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Vitamins and minerals Learning objectives

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					                  Vitamins and minerals
                   Learning objectives
Understand why V/M are essential to healthy living;
Understand that there are healthy intake levels for V/M and
 that excesses may be worse than deficiencies;
Know the four fat soluble vitamins and basic roles;
Know the water soluble vitamins we discuss in class and their
 roles;
Know the roles of the minerals we discuss in class;
Know that processing and storage may affect some vitamins
 more than others.
What is wrong with “If a little is good, more must be better”?
                    Fat soluble vitamins
                           ADEK
Dissolve in organic solvents – methanol, gasoline etc..
Can build up because they are not excreted
Absorbed during fat absorption
Transported in lipoproteins

Vitamin A – carotenoids and retinoids
Vitamin D – cholesterol product
Vitamin E – tocopherols
Vitamin K – menaquinones and phylloquinones
                           Vitamins

Essential organic substances
Yield no energy, but facilitate energy-yielding chemical
   reactions
If absent from a diet, it will produce deficiency signs and
   symptoms
Preservation of vitamins in foods
    exposure to light, heat, air, water, and alkaline
                         Vitamin A

Two general types
 Pre-formed
     retinoids are found in animal products

  Precursors
      carotenoids are found in plant products
            beta carotene, lutein, lycopene, others
      must be converted to retinoids
      absorbed and converted by intestinal cells
                 Absorption of Vitamin A

Requires bile, digestive enzymes, integration into micelles

Dependent on the fat in the diet
  olestra
90% of retinoids can be absorbed

Only ~3% of carotenoids are absorbed
 so eat your carrots

Intestinal cells can convert carotenoids to retinoids
                 Transport in body/storage

Liver stores 90% of vitamin A in the body
  polar bear liver
Reserve is adequate for several months

Transported via chylomicrons to the liver

Transported from the liver as retinol via retinol-binding
  protein to target tissue

Carotenoids can be transported via VLDL
                  Functions of Vitamin A

Night and color vision
  xerophthalmia
Cell health and maintenance
  epithelial cell differentiation and division
  cells deteriorate without Vit A
  follicular hyperkeratosis
Antioxidant
Macular Degeneration
  lutein
The vision cycle
                  Sources of Vitamin A

Retinoids - animals
  Liver, fish oils, fortified milk, eggs
  50% of vitamin A intake is from these sources

Carotenoids - plants
  dark green leafy
  yellow orange
  the other 50%
                 Overdose of a Vitamin?

High doses of vitamin A are toxic
  HYPERVITAMINOSIS A
      3 – 10x supplements
  Teratogenic – birth defects/spontaneous abortion
      3x RDA
  Carcinogenic – some feeding trials with smokers
      3 – 10x RDA
  Fatal dose – 12 gram
                How much do we need?

International unit (IU)-crude method of measurement
Retinol activity equivalent (RAE) -current, more precise
  method of measurement
  1 ug of retinol = 1 RAE = 3.3 IU =12 ug beta-carotene =
      24 ug of other provitamin A

RDA
  900 REA men           700 REA women
Supplement or no?

				
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posted:3/31/2008
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