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In what form is B12 stored in the liver?

Discussion in 'Detox: Methylation; B12; Glutathione; Chelation' started by Bluelude1, Sep 20, 2017.

  1. Bluelude1

    Bluelude1

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    If I consume beef liver what form of B12 am I actually consuming?

    Considering cows are herbivores where would their B12 come from?
     
  2. Alvin2

    Alvin2 If humans were rational...

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    What form is stored in the liver, the evil form :devil:
    Real answer, i don't know, i just couldn't resist :woot:
     
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  3. PinkPanda

    PinkPanda Senior Member

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    In this thread 'methylB12 from foods' there is a list of foods with adenosyl-, methyl-, hydroxocobalamin content.

    Meat and liver have higher levels of adenosyl- and hydroxoB12. Methylcobalamin is found more in dairy products.

    And in humans B12 is stored as adenosylcobalamin in the liver.
     
  4. TigerLilea

    TigerLilea Senior Member

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    Isn't Vitamin B12 produced by bacteria?
     
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  5. veganmua

    veganmua Senior Member

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    They get B12 from the bacteria that produce it living on the grass they consume. But all cows raised for human consumption are supplemented with B12.
     
  6. Bluelude1

    Bluelude1

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    I've heard that the adenosylcobalamin stored in the liver is converted to methylcobalamin as the body needs it. Are there any cofactors that when insufficient can prevent this conversion in people?
     
  7. TigerLilea

    TigerLilea Senior Member

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    Humans need intrinsic factor to absorb B12 in the small intestine.
     
  8. Bluelude1

    Bluelude1

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    Is intrinsic factor needed to absorb all forms of B12 including adenosylcobalamin ? Can it be bypassed via a sublingual lozenge?
     
  9. TigerLilea

    TigerLilea Senior Member

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    I'm going to have to let someone more sciency answer that question for you. My knowledge of B12 is very limited. :confused:
     
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  10. lauluce

    lauluce as long as you manage to stay alive, there's hope

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    I don't know the answer, but if anybody is researching B12, look for this: "functional B12 deficiency". Yo can have, as me, consistently higher than normal B12 as a result of the inability of the body to properly make use of it
     
  11. NotThisGuy

    NotThisGuy Senior Member

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    they are?
     
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  12. TigerLilea

    TigerLilea Senior Member

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    I'll have to check into that as I know when I get tested I am at the very high end of normal. I just assumed that I don't have a problem with B12.
     
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  13. veganmua

    veganmua Senior Member

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    Yup, B12 or just cobalt, which allows the cow's gut bacteria to produce the B12, which gets reabsorbed. Our gut bacteria can do this but as non-ruminants, our intestines are too short for it to get reabsorbed.
     
  14. PinkPanda

    PinkPanda Senior Member

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    This is the cobalamin metabolism where you can see that adenosylcobalamin isn't converted directly to methylcobalamin. The methionine synthase reductase (MTRR gene) needs the cofactors NADPH, S-adenosylmethionine and FAD/FMN (vitamin B2 coenzyme) to convert cob(II)alamin to methylcobalamin.

    If methylcobalamin donated its methylgroup and is converted to cob(I)alamin it can be 'recovered' back to methylcobalamin with copper, zinc and methylfolate.

    "The total amount of vitamin B12 stored in body is about 2–5 mg in adults. Around 50% of this is stored in the liver. Approximately 0.1% of this is lost per day by secretions into the gut, as not all these secretions are reabsorbed. Bile is the main form of B12 excretion; most of the B12 secreted in the bile is recycled via enterohepatic circulation. Excess B12 beyond the blood's binding capacity is typically excreted in urine."
    https://en.wikipedia.org/wiki/Vitamin_B12

    The thing is, when I looked into the issue, I was unable to find the transportprotein that transports cobalamin from the liver back into the rest of the body, but maybe I missed something. Otherwhise, the body might not be able to access liver stores freely and would rely on 'enterohepatic circulation', excretion from the liver in small amounts into the bile and reabsorption in the gut with intrinsic factor.

    Then you have the body stores in the cells but they are also adenosylcobalamin, and since there is no direct conversion from adenosyl- to methylcobalamin, I don't know wether that's always enough.
    That's why I prefer hydroxocobalamin.

    I'm pretty sure the intrinsic factor is needed to absorb all vitamin B12 forms, its just part of the basic vitamin B12 absorption. Sublingual forms are supposed to be able to bypass the intrinsic factor. There is some discussion wether they are as effective as cobalamin injections, you might have to try it out and see how well it works for you.
     

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