I have been very ill with all the signs of B12 deficiency and not getting any help from doctors as my B12 level is 1,100mg although prior to testing i had NEVER taken a B12 supplement, not even a multi vitamin. Four months ago I began taking large doses of sublingual B12, 5,000 mg tablets, 8 a day, and the improvement in my leg weakness and other neurological symptoms including pins and needles and burning feet and cramps disappeared within two weeks. But then it appears i developed Hypokalemia (low potassium) from the rapid creation of new red blood cells and i became even more ill with heart palpitations, anxiety, breathlessness, dizziness, almost fainting, brain fog, insomnia. I had been taking methylcobalamin B12 and suspect i have some sort of issue with it (over methylation), I stopped taking it six weeks ago and am terrified to touch it again. They new symptoms of breathlessness, weakness, brain fog, anxiety etc remain. Now i have an appointment with a haemotologist, who is taking me into hospital for tests. Although at our first meeting he said i could not be B12 deficient as i had so much of it in my blood. I requested that he considered that i might have functional B12 deficiency and in fairness he did listen. He is going to test for intrinsic factor, as well as organize heart tests for me. I want to ask the lovely members on this forum if intrinsic factor is available as a sole supplement.....i can only find it in tablets combined with methylcobalamin. I think the way forward for me would be to take intrinsic factor and a cobalamin B12 supplement. Sorry if this is long winded and complicated but I am at my wits end. Thanks. J
PLEASE HELP WITH SUSPECTED B12 FUNCTI... - Pernicious Anaemi...
Pernicious Anaemia Society
If oral B12 was helping then it's likely that you don't have a problem with B12 absorption.
Some people have a reaction to methylcobalamin, including me. But I only react to injections, not methylcobalamin tablets or sublingual lozenges. That shows that I don't absorb methylcobalamin. The fact that you do react to the oral form means that you must be absorbing it. I would just switch to another form. Cyanocobalamin is just as good, if not better.
So I doubt you have a functional deficiency. However, if you want to test for it you need to ask for an MMA blood test (and a homocysteine test, if you can get one). These are two chemicals used up in reactions mediated by B12. If you have high blood levels, but it's not getting into the cells (the definition of a functional deficiency) then both MMA and hCys will be raised.
thanks so so much, but i took methylcobalamin as i undertood that does not need intrinsic factor to be used by the cells, whereas clobalamin does? Can you shed light on this? thanks again. J.
There is a lot of rubbish on the Interwebs about methylcobalamin, so I'm not surprised you're confused.
All forms of B12 (methyl, cyano, hydroxo and adenosyl) need IF to be absorbed from the gut.
Once it enters the blood B12 (from now on I'll use B12 to mean all four forms) binds to one of two proteins - haptocorrin (HC) or transcobalamin (TC). Nobody's quite sure what the point is of the HC-B12.
To enter a cell the B12 needs to be carried in by a protein (like it needs IF to get carried out of the gut). That protein is TC. TC-B12 makes up about 20% of the B12 in the blood. The normal serum test measures both HC-B12 and TC-B12. The active B12 test only measures TC-B12.
Once the TC-B12 enters the cell the TC is removed, then the top ligand (the methyl, cyano, hydroxo or adenosyl) is removed to form cob(II)alamin. That means that all forms of B12 are, from that point onward, identical. So there is no benefit in taking methylcobalamin over other forms.
It's not clear why some people have an adverse reaction to methylcobalamin in large amounts. It's been suggested that it may be because of a mutation in a certain gene for a particular enzyme important in neurotransmitters.
thanks so so much..I will swap to cyano...i got MTHFR testing done and have the 12868c mutation so wonder was that the problem with taking Methyl....it really has been a horrendous experience! Your help is so appreciated. J
No, there is zero evidence for that mutation having any effects at all. The only mutation that might is homozygous for C677T. Even then taking methylcobalamin makes no difference. As I said, all forms of B12 are identical when they enter the cell. With that mutation taking methylfolate might help.
Here's a diagram.
may i ask what your reaction to the Methyl form of B12 was? and was there any explanation for it? thanks again. J
The effect was quite rapid. I felt very, very jittery and anxious. I felt 'wrong' in a way that was impossible to describe, but it really wasn't pleasant.
I never told a doc about the reaction (he's not too keen on me injecting hydroxocobalamin, would be even less so if I told him I was injecting something that wasn't licensed at all). I just gave away the other 9 ampoules.
I can't find the info that made me think it was a problem with the COMT enzyme. There is just too much nonsense on the webs to try and find something that looks like it's not total BS.
thanks again....you so good.....same here....an impossible awful reaction to describe....initially good and then the mother of all horrors, like you don't own yourself any more. J
normal B12 absorption always requires intrinsic factor regardless of the form of B12 being taken. intrinsic factor combines to the whole B12 molecule regardless of whether it is cyano, hydroxo, methyl ...
there is a lot of misleading hype that methyl is a more natural form because it is one of the types of B12 used inside your cells. However, this is irrelevant as the process of getting it into your cells involves removing the cyano/hydroxo/methyl element and then recombining with either methyl or adenosyl when it is inside the cell.
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