Vitamin B7)
Biochemical Functions
1. Conversion of pyruvate to oxaloacetate an
important reaction in gluconeogenesis is
catalysed by biotin dependent pyruvate
carboxylase.
2. Biotin is required for the initial reaction of fatty
acid biosynthesis
3. Propionyl CoA & branched chain aminoacids
requires biotin for its further metabolism.

36. Folic acid (Vitamin B9)
• The word folate comes from the latin word
folia (meaning leaf)
Coenzyme of Folic Acid
Tetrahydrofolate is the coenzyme form of folic
acid .
Folic acid is reduced to THF by the enzyme
folate reductase.

37. Folic acid (Vitamin B9)
RDA : 200 µg/day, 400 µg/day during pregnancy &
300 µg/day during lactation
Sources : Green leafy vegetables, cereals,fruits,
eggs & diary products.
Bananas,oranges,cauliflower and broccoli
contain high levels of folate.
Biochemical functions
THF serves as a donor or acceptor of one
carbon units (formyl,methyl).

38. Folic acid (Vitamin B9)
• THF is involved in the conversion of serine to
glycine, the catabolism of Histidine and the
synthesis of methionine.
• THF is required for the formation of N-
formylmethionine, which initiates protein
biosynthesis
• The one carbon groups are utilised for the
synthesis of C2 & C3 of purine ring.

39. Folic acid (Vitamin B9)
Deficiency Manifestations
 Pregnant women are more susceptible to folate
deficiency due to their increased requirements.
Macrocytic anemia with megaloblastic changes
in the bone marrow is the characteristic feature
of folate deficiency
Folate deficiency during the first trimester of
pregnancy may lead to neural tube defects in
the fetus.(spina bifida, anencephaly)

40. Folic acid (Vitamin B9)
Folate deficiency may block the conversion of
homocysteine to methionine, causing the
accumulation of homocysteine.
Hyperhomocysteinemia is known to increase the
risk of coronary heart disease.
Folate deficiency may be associated with different
types of malignancy, especially cervical cancer &
colon cancer.(FIGLU – formimino glutamate is
accumulated & excreted in folate deficiency)

42. Vitamin B12
• Vitamin B12 is also known as cobalamin,
is required for the maturation of RBC.
• Vitamin B12 is a complex organometallic
compound with a centrally placed cobalt
atom.
• Methylcobalamin & deoxyadenosyl
cobalamine acts as the coenzymes of Vit
B12.

44. Vitamin B12
RDA : 1µg/day, during pregnancy and
lactation 3µg/day
Sources : It occurs in foods of animal origin. It is not
found in foods of plant origin. Liver, meat,
fish,eggs,milk, curd & cheese.

45. Vitamin B12
Biochemical Functions
Vitamin B12 is a component of enzymes found in
bacteria.
There are only two reactions identified in humans
1. Synthesis of methionine
2. Conversion of methylmalonyl CoA to succinyl
CoA.

46. Vitamin B12
Deficiency Manifestations
1. Megaloblastic anemia
2. Subacute combined degeneration
3. Pernicious anemia
4. Coronary artery disease.

47. Vitamin C
• Also known as ascorbic acid
• Vitamin c is involved in the formation of
collagen.
• Plants & most animals synthesise Vit C
through uronic acid pathway.
• Humans, monkeys, guinea pigs and bats
cannot synthesise ascorbic acid because they
lack an enzyme L- gulanolactone oxidase

48. Vitamin C
RDA : 60-75 mg/day, 100 mg/day during pregnancy
and lactation.
Sources : Fresh fruits & green leafy vegetables ,
citrus fruits & germinating pulses contain large
amount of vit C
Biochemical functions
1. Collagen formation

49. Vitamin C
2. Wound healing – post operative cases vit c is
prescribed for surgical wound healing
3. Antioxidant
4. Role in Aminoacid metabolism
5. Role in lipid metabolism
6. Role in iron metabolism
7.Role in hemoglobin metabolism

50. Vitamin C
8. Phagocytosis
9. Synthesis of hormones
10. Drug metabolism
11. Cell respiration
Deficiency Manifestations
• Vitamin C deficiency causes scurvy
• Poor wound healing & anemia

51. Vitamin C
• Swollen and painful gums
• Scurvy in infants is known as Barlows disease