This document discusses vitamin C and several B vitamins. It provides information on their functions, dietary sources, deficiency symptoms, recommended intake levels, and other details. Vitamin C plays roles in collagen formation, bone formation, antioxidant activity, and immune function. The B vitamins discussed include thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folic acid (B9), and their involvement in metabolism and cell function through their coenzyme forms. Deficiency of several B vitamins can cause conditions like beriberi, pellagra, and megaloblastic

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WaterSolubleVitamins
Vitamin C (Ascorbic Acid)
Vitamin C is a water soluble versatile vitamin. It plays an important role in human
health and disease. Vitamin C has become the most controversial vitamin in recent
years. This is because of the claims and counter-claims on the use of vitamin C in
mega doses to cure everything from common cold to cancer.
Functions of Vitamin C
1. Collagenformation: Vitamin C plays the role of a coenzyme to convert
protocollagen to collagen (i.e. post-translational modification).
2. Bone formation: Bone tissues possess anorganic matrix, collagen and the
inorganic calcium, phosphateetc. Vitamin C is required for bone formation.
3. Sparing actionof other vitamins: Vitamin C is a strong antioxidant. It
spares vitamin A, vitamin E, and some B-complex vitamins from oxidation.
4. Immunological function: Vitamin C enhances the synthesis of
immunoglobulins (antibodies) and increases the phagocytic action of
leucocytes.
5. Preventive actionon cataract:Vitamin C reduces the risk of cataract
formation.
6. Preventive actionon chronic diseases:As an antioxidant, Vitamin C
reduces the risk of cancer and coronary heart diseases.
Dietary sources
Citrus fruits, gooseberry (amla), guava, green vegetables (cabbage, spinach),
tomatoes, potatoes (particularly skin) are rich in vitamin C. Milk is a poorsource
of vitamin C.
Vitamin C Deficiency
The deficiency of Vitamin C results in scurvy. This disease is characterized by
spongy and sore gums, loose teeth, swollen joints, fragile blood vessels, decreased
immunocompetence, osteoporosis etc. Most of these symptoms are related to
impairment in the synthesis of collagen and/or the antioxidant property of vitamin
C.

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Mega doses of Vitamin C
Mega doses of vitamin C are still continued in common cold because it reduces the
duration of cold and the severity of symptoms but it does not prevent common
cold. As an antioxidant, vitamin C certainly provides some health benefits.
Vitamin C, as such, has not been found to be toxic. But oxidized form of Vitamin
C is toxic. Further, oxalate, a major metabolite of vitamin C, has been implicated
in the formation of kidney stones. However, there are controversial reports on the
mega doses of vitamin C leading to urinary stones.
Recommended dietary allowance (RDA)
About 60-70 mg vitamin C intake per day will meet the adult requirement.
Additional intakes (20-40% increase) are recommended for women during
pregnancy and lactation.
Vitamin B1 (Thiamine)
Vitamin B1 is water soluble vitamin.
Functions of Vitamin B1
1. Vitamin B1 has a specific coenzyme, thiaminepyrophosphate (TPP) which
is mostly associated with carbohydrate metabolism.
2. TPP plays an important role in the transmission of nerve impulse. It is
believed that TPP is required for acetylcholine synthesis and the ion
translocation of neural tissue.
3. Vitamin B1 plays a significant role in the functioning of the nervous system.
Dietary sources
Cereals, pulses, oil seeds, nuts and yeast are good sources ofvitamin B1. Vitamin
B1 is mostly concentrated in the outer layer of cereals. Polishing of rice removes
about 80% of Vitamin B1. Vitamin B1 is also present in animal foods like liver,
heart, kidney, milk etc.

