Vitamin Cobalamin

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					Vitamin B12
     Group 3:
  Giselle Garces
   Kristen Kohn
  Ryan Malloney
Vitamins- organic molecules required only
   in trace amounts that must be obtained
     through diet. Vitamins are a dietary
  necessity for humans because we do not
     have the ability to synthesize them.
         ( source: our favorite textbook)
           Vitamin B12
 Part of the complex of B vitamins, vitamin
  B12 is one of the most intricate vitamins.
 It is water soluble!
 Vitamin B12 is bound to the protein in
  foods. During digestion, HCl releases the
  B12 from the protein and it combines with
  Intrinsic Factor before being absorbed into
  the bloodstream.
What Does Vitamin B12 Look Like?
Where You Can Get Some Vitamin B12!

 Mostly animal products:
      Meat
      Fish
      Eggs
      Milk and Milk products like yogurt
 Some foods that are not natural sources are
  fortified with Vitamin B12:
      Breakfast Cereals
      Bread
    So, This Thanksgiving…
   Mashed Potatoes
   Cranberry Sauce
    Deviled Eggs
    Pumpkin Pie
****Which of these
 will provide you with
  plenty of vitamin
*** Given the sources, who
do you think might be at the
greatest risk for Vitamin B12
 Vegetarians (especially

 Elderly

 People with gastro-
 intestinal damage
                Fun Fact #1!
• Vitamin B12 is excreted in bile, but the body is
  able to reabsorb a large percentage. People who
  consume diets very low in B12 may actually be
  reabsorbing more than they absorb from diet.
  This is why it can take up to 20 years to show
  symptoms of deficiency in people who have
  recently changed to low-B12 diets. If there is a
  complete absorption failure, however, deficiency
  symptoms can occur in 3 years.
                   Fun Fact #2!
• A study done of a group
  of Iranian vegetarians
  revealed that they
  consume adequate
  dietary B12 from
  unwashed fruits and
  vegetables fertilized with
  human manure. Human
  feces contain significant
  amounts of vitamin B12.
   To use B12, our body requires 5 peptides
    to deliver it to appropriate tissues and 4
    enzymes to reduce it to a form where it
    can be functional. Therefore, it is
    necessary to get sufficient B12 from the
    diet to prevent deficiency.

So….should we raise the RDI???
          Should We Raise the RDI?
 Many researchers recommend raising the current RDI
  for B12 in order to prevent developmental abnormalities
  and diseases of old age.
 Another argument for raising the RDI comes from
  recent evidence that B12 may help prevent cancer:
       There is evidence that common SNP alter proteins responsible for
        absorption, transport, and metabolism of B12 and folate to their active
        forms. Decreased efficiency requires more B12 to meet body’s needs.
       B12 also has been shown to prevent chromosomal damage, therefore
        leading to increased genomic stability and decreased cancer risk,
        regardless of exposure to carcinogens.
                       Current RDIs
Life            Men             Women           Pregnant Lactating
19+             2.4 mcg         2.4 mcg

All Ages                                        2.6 mcg         2.8 mcg

Results of two national surveys, the National Health and Nutrition Examination
Survey (NHANES III-1988-91) (8) and the Continuing Survey of Food Intakes
by Individuals (CSFII 1994-96) (7) found that most adult men and women
consume recommended amounts of vitamin B12 (6-8).
B12 Deficiency
 Macrocytic Anemia

 Neuropsychiatric Symptoms (esp. in

 Chromosome Damage
                 Fun Fact #3!
Folate (Folic Acid) can mask signs of B12 deficiency
  because it can correct macrocytic anemia, which
  is often the first symptom experienced in B12
  deficiency. The folate won’t correct the
  deficiency, however, and because it goes
  undetected severe nerve damage can occur.
        Macrocytic Anemia
-Macrocytic means red blood cells that are
  larger than normal
-Macrocytic Anemia is caused by retarded DNA
  synthesis, which is the result of B12 deficiency
  because B12 is required for thymidylate and
  purine synthesis.
-B12 Toxicity can lead to polycythemia, or
 overproduction of red blood cells. This is
 indicated by a hematocrit over 50.
Neurological Effects
   B12 is important in the synthesis of fatty
    acids that are required for formation of the
    protein Myelin. Myelin is the biggest
    component of the Myelin Sheath (yes, hence
    the name) which surrounds and serves as
    insulation for nerve fibers. (disintegration of
    these sheaths is also responsible for Multiple
                Fun Fact #4!
• Exposure to Nitrous Oxide can cause B12
  deficiency in cases of abuse, anesthesia usage
  during surgery, or occupational exposure for
  hospital workers.
• NO actually inactivates B12, so while those
  affected have enough in their system, they are
  effectively B12 deficient.
Chromosome Damage

   There is evidence that vitamin B12
    deficiency damages the chromosomes in
    white blood cells, leading to reduced
    numbers of white blood cells which in
    turn causes immune system problems.
           So, In Conclusion…
• Eat lots of turkey and egg or dairy products this
  Thanksgiving (I suppose eggnog counts)
• Make sure your grandparents do the same
• Corner any vegans or vegetarians present and tell
  them to stock up on fortified foods and look into
  dietary supplements. Tell them scary results of
  deficiency that you learned in biochem.
• Offer to help fertilize their fruits and veggies if they
  don’t seem inspired to follow your advice.
    This goes to the Vegetarian Society’s
    B12 info sheet.

• - This is where
    we got the structure of B12 pic.

• -    General B12
    info from the Vegetarian Resource Group

• -
    Facts About Vitamin B12 from the National Institutes
    of Health
   Petchkrua, Wannapha et al., “ Prevelance of Vitamin B12 Deficiency
    in Spinal Cord injury” Archives of Physical Medicine and
    Rehabilitation Vol. 84 Issue 11. 1675-1679

   Fenech, Michael. “The Role of Folic Acid and Vitamin B12 in the
    Genomic Stability of Human Cells.” Research Fundamentals and
    Molecular Mutagenesis, Vol 475, Issue 1-2. 57-67

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