Fat Soluble Vitamins
Water Soluble Vitamins
Characteristics of Vitamins
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Vitamins are micronutrients
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Vitamins are essential.
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The roles they play in the body are very important.
Most vitamins are obtained from the foods we eat.
Some are made by bacteria in the intestine
There is no perfect food that contains all the vitamins in
the right amount.
Vitamins are non-energy producing
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Very small amounts are needed by the body (>1 gm)
Very small amounts are contained in foods.
They do not contain kcalories.
Vitamins are classified according to how soluble they
are in fat or water.
Fat Soluble Vitamins vs.
Water Soluble Vitamins
A, D, E, K
Fat-Soluble Vitamins
 found in fats and oils
 require bile for absorption
 enter the lymph, then the blood
 held and stored in fatty tissues
 Needed in small amounts
 may reach toxic levels
 not readily excreted
Vitamin A
 3 forms in the body
 Retinol
 retinal
 retinoic acid
 collectively known as retinoids
precursor: beta-carotene
derived from plant foods
can split and form retinol in intestine and
liver
Beta-carotene
Dark leafy green vegetables
Deep orange veggies
Deep orange fruits
Vitamin A function
 vision
maintain epithelial tissue and skin
support reproduction and growth
 Immune system
 Bone development
Vitamin A
 deficiency
 infectious disease

pneumonia, measles, diarrhea
 keratinization

dry, rough, scaly skin
 night blindness
Vitamin D
 body can make
 from sunlight
 precursor made from
cholesterol
 production occurs in liver and kidney
 diseases can affect activation
sources
 fortified food: milk, margarine, cereals, beef, eggs
 sun
 storage from the summer does not last the winter
Vitamin D function
 part of the bone-making/maintenance team
 maintains blood concentrations of Ca & P
Mineralization of bones
 raises
blood calcium and phosphorus by increasing
absorption from digestive tract
 withdrawing calcium from bones
 stimulating retention by kidneys
 deficiencies
 ultimately creates a calcium deficiency
 rickets, osteomalacia or rickets
Vitamin E
 antioxidant
 defender against free radicals

polyunsaturated fatty acids
 may reduce the risk of heart disease
 widespread in food
 easily destroyed by heat processing
 deficiencies
 rare
 erythrocyte hemolysis
An antioxidant is a molecule that inhibits the
oxidation of other molecules.
Vitamin K
 aids in blood clotting and
bone mineralization
 deficiency causes hemorrhagic disease
 sources
 made by bacteria in GI tract