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Vitamin B1 Deficiency
The deficiency of vitamin B1 results in a condition called beri-beri which affects
the legs. Beri-beri is mostly seen in populations consuming exclusively polished
rice. The early symptoms of vitamin B1 deficiency are loss of appetite (anorexia),
weakness, constipation, nausea, mental depression. Numbness in the legs,
complaints of pins and needles sensations are reported.
Thiamine antagonists
Pyrithiamineand Oxythiamineare the two important antagonists of thiamine.
Recommended dietary allowance (RDA)
The daily requirement of Vitamin B1 depends on the intake of carbohydrate. A
dietary supply of 1-1.5 mg per day is recommended for adults. For children RDA
is 0.7-1.2 mg per day. The requirement marginally increases in pregnancy and
lactation (2 mg per day), old age and alcoholism.
Vitamin B2 (Riboflavin)
Vitamin B2 is a water soluble vitamin.
Functions of Vitamin B2
1. Vitamin B2 through its coenzymes takes part in a variety of cellular
oxidation-reduction reactions and thus is necessary for proper functioning of
cells.
2. Vitamin B2 plays an important role in energy metabolism.
3. It is required for metabolism of carbohydrates, proteins, lipids and purines.
Dietary sources
Milk and milk products, meat, eggs, liver, kidney are rich sources. Cereals, fruits,
vegetables and fish are moderate sources.

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Vitamin B2 Deficiency
Vitamin B2 deficiency affects the digestive system. The personmay experience
dizziness frequently, hair loss, skin rashes and eye problems. Vitamin B2
deficiency symptoms include glossitis (tongue smooth and purplish) and
dermatitis.
Antimetabolites of Vitamin B2
Galactoflavin is an antimetabolite of Vitamin B2.
Recommended dietary allowance (RDA)
The daily requirement of Vitamin B2 for adult is 1.2-1.7 mg. The requirement of
vitamin B2 for pregnant and lactating women is 0.2-0.5 mg per day.
Vitamin B3 (Niacin or nicotinic acid)
Vitamin B3 is a water soluble vitamin. It is also known as pellagra preventive
(P.P.)factor of Goldberg. The coenzymes of niacin (NAD+ and NADP+) can be
synthesized by the essential amino acid, tryptophan.
The disease pellagra (Italian: rough skin) has been known for centuries. However,
its relation to the deficiency of a dietary factor was first identified by Goldberg.
Functions of Vitamin B3
1. The coenzymes (NAD+ and NADP+) of vitamin B3 are involved in a
variety of oxidation-reduction reactions.
2. The coenzymes (NAD+ and NADP+) of vitamin B3 participate in the
metabolisms of carbohydrates, lipids, proteins, etc.
Therapeutic uses of Niacin or Vitamin B3
1. Niacin inhibits lipolysis in the adipose tissue and decreases the circulatory
free fatty acids.
2. It decrease the synthesis of triacylglycerol in the liver.
Dietary sources
The rich natural sources of Vitamin B3 include liver, yeast, whole grains, cereals,
pulses like beans and peanuts. Milk, fish, eggs & vegetables are moderate sources.

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Vitamin B3 Deficiency
Vitamin B3 deficiency results in a condition called pellagra(Italian:rough skin).
This disease involves skin, gastrointestinal tract and central nervous system. The
symptoms of pellagra are commonly referred to as three Ds. The disease also
progresses in that order dermatitis, diarrhea, dementia, and if not treated may
rarely lead to death (4th D).
Dermatitis (inflammation of skin) is usually found in the areas of the skin exposed
to sunlight (neck, dorsalpart of feet, ankle and parts of face).
Diarrhea may be in the form of loose stools, often with blood and mucus.
Prolonged diarrhea leads to weight loss.
Dementia is associated with degeneration of nervous tissue. The symptoms of
dementia include anxiety, irritability, poormemory, insomnia (sleeplessness) etc.
Mega Doses of Vitamin B3
Although mega doses of vitamin B3 are useful for the treatment of hyperlipidemia,
there are certain harmful side effects also which are:
1. Glycogen and fat reserves of skeletal and cardiac muscles are depleted.
2. Prolonged use of niacin results in elevated serum levels of certain enzymes,
suggesting liver damage.
Recommended dietary allowance
The daily requirement of vitamin B3 for an adult is 15-20 mg and for children,
around 10-15 mg.
Vitamin B5 (Pantothenic Acid)
Vitamin B5 (Pantothenic Acid) is a water soluble vitamin. Pantothenic acid
(Greek: pantos-everywhere), formerly known as chick anti-dermatitis factor is
widely distributed in nature. Its metabolic role as coenzyme A is also widespread.
Functions of Vitamin B5
1. The functions of vitamin B5 are exerted through coenzyme A. Coenzyme A
is a central molecule involved in metabolisms of carbohydrates, lipids and
proteins.

