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The Vitamins


Fat Soluble Vitamins Water Soluble Vitamins procedure * * Maintenance of membranes - prevents oxidation of unsaturated fatty acids contained in the phospholipids ... – PowerPoint PPT presentation

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Title: The Vitamins

The Vitamins
  • Fat Soluble Vitamins
  • Water Soluble Vitamins

Characteristics of Vitamins
  • Vitamins are micronutrients
  • Very small amounts are needed by the body (gt1
  • Very small amounts are contained in foods.
  • Vitamins are essential.
  • The roles they play in the body are very
  • 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
  • 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
Fat-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,
  • sun
  • storage from the summer does not last the winter

function Vitamin D
  • 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

water-Soluble Vitamins
  • 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 bodys 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
  • In the U.S., deficiency is seen mostly in
    alcoholic persons with poor diets and older
    persons who eat poorly (no fresh fruits and

Follicular Hemorrhages
Scorbutic Rosary
Vitamin C Excess
  • Hemochromatosis
  • Vitamin C enhances iron absorption
  • Oxalate kidney stones
  • Erodes tooth enamel

Determination of Vitamin C (Ascorbic Acid)
Concentration by a Redox Titration with Potassium
Iodate (KIO3)
To determine ascorbic acid (vitamin C)
concentration by a redox titration with potassium
  • 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,
  • C6H6O6 C6H8O6 I2 C6H6O6 2I. 2H

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 starch-iodine 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

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

  • 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)

  • According to the above reactions, each mole of
    potassium iodate added corresponds to 3 moles of
    ascorbic acid dehydrogenated in the sample.

  • 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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