Confused about my B12 levels

[unamariececilia]

My B12 was 180 in May and 398 in September at follow up after taking daily supplements (1000). Does this mean I'm absorbing it and should therefore continue supplements? My GP wouldn't give me the active B12 test because she says I am absorbing it if my levels have increased. I know 398 is normal in the UK but not in a lot of other places so if I am able to absorb it, is it worth taking 2000 a day to continue to increase my levels?

[fbirder]

398 is normal, or high normal, in the whole world. It is a myth that various parts of the world have much higher ranges. Here is one such myth from America -

The medical field in Japan and Europe considers a patient to have vitamin B12 deficiency if testing reveals levels below 500 pg/mL to 550 pg/mL.

clancymedicalgroup.com/vita...

Over here people insist on spreading the myth that anybody below 500 is treated in Japan. But this is what the Japanese government say -

"If serum vitamin B12 levels are <200 pg/mL, vitamin B12 deficiency is very likely. If serum vitamin B12 levels are >300 pg/mL, vitamin B12 deficiency is unlikely."

ncbi.nlm.nih.gov/pmc/articl...

According to this UK study - cambridge.org/core/services... - the mean B12 level was 313 pmol/L

As your B12 levels have increased by 220% in 4 months of oral supplements it's very unlikely that you have an absorption problem.

Human absorption of B12 is limited to about 10 mcg at one time, so taking 2000 mcg instead of 1000 mcg isn't going to help. If you want to get more into your system you could take 1000 mcg twice, or three times, a day. That way you can absorb 10 mcg two or three times a day.

[unamariececilia in reply to fbirder]

Thank you! This really helps. Just to give you context, I'm having severe neurological problems including episodes of ataxia where I have needed mobility aids (I'm 32!) With this in mind, is it possible that I have a functional B12 deficiency where there is a deficiency but the levels appear normal?

[fbirder in reply to unamariececilia]

Yes, it is possible. But it's unusual. You can test for methylmalonic acid (MMA) and/or homocysteine (hCys). These are two chemicals used up in reactions mediated by B12. If levels are raised then it's a sign of a possible functional deficiency (there are other possible explanations).

Have you seen a neurologist?

[unamariececilia in reply to fbirder]

Thank you. I'll look into that further. Yes, he says it's all psychological