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2. Besides the various functions of through coenzyme A, pantothenicacid
itself is a componentof fatty acid synthase complex and is involved in the
formation of fatty acids.
Dietary sources
Vitamin B5 is one of the most widely distributed vitamins found in plants and
animals. The rich sources are egg, liver, meat, yeast, milk etc.
Vitamin B5 Deficiency
It is a surprise to biochemists that despite the involvement of pantothenic acid (as
coenzyme A) in a great number of metabolic reactions, its deficiency
manifestations have not been reported in humans. This may be due to the
widespread distribution of this vitamin or the symptoms of vitamin B5 may be
similar to other vitamins deficiencies. Dr. Gopalan, a world renowned nutritionist
from India, linked the Burningfeet syndrome (pain and numbness in the toes,
sleeplessness, fatigue etc.) with vitamin B5 deficiency.
Vitamin B5 deficiency in experimental animals results in anemia, fatty liver,
decreased steroid synthesis etc.
Recommended dietary allowance (RDA)
The requirement of vitamin B5 for humans is not clearly known. A daily intake of
about 5-10 mg is advised for adults.
Vitamin B6 (Pyridoxine)
Vitamin B6 is a water soluble vitamin. Vitamin B6 is used to collectively represent
the three compounds namely pyridoxine, pyridoxaland pyridoxamine (the
vitamers of vitamin B6).
Synthesis of coenzyme
The active form of vitamin B6 is the coenzyme pyridoxal phosphate(PLP). PLP
can be synthesized form the three compounds pyridoxine, pyridoxal and
pyridoxamine.

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Functions of Vitamin B6
1. Pyridoxal phosphate (PLP), the coenzyme of vitamin B6 is closely
associated with the metabolism of amino acids.
2. Pyridoxal phosphate participates in reactions like transamination,
decarboxylation, deamination, condensation etc.
3. PLP is needed for the absorption of amino acids from the intestine.
4. Adequate intake of vitamin B6 is useful to prevent hyperoxaluria and urinary
stone formation.
5. PLP is also involved in the synthesis of certain specialized products suchas
serotonin and histamine form amino acids.
Dietary sources
Animal sources suchas egg yolk, fish, milk, meat are rich in vitamin B6. Wheat,
corn, cabbage, and roots are good vegetable sources of vitamin B6.
Vitamin B6 Deficiency
Vitamin B6 deficiency is associated with neurological symptoms suchas
depression, irritability, nervousness and mental confusion. Epilepsy is observed in
severe deficiency.
Dietary deficiency of vitamin B6 is rather rare and is mostly observed in women
taking oral contraceptives, alcoholics and infants.
Toxic effects of overdose vitamin B6
Excess use of vitamin B6 (2.5 g per day) in the women of premenstrual syndrome
is associated with sensory neuropathy. Some workers have suggested that vitamin
B6 more than 200 mg per day may cause neurological damage.
Pyridoxine antagonists
Isoniazid, deoxypyridoxine and methoxypyridoxine are the antagonists of vitamin
B6.
Recommended dietary allowance (RDA)
The requirement of vitamin B6 for an adult is 2-2.2 mg per day. During pregnancy,
lactation and old age, an intake of 2.5 mg per day is recommended.

