Vitamin B12 (Cobalamin)

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Vitamin B12 (Cobalamin)

• Group 3
• Giselle Garces
• Kristen Kohn
• Ryan Malloney

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• 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)

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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.

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What Does Vitamin B12 Look Like?
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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

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So, This Thanksgiving

• Turkey
• Mashed Potatoes
• Cranberry Sauce
• Deviled Eggs
• Pumpkin Pie
• Which of these will provide you with plenty
  of vitamin B12?

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• Given the sources, who do you think might be
  at the greatest risk for Vitamin B12 deficiency?

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• Vegetarians (especially Vegans)
• Elderly
• People with gastro-intestinal damage

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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.

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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.

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• 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???

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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 bodys 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.

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Current RDIs
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B12 Deficiency

• Macrocytic Anemia
• Neuropsychiatric Symptoms (esp. in Elderly)
• Chromosome Damage

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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 wont
  correct the deficiency, however, and because it
  goes undetected severe nerve damage can occur.

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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.

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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 Sclerosis)

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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.

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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.

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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 dont seem inspired to follow your advice.

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References

• http//www.vegsoc.org/info/b12.html
• This goes to the Vegetarian Societys
• B12 info sheet.
• http//www.ce.udel.edu/pei/b12.html - This is
  where we got the structure of B12 pic.
• http//www.vrg.org/nutrition/b12.htm - General
  B12 info from the Vegetarian Resource Group
• http//www.cc.nih.gov/ccc/supplements/vitb12.html
  - Facts About Vitamin B12 from the National
  Institutes of Health

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References

• 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