Folic Acid Masking Vit B12 deficiency?

[coreytayloris]

Via what mechanism does folic acid mask the effects of vitamin b12 deficiency.
I've read it counters the megaloblastic anemia caused by b12 deficiency?
But folate is involved in dna synthesis, and b12 in rbc production...
Where's the cross over?

[Sorry, im sure this is a basic enough question; I'd hazard this is some biochemical mechanism. Biochem is pretty non existent in our school ]

thank you all

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[DoctwoB]

Via what mechanism does folic acid mask the effects of vitamin b12 deficiency.
I've read it counters the megaloblastic anemia caused by b12 deficiency?
But folate is involved in dna synthesis, and b12 in rbc production...
Where's the cross over?

[Sorry, im sure this is a basic enough question; I'd hazard this is some biochemical mechanism. Biochem is pretty non existent in our school ]

thank you all

Folic acid deficiency and B12 deficiency have the same problem in regards to RBC production. This problem is less folate = less thymine = less/larger RBCs.

Why folate does this is obvious. B12 does this because it catalyzes the reaction from homocysteine to methionine, which is also a reaction that converts Methyl-tetrahydrofolate to tetrahydrofolate, which is the active form used in DNA synthesis.

B12 also catalyzes the methylmalonyl-CoA to succinyl-CoA reaction. No b12 = this rxn doesn't occur => methylmalonyl CoA builds up => its precursor propionyl CoA builds up. excess propionylCoA causes neuron demyelination, which is why you get the neuro Sx.

Thus. If you have B12 deficiency, you'll have neuro Sx and anemia. Giving folate will fix the anemia (mask the reaction that isn't occuring due to lack of B12) but not the neuro stuff.

 

[rollelephants]

if i'm not mistaken, giving folate in a B12 deficiency (thinking it's a folate deficiency) will exacerbate the neuro sxs as well, so you have to rule out b12 deficiency first.

also what Doctwob is saying is called a folate trap...i'm sure if you google that you'll get some good info

 

[DoctwoB]

if i'm not mistaken, giving folate in a B12 deficiency (thinking it's a folate deficiency) will exacerbate the neuro sxs as well, so you have to rule out b12 deficiency first.
/QUOTE]

Are you sure this is true? I was always taught that there were no adverse effects to folate administration in B12, just that you might miss the Dx and have subsequent neurologic problems from continued B12 deficiency.

 

[rollelephants]

if i'm not mistaken, giving folate in a B12 deficiency (thinking it's a folate deficiency) will exacerbate the neuro sxs as well, so you have to rule out b12 deficiency first.
/QUOTE]

Are you sure this is true? I was always taught that there were no adverse effects to folate administration in B12, just that you might miss the Dx and have subsequent neurologic problems from continued B12 deficiency.

i can't remember exactly but i see what you're saying...that makes sense

 

[iheartmints]

Sorry I read your question wrong sorry and doctwob already answered

 

[coreytayloris]

thanks guys!

 

[rocketbooster]

Also, the mechanism for folate treating the megaloblastic anemia is different in B12 deficiency vs. folate deficiency. The person above explained how B12 is involved and only one pathway that folate enters the thymine cycle. That is not the same way folate corrects for the anemia in B12 deficiency. The actual mechanism is folic acid is converted by folate reductase to dihydrofolate, which is then further converted by folate reductase to tetrahydrofolate. That's the way folate feeds into the thymine cycle during B12 deficiency. Normally, folate can feed in either that way or the B12-enzyme route.