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Vitamin B7 (Biotin)
Biotin (formerly known as anti-egg white injury factor, vitamin B7 or vitamin H)
is a sulfur containing B-complex water soluble vitamin. It directly participates as a
coenzyme in the carboxylation reactions.
Boas (1927) observed that rats fed huge quantity of raw egg white developed
dermatitis and nervous manifestations, besides retardation in growth. She however,
found that feeding cooked egg did not produceany of these symptoms. It was later
shown that the egg white injury in rats and chicks was due to the presence of an
anti-vitamin in egg white. The egg-whiteinjuryfactor was identified as a
glycoprotein-avidin and biotin was called as anti-egg whiteinjuryfactor.
Functions of Vitamin B7
1. In biologic system, biotin functions as the coenzyme for the enzyme called
carboxylases, which catalyze the CO2 fixation (Carboxylation).
2. Vitamin B7 is also involved in gluconeogenesis for the synthesis of glucose
from non-carbohydrate sources.
3. It is involved in the synthesis of fatty acids.
4. It is also involved in the metabolisms of certain amino acids such as valine,
leucine, isoleucine etc.
Dietary sources
Vitamin B7 is widely distributed in both animal and plant foods. Therich sources
are liver, kidney, egg yolk, milk, tomatoes, grains etc.
Vitamin B7 Deficiency
The symptoms of vitamin B7 deficiency include anemia, loss of appetite, nausea,
dermatitis etc. Vitamin B7 deficiency may also results in depression, hallucinations
and muscle pain.
Vitamin B7 deficiency is uncommon, since it is well distributed in foods and also
supplied by the intestinal bacteria. The deficiency may however, be associated with
the following two causes.
1. Destruction of intestinal flora due to prolonged use of drugs such as
sulfonamides.
2. High consumption of raw eggs. The raw egg white contains a glycoprotein-
avidin,which tightly binds with vitamin B7 and blocks its absorption from

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the intestine. An intake of about 20 raw eggs per day is needed to produce
vitamin B7 deficiency symptoms in humans. Consumption of an occasional
raw egg will not result in deficiency.
Antagonists of Vitamin B7
Desthibiotin, biotin sulphonic acid are vitamin B7 antagonists.
Recommended dietary allowance (RDA)
A daily intake of about 100-300mg is recommended for adults. In fact, vitamin B7
is normally synthesized by the intestinal bacteria. However, to what extent the
synthesized vitamin B7 contributes to the bodyrequirements is not clearly known.
Vitamin B9 (Folic Acid)
Vitamin B9 or Folic acid (Latin: folium-leaf) is abundantly found in green leafy
vegetables. It is a water soluble vitamin.
Functions of Vitamin B9
1. Tetrahydrofolate (THF or FH4 ), the coenzyme of folic acid or vitamin B9, is
actively involved in the one carbon metabolism. THF serves as an acceptor
or donorof one carbon units (formyl, methyl etc.) in a variety of reactions
involving amino acid and nucleotide metabolism.
2. It helps in the productionof DNA and RNA.
3. It also helps in the productionof red blood cells (RBCs).
Dietary sources
Vitamin B9 is widely distributed in nature. The rich sources are green leafy
vegetables, whole grains, cereals, liver, kidney, yeast and eggs. Milk is rather a
poorsourceof vitamin B9.
Vitamin B9 Deficiency
Vitamin B9 deficiency is probably the most common vitamin deficiency, observed
primarily in the pregnant women, in both developed countries (including USA) and
developing countries (including Pakistan). The pregnant women, lactating women,
women on oral contraceptives, and alcoholics are also susceptible to vitamin B9

