The Water Soluble Vitamins: B and C

The Water Soluble Vitamins: B
and C
Chapter 10
Nalini Narahari

1


Overview of Vitamins
Vitamins are organic substances required in
minute quantities (micrograms to milligrams)
 Vita means life; amine: nitrogen containing






The first vitamins discovered has nitrogen

Specific functions include:





Nurture growth; reproduction; maintain life
Prevent deficiency diseases
Do not provide energy;
Help the enzymes that release energy from the
carbs, fats and proteins

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Cont.
•

Structure:
•

•

Food contents:
•
•

•

Individual units; not connected like molecules of
glucose, fatty acids and amino acids
Vitamins present in foods are ingested
Required in small quantities; measured in micro
grams and milligrams

Know the terms:
•

Bioavailability; precursors; coenzymes
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Thiamin
 Water

soluble vitamin
 Part of the coenzyme, Thiamin Pyro
Phosphate (TPP)
 Assists

in energy metabolism

 Recommendations:
 Men

1.2 mg/d;

 Prolonged
 The

1998 RDA

women 1.1 mg/d

deficiency leads to beriberi

custom of polishing rice in Asia
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Cont.



Severe thiamin deficiency in alcohol abusers:
Wernicke- Korsakoff syndrome







Disorientation
Loss of short term memory
Jerky eye movements
Staggering gait

Food sources:



Whole grain, fortified and enriched products
Pork; ham

5


Riboflavin
 Acts

as coenzyme in many metabolic

reactions
 Flavin

Mono Nucleotide (FMN)
 Stable when heated
 Breaks down in light and radiation


Milk sold in opaque/translucent containers

 Recommendations:
 Men

1.3 mg/d

1998 RDA

women 1.1 mg/d

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Cont.
 Deficiency: Ariboflavinosis
 Inflammation

GI tract

 Food

of the mouth, skin ,eyes, and

sources:

 Milk

and milk products
 Enriched products
 Liver
 Canned clams
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Niacin


Occurs as nicotinic acid and nicotinamide




Body transforms nicotinic acid to nicotinamide, a
major form of niacin in the blood
Body can make niacin from its precursor,
tryptophane

Stable in heat
 Recommendations: 1998 RDA





Men 16 mg/d Women 14 mg/d
Niacin:lipid lowering function (niacin flush)
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Cont.
 Severe

deficiency leads to pellagra

 Dermatitis
 Diarrhea
 Dementia

 Food

sources:

 Milk;

eggs, meat, poultry, fish,
 Whole grains and enriched products
 All protein containing foods
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Biotin

 As

a coenzyme plays a major role in
metabolism
 Delivers a carbon to 3-carbon pyruvate:
formation of oxaloacetate to continue
with the TCA cycle
 Stable to heat
 1998 Adequate intake (AI)
 Adults

30 micrograms/d
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Cont.


Deficiency is rare



Can be induced by ingesting large quantities of egg
whites that contain avidin
Avidin is a protein in egg whites that bind biotin and
makes it unavailable to the body






About 2-dozen raw eggs!

Symptoms include skin rash, hair loss, and
neurological impairments

Food sources:


Organ meats, egg yolks, soybeans, fish, whole
grains

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Pantothenic Acid
Part of many reactions in the synthesis of lipids,
neurotransmitters, steroid harmone and
hemoglobin
 Unstable in heat




Destroyed by food processing

1998 AI: adults 5 mg/d
 Deficiency is rare; “the burning feet”
 Food sources:





Organ meats, mushroom, avocado, broccoli and
whole grains

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Vitamin B6


Occurs in three forms




These forms can be converted to the coenzyme,
pyridoxal phosphate (PLP)
PLP can transfer amino acids, and thus body can
make nonessential amino acids
Alcohol interacts with Vitamin B6




Destroys and makes it unavailable to the body

The drug INH prescribed to treat tuberculosis acts

as an antagonist to the vitamin



B6 supplements are given to patients
B6 & carpal tunnel syndrome/oral contraceptives

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Cont.


