Thyroid UK

How much B12 for me?

I think I would benefit as I have signs of forgetfulness, anxiety, stress and am snappy and moody! I would like to get back to feeling normal and being my nice, laid back self...

My B12 (9 June 14) was 438 (180-800)

My B12 (17 Feb 14) was 411 (180-800)

I know my doctor will not help with this!

My questions are:-

How much should I take?

How often?

Do I need to take anything else with it?

Does it need to be taken separately to the ferrous sulphate I currently take 3 x daily?

Thank you everyone!

(P.S... I have low "but in range" folate) ie, 7.9 (3-20)

Thanks again...

16 Replies

Yes you can supplement with B12, it has to be methylcobalamin and you can buy sublingual tablets or a spray. Excess is excreted but take note of the instructions on the box, it will have advice on amount.

As it is sublingual, it doesn't affect any medications you take by mouth.

This is a link re magnesium which is also necessary.

Magnesium can be absorbed through the skin. You gradually work up till the 'tolerence' test, i.e. it makes you go to the bathroom very quickly. So you lessen the dose.


Thank you shaws for the link. I have been researching magnesium too and I'm keen to try it. Would it be ok to PM you? I have a question regarding magnesium but don't want to break the advertising guidelines?


Yes, of course and if I am able to answer I will.


How much elemental magnesium should be taken? I've seen recommendations of anywhere from 300mg to 600mg. I have some 100mg elemental magnesium citrate tablets, but I don't really want to take 6 of these per day, as that's going to become expensive very quickly!


400mg, I've been on it for 20 years, and take mine at bedtime. Magnesium citrate is a laxative, I use (Solgar's) chelated magnesium.


I cannot answer your question but this is a good article which may answer your question.

This is an economical DIY recipe for a spray:


Your B12 is VERY low. Only about 20% of the amount shown in the blood test actually reaches the cells where it is needed. Anything under 500 can contribute to neurological symptoms - as you have mentioned. Sally Pachlok has mentioned that B12 should be around 1000 to prevent cognitive decline in the elderly In Japan the range STARTS at 500 and goes up to 1300. All information contained....

What a pity your Doctor is not well informed....

How is your Iron and Ferritin ? Your Folate will probably improve when the B12 increases. You will need to take Folic Acid when you start taking B12. Jarrow Methylcobalamin 1000 mcg - chewable works well.


Hey Marz. Every time I read your posts I become impatient waiting for the results of my MMA and homocysteine levels. As if 440 is low, my 182 is pants! The doctor isn't going to give me injections despite my showing him the guidelines, so I'm waiting for the results so I can supplement myself.

I'd like to get my levels up to 1000, do you recommend the 1000mcg, or 5000 mcg tablets?

Thanks :)


I would say the 5000 mcg as you are so low. Then 1000mcg for maintenance. Once you are taking B12 the tests are not meaningful. Have you had other tests to rule out PA ? Hope you get your results soon.... :-)


I was told that my anti-intrinsic factor came back as negative, although I didn't see the results.

Usually I buy any vitamins and such like through a site called Natures Own, or Cytoplan (they are the same website, just one aimed a the public and the other at GPs and practitioners, although I order from both). However it appears their B12 is only 500mcg per tablet, so that's a big difference. I think I'll order then 5000 now and it should be here by the time the test results come in hopefully later in the week.


Don't forget to take Folic Acid with the B12 as they work together in the body. Sorry if I am repeating myself....there seems to be lots of B12 posts lately :-)


Hi Marz. My last serum ferritin on 9.06.14 was 33 (25-300) and full blood count showed everything 'in range'. Thank you for your help with the above.


'In range' can still cause symptoms Polly.

Re B12, I know of a woman who was bed-bound with a 'normal' reading of 500 also another woman with neurological symptoms with a B12 of 485.


Ferritin needs to be around 80/90 - so the store cupboard for Iron is almost empty :-) How was the MCV on your Full Blood Count - was it high ? Being in range - as sazzyb says - in range is not really good enough. Needs to be near the TOP of the range....


Hi Marz, sorry for late reply. My MCV was 90.9 fL (76-96). Is that high enough? By the way, thank you for responding, Pollydolly.


I'm not so well informed on the detail regarding MCV. I do know they raised the upper limit - not sure of the consequences. Mine was 93 and told it was high by someone who knows more than me. You could click onto posts by hampster1 who is very well informed.... maybe there is something about it on the B12 deficiency website I posted a couple of days ago....


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