absorbed and stored in liver
B complex , c
Water soluble vitamins
 The B-complex vitamins are often associated with giving a
person more energy. This is due to the fact that these
vitamins each play different roles with energy metabolism
in the body. When they are present in the body, they allow
energy to be used more readily by the body.
 Since these vitamins are water soluble, they are not stored
in the body like fat soluble vitamins. They dissolve in water
and are excreted from the body in urine. Therefore, it is
important to consume foods rich in these vitamins each
day in order to fulfill the body’s need.
B Complex Vitamins
 Co-enzymes (activate enzymes)
 Found in the same foods
 Single deficiency rare
 Act together in metabolism
 Metabolic pathways used by protein, carbohydrate, and
fat
B Complex Vitamins
Thiamin (B1)
Riboflavin (B2)
Niacin (B3)
Pantothenic Acid
Biotin
Pyridoxine (B6)
Folate
Vitamin B-12
B Complex Primary Functions
 Energy metabolism
 Thiamin (B-1), Riboflavin (B-2), Niacin (B-3), Pyridoxine
(B-6), Biotin, Pantothenic Acid
 Red blood cell synthesis
 Folate, B12
 Homocysteine metabolism
 Folate, B12, B6
Vitamin C
 Synthesized by most animals (not by humans)
 Decrease absorption with high intakes
 Excess excreted
Food
Sources
of
Vitamin
C
 Citrus fruit
 Potato
 Green pepper
 Cauliflower
 Broccoli
 Strawberry
 Romaine lettuce
 Spinach
Functions of Vitamin C
 Reducing agent (antioxidant)
 Iron absorption (enhances)
 Synthesis of collagen
 Immune functions
 Does not prevent colds, but may reduce duration
of symptoms by a day
 Wound healing
 Easily lost through cooking
 Sensitive to heat
 Sensitive to iron, copper, oxygen
Vitamin C Deficiency: History of Scurvy
 Vitamin C (ascorbic acid) deficiency leads to scurvy, a
disease characterized by weakness, small hemorrhages
throughout the body that cause gums and skin to bleed,
and loosening of the teeth. Sailors that were out at sea for
months on end would often develop scurvy unless the
captain had the foresight to pack limes and other citrus
fruits.
 In the U.S., deficiency is seen mostly in alcoholic persons
with poor diets and older persons who eat poorly (no fresh
fruits and vegetables)
Scurvy
Scorbutic Rosary
Follicular
Hemorrhages
Vitamin C Excess
 Hemochromatosis
 Vitamin C enhances iron absorption
 Oxalate kidney stones
 Erodes tooth enamel
24
To determine ascorbic acid (vitamin C) concentration by a redox
titration with potassium iodate
 Ascorbic acid (vitamin C) is sometimes called an .anti-
oxidant. (i.e., a reducing agent!) by pharmacists and
food nutritionists.
 iodometric titrations. In "iodometric" titrations, the
analyte is first reduced with an excess of I-,
producing I2 (actually, I3-) which turns blue in the
presence of starch.
 A suitable method for the determination of vitamin C
(C6H8O6) quantities is a titration with potassium
iodate (KIO3).
 Iodine rapidly oxidizes ascorbic acid, C6H8O6, to
produce dehydro-ascorbic acid,
Object: To determine vitamin C (C6H8O6) by potassium iodate
titration and to master
 Potassium iodate is used as a titrant and it is added to
an ascorbic acid solution that contains strong acid and
potassium iodide (KI).
 Potassium iodate reacts with potassium iodide,
liberating molecular iodine (I2):
 Potassium iodide must be added in excess to keep
iodine dissolved.
 Once all the ascorbic acid has been consumed, any
excess iodine will remain in solution. Since aqueous
iodine solutions are brown in colour, iodine can act as
its own indicator.
 However, it is quite difficult to detect endpoints using
iodine coloration alone, and it is more usual to add
starch, which forms an intensely blue coloured
complex with iodine but not with the iodide ion.
 The addition of acid is necessary to provide the acidic
conditions required in reaction (1) above.
 The endpoint of the titration is the first permanent
trace of a dark blue-black colour due to the starchiodine complex.
 Note: The end point is reached when the solution
turns a permanent, dark blue colour, due to the
complex formed between starch and iodine.
 During an iodometric titration an intermediate dark
blue iodine-starch complex may form momentarily,
before the iodine reacts with ascorbic acid.
 However, if the colour disappears upon mixing, the
end point has not yet been reached.
 Thus, magnetic stirrers or glass rod are employed in
the titration to ensure proper mixing and to facilitate
the reaction of iodine with ascorbic acid.
Iodometric Titrations
 Molecular iodine (I2) is only slightly soluble in water
but adding iodide, I-, produces the "triiodide" ion (I3-)
in solution. Thus, KI is almost always added when
redox reactions of
 I2 are involved in quantitative analysis.
I2(s) + I-(aq)
I3(aq)
Iodine iodide
triiodide
 Starch is used as the indicator in most iodometric
titrations because iodine (i.e., I3)forms an intense
blue colored "starch-iodine complex."
Experiment
Principle
1. KIO3 is used as a titrant and it is added to an ascorbic
acid
solution that contains a strong acid and potassium iodide
(KI).
2. KIO3 reacts with KI, liberating molecular iodine (I2):
KIO3 + 5KI + 6H+ → 3I2 + 6K+ + 3H2O
(1)
C6H8O6 + I2 → C6H6O6 + 2I- + 2H+
(2)
31
 According to the above reactions, each mole of
potassium iodate added corresponds to 3 moles of
ascorbic acid dehydrogenated in the sample.
PROCEDURE
1. Pipette 25 ml of the provided ascorbic acid solution into a 250
ml conical flask,
2. Add  4 ml of 2M HCl,
3. Add  5 ml of potassium iodide (KI) solution and 3 ml starch
solution.
4. Then titrate with the standard potassium iodate (KIO3)
solution until the solution turns intense blue. Write down the
standard potassium iodate (KIO3) solution volume.
5. Pipette 25 ml of an unknown ascorbic acid sample, a kind of
juice, into a 250 ml conical flask, then follow the same
procedure of steps 1-4 and write down the volume of the
standard KIO3 solution determine the concentration (mol/ml)
of ascorbic acid in the selected sample.
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procedure