Recommendations:




Deficiency rarely occurs




Symptoms include depression, confusion

Toxicity first reported in 1983





Adults (19-50 years) 1.3 mg/d

Women taking more than 2 mg of B6/day (PMS)
Correlation between B6 and carpal tunnel syndrome
not conclusive

Food sources:


Meat, fish, poultry,legumes, non citrus fruits, liver

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Folate (Folic Acid)
Involved in protein metabolism
 Critical role in the synthesis of DNA







Involved in new cell development
Requires the help of the vitamin B12

Folate is secreted into the GI tract with bile


If the cells of the GI tract are injured/destroyed as
in the case of alcohol abuse, then folate can not
be absorbed, and leads to deficiency

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Cont.
 Unstable;

destroyed by heat and oxygen

 Caution

with food processing, preparation
and storage

 Recommendations:

1998 RDA

 Adults

400 micrograms
 The difference in bioavailability of folate
from food versus supplements considered
before setting the RDA for folate

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Cont.


Deficiency leads to macrocytic or
megaloblastic anemia, and GI tract
deterioration






Diarrhea, fatigue, depression and confusion
Impairs cell division and protein synthesis
Alters DNA metabolism
Reported in babies fed on goat’s milk
Folate perhaps most affected by drug interaction
which has similar chemical structure


Can lead to secondary deficiency

17


Cont.
Cancer cells need folate to multiply;
 Anti cancer drugs can create deficiency of folate

to other normal cells


 Antacids

and aspirins interfere with folate
 Smoking and oral contraceptives affect
folate status
 Pregnant women are prone to folate
deficiency


Studies have documented the need for folate to
reduce the risks of neural tube defects

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Cont.




FDA has mandated that grains should be fortified with
folate ( on the food label)

Folate and heart disease:


Research studies have identified the role of folate

in defending against heart disease

Folate deficiency may mask the vitamin B12
deficiency
 Food Sources:




Fortified grains, green leafy vegetables(foliage),
legumes, seeds, and liver

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Vitamin B12 Cobalamin
 Close

relationship between vitamin B12
and folate
 Depend

on each other for activation

 Microwave

cooking destroys B12
 Intrinsic factor:
 The

HCL and pepsin in the stomach
release B12 from the protein foods to which
it is attached
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Cont.
 The

next step the intrinsic factor attaches
to B12
 Then the whole complex passes to the
small intestine where the gradual
absorption of B12 occurs
 Reabsorption of B12 happens continuously
 Recommendations:

1998 RDA
 Adults 2.4micrograms
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Cont.


Deficiency caused by inadequate absorption
rather than poor intake


Lack of HCL or lack of intrinsic factor





Without HCL, the vitamin cannot be released from
protein, and cannot attach to intrinsic factor

Atrophic gastritis:


Commonly in older people, the stomach cells get
damaged



Could be due to iron deficiency or Helicobacter pylori
No healthy cells; No action of HCL and intrinsic factor

22


Cont.




Result is pernicious anemia due to a combination
of atrophic gastritis and lack of intrinsic factor
Other factors are defective gene for intrinsic factor,
or if the stomach is injured or damaged




In that case B12 must be injected
Nasal spray of B12; absorption is rapid

High dose of folate masks B12 deficiency






In both deficiency states, the first symptom is that
the blood cells grow rapidly
Either of the vitamins-supplement will be effective

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Cont.


However if folate is administered when B12 is
needed, the situation will be disastrous







Results in devastating neurological symptoms
B12 deficiency leads to nerve damage caused by
destruction of myelin sheaths that protect the nerves
Note: folate can clear the blood symptoms but cannot
stop the nerve damage

Food sources:


Animal sources: meat, fish, poultry, eggs, shellfish,
milk/products, fortified cereals; soy milk with B 12

24


Non- B Vitamins
 Choline:
 Body

can synthesize; needed for the
synthesis of acetyl choline, a
neurotransmitter, and Phospholipid lecithin
 Deficiency may cause liver damage
 1998 AI men 550 mg/d; women 425 mg/d
 Food sources;


Milk, liver,eggs and peanuts

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