Vitamin B 12

25 03 2009

Vitamin B 12

These compounds are actual called “corrinoids” because of the “corrin” ring, which has the center atom, Cobalt.

It was the last vitamin to be discovered. Yet, I am hopeful that there could me more in the future!


The only source of Vitamin B 12 for humans is from animals. Animals derive their B 12 stores from microorganisms. So any B12 associated with a plant is due to contamination via animals. Fermented soy does NOT contain Vitamin B 12 nor does Algae.

Meat and meat products and eggs are the best sources, followed by dairy.

** I think this is particularly interesting. I am speculating on this but if you tend to eat alot of meat products and eggs, you may be “craving” Vitamin B12. I think personally, I usually feel like I need more meat and eggs.  These foods are also high in protein ( which are amino acids bound together). B12 aids in amino acid digestion, so that may be yet another reason why I like to eat a higher protein diet. I also tend to feel much more energetic and like myself if I take a Vitamin B supplement. Interesting coincidence or insufficent Vitamin B12 ? We’ll see**

B 12 is easily destroyed in the microwave. Shoot, I was going to go nuke some right now. Ah well. 

And you will often see “cyanocolbalamin and hydroxocobalamin”. This is the form of B12 used in supplements.

Digestion and Absorption:

The precise mechanisms of digesting and absorbing Vitamin B 12 in your body are poorly understood ( so it could be that I cannot metabolize/digest/absorb B 12 properly !?! ) 

Vitamin B 12 in food is bound to polypeptides, this bond is broken by the gastric enzyme Pepsin, allowing B 12 to be released.

Once B 12 is release, it requires 2 proteins for absorption: 1. Intrinsic Factor and 2. R-protein.

These proteins will bind to B 12 at different points, travelling to its finally absorption receptors in the ileum.

B 12 has to bind with (3) other molecules for it to be transported around the body- these molecules are called “transcobalamins” or TCI, TCII, TCIII

Unlike the other water soluble vitamins, B12 is actually stored in the body for long periods of time…. up to YEARS in the liver. This is why deficiency is so rare, even in vegetarians. If you became a vegetarian at say age 18, it would take 20-30 years for your body to be rid of all its vitamin B 12 stores.  ( so back to my theory:  maybe I am not deficient in B 12 but rather have an insufficent absorption of it? )

Why do we need B 12?

– We use B12 to recycle homocysteine ( a bad guy that has shown to increase risk of cardiovascular disease) back to an amino acid, Methionine.  We also need folate for this recycling.  I talked about this on my Protein Post Here

– We use B12 as a coenzyme for tons of important reactions in our tissues.

– We use B12 for oxidation that eventually leads into the Krebb’s cycle, which gives us our energy. ** I am sure you are aware of the loads of energy drinks out there. I am excited to be getting a sample of Guru Energy drinks, but if you ever have looked at the ingredients.. Most energy drinks contain a high dose of B-vitamins along with some caffeine ( usually only as much as a cup of coffee). The Vitamin B’s DO help give us ATP because they are used in our energy production cycle.

Why aren’t we deficient?-Aside from storing B12 in the liver unlike other water soluble vitamins, we lose very little B12 each day, usually around 0.1 % and most is through bile excretion.


Daily Needs:
– 1 microgram per day appears to be adequate for adults and to prevent deficiency.
– DRI = 2 micrograms per day

– There is evidence some adults ( especially those over 51) absorb little B12. Somehow the mechanisms of absorption do not properly work, thus, the B12 bound to the food is not cleaved by Pepsin- and not absorbed.

– Inadequate absorption NOT inadequate dietary intake is responsible for B12 deficiency!

– A strict vegetarian diet can produce a deficiency, but symptoms may not appear for 20 + years.

– A clinical deficiency is actual rather common ( so my theory is right!)

– A common cause to the deficiency could be an autoimmune disorder. ( well , I don’t have one of those so maybe not.)

-Diseases related to deficiencies

  • Megaloblastic Anemia
    • 1/3 people with this show no signs of it
  • A B12 deficiency can cause a Folate Deficiency, yikes!
  • Spinal Cord Degeneration
    • B12 is needed for amino acid metabolism ( one amino acid is that in the myelin protein, creating myelin sheath around nerve cells).
    • Without B12, nerve cells could be demyelinated- such a severe effect that it could cause death

People at risk for these usually include: high chronic alcohol intake, gastrectomy patients ( they lose the two proteins in the stomach that bind to B12 for absorption), and the elderly.

My thoughts:
What about my theory? Since little is known about the mechanisms of digestion and absorption, how can we assume that we will not be deficient of B12 even if we do not consume any for 20 years? If we know in some adults, their absorption is messed up, it could very well be messed up in others also?

– If the only source of B12 is animals, how do vegetarians get their B12? I am sure there are supplements out there that say ” vegan” but they cannot truly be “vegan” , right? Because B12 is a by product of animal-microorganism reaction.  It is at least a debate I feel and obviously far from consuming a “hunk of meat” but if you want to get picky…

– Disclaimer Once Again:
  This information above is from my notes during my Vitamins, Minerals, and Nutraceuticals graduate level course. This is based on my understanding of these notes and should be not used as medical advice in any sense. If you feel you are in need of help with Vitamin deficiency or toxicity, please consult a physician or seek other medical treatment.




11 responses

25 03 2009

Interesting stuff.

25 03 2009
Lesley Borger

This makes me wish I was in a class that tought me these things … someday I’d like to be! : ) But in the meantime, thanks for sharing!

25 03 2009

love all the nutrition info girlie 🙂
hope your having a great day!

25 03 2009

hmm interesting. So if you go veggie, you should really be taking some sort of B12 supplement huh? Good info! Thanks for posting

25 03 2009

YEARS in the liver?? Holy crap!

25 03 2009

Do you know if B12 in the whole egg or just in the yolks or whites?

25 03 2009
Lara (Thinspired)

I think I have heard that the B12 is mainly in the yolks, but I could be wrong…

This is great info! The most interesting part for me is that it is destroyed in the microwave…yikes!

25 03 2009
Hangry Pants

You’re so smart!

26 03 2009
Sarah W.

nice on the b12 – I take a supplement, and if its not vegan, who cares, I’m getting an essential vitamin that I can only get by consuming animal products and I would rather not

26 03 2009
Patricia Kelly

This B12 info was so helpful. I didn’t realize the only source of B12 was animal protein! My goodness my goodness..I LOVE learning form my kids!
( yep, this is Laural’s mom;) I’m so proud of her.

27 03 2009
Calling all Interviewees… « Body Mind Soul

[…] this it tough! Let’s see I posted about Vitamin A and Vitamin B 12 but I already knew some of that information. I did not know that when athletes consume a high […]

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