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deficiency. Vitamin B9 deficiency may be due to (one or more causes) inadequate
dietary intakeand defective absorption.
In vitamin B9 deficiency, decreased productionof purines is observed which
impairs DNA synthesis. Due to block in DNA synthesis, the maturation of
erythrocytes is slowed down leading to macrocytic RBC. The rapidly dividing cells
of bone marrow are seriously affected. The macrocyticanemia(abnormally large
RBC) associated with megaloblastic changes in bone marrow is a characteristic
feature of vitamin B9 deficiency.
Vitamin B9 deficiency in pregnant women may cause neural defects in fetus.
Hence high doses of vitamin B9 are recommended in pregnancy to prevent birth
defects.
Vitamin B9 Antagonists
Aminopterin and amethopterin (also called methotrexate) are structural analogues
of vitamin B9. They competitively inhibitdihydrofolatereductase and block the
formation of Tetrahydrofolate (THF). The biosynthesis of purines, thymine
nucleotides and hence DNA is impaired. This results in the blockage of cell
proliferation. Aminopterinand methotrexateare successfully used in the
treatmentof manycancers, includingleukemia.
Recommended dietary allowance (RDA)
The daily requirement of vitamin B9 is around 200 microgram. In the women,
higher intakes are recommended during pregnancy (400 micro gram per day) and
lactation (300 micro gram per day).
Vitamin B12 (Cobalamin)
Vitamin B12 is also known as anti-perniciousanemiavitamin. Itis a water
soluble vitamin. It is a unique vitamin, synthesized by only microorganisms and
not by animals and plants. It was the last vitamin to be discovered.
Vitamin B12 has two coenzymes, deoxyadenosylcobalamin and methlycobalamin.

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Functions of Vitamin B12
1. Vitamin B12, as methylcobalamin is used in the synthesis of methionine
from homocysteine in the presence of an enzyme called methionine
synthase.
2. Vitamin B12 is necessary for the productionof red blood cells (RBCs).
3. It works with Vitamin B9 in making body’s genetic material.
Dietary sources
Foods ofanimal origin are the only sources for vitamin B12. The rich sources are
liver, kidney, milk, curd, eggs, fish and chicken. Curd is a better source than milk
due to the synthesis of vitamin B12 by Lactobacillus.
Vitamin B12 is synthesized only by microorganisms (anaerobic bacteria). Plants
cannot synthesize, hence vitamin B12 is never found in plant foods. Animals
obtain vitamin B12 either by eating foods, derived from other animals or from the
intestinal bacterial synthesis.
Vitamin B12 Deficiency
The most important disease associated with vitamin B12 deficiency is pernicious
anemia. Itis characterized by low hemoglobin levels, decreased number of
erythrocytes and neurological manifestations. One or more of the following causes
are attributed to the occurrence of pernicious anemia.
1. Autoimmune destruction of gastric parietal cells that secrete intrinsic factor
(IF). In the absence of IF, vitamin B12 cannot be absorbed.
2. Hereditary malabsorption of vitamin B12.
3. Partial or total gastrectomy- these individuals become intrinsic factor
deficient.
4. Insufficient productionof IF and/or gastric HCl, occasionally seen in older
people.
5. Dietary deficiency of vitamin B12 is seen among the strict vegetarians of
low socioeconomic group in the developing countries (India, Sri Lanka etc.).
From the above discussion, it is clear that pernicious anemia is more a disease of
the stomach than duo the deficiency of vitamin B12.
Vitamin B12 deficiency is also associated with neuronal degeneration and
demyelination of nervous system. The symptoms include paresthesia (numbness

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and tingling) of fingers and toes. In advanced stages, confusion, loss of memory
and even psychosis may be observed.
Treatment
Vitamin B12 is administered in therapeutic doses (100-1000 micro gram)
intramuscularly. Vitamin B9 administration can also reverse hematological
abnormalities observed in vitamin B12 deficiency. However, the neurological
symptoms persist. Therefore, a combined supplementation of vitamin B12 and
vitamin B9 is employed to treat the patients with megaloblastic anemia.
Recommended dietary allowance (RDA)
A daily intake of about 3 microgram of vitamin B12 is adequate to meet the adult
requirements. Forchildren, 0.5-1.5 microgram per day is recommended. During
pregnancy and lactation, the requirement is 4 micro gram perday.
Writtenby: Ashfaq Ahmad
BS Biotechnology
3rd
Semester
Abdul Wali Khan UniversityMardan

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