Pernicious Anaemia Society
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Oral B12 - with food or not?

I usually inhabit the Thyroid UK community on HU - and have suggested to several people that they should post here as we see so many B12 issues.

We see people with relatively low B12 levels who seem to improve on high dose oral B12 (e.g. 1000 mcg methylcobalamin) - though some do get at least some shots. But when they try oral B12 there seems little guidance on whether to take it with food - or away from food. My thoughts are:

o... Even if someone is trying to go down the sub-lingual route, a fair proportion of the B12 will likely be swallowed;

o... The absorption of B12 using high-dose oral sources depends upon achieving a high concentration of B12 in the gut;

o... You will get a higher concentration if the B12 is taken well away from food.

So I am inclined to think it best to take well away from food. But in so many situations what seems likely,or even plain-as-a-pikestaff-obvious, actually isn't. And I have not managed to locate any research into this question.

So with food? Or well away from food?


7 Replies

It is important to distinguish between "oral" and "sub-lingual. You use both terms as though they were interchangeable: they are not. Sub-lingual is exactly that, and it is important to make the tablet dissolve as slowly as possible under the tongue. Oral supplementation is when the tablet is swallowed, but along with food. This important distinction is made clear by Kevin Byrne in his "The Enterohepatic Circulation of Vitamin B12", Professional Version. This is available from the Downloads section of the Pernicious Anaemia Society, but I think membership of the PAS is necessary before it is available.

Sub-lingual B12 can be taken at any time, for efficient application of the method must necessarily be independent of food intake but can be right after food intake, in my experience, having used the sub-l method very successfully. Efficiencies of as high as 15-25% can be achieved, depending on the size of the dose, for large frequent doses are needed, (I took 25,000 -30,000mcg daily spread throughout the day) and the careful and slow way the person allows the sub-lingual method to take place so that slow absorption through the sub-lingual membranes occurs. No crunching to "speed things up" - it does not work like that.

Oral supplementation is with food so that it is travelling with the bolus and so raises B12 in the ileum to a higher level than that in the ileal cells and absorption is by diffusion. Diffusion is when there is a concentration gradient between the outside and inside of a cell and so migration of B12 into the cell through its wall takes place but only when a steep diffusion gradient is established.

Oral administration he says is poorer because it uses three separate diffusion routes, whereas sub-lingual though involving many routes can be better and influenced by the person's way of dealing with the tablet .

I trust this is clear. The dissertation (Professional Version) by Kevin Byrne is fascinating and makes excellent reading.


Thanks - your response is appreciated.

I am sorry if it looks like I am confused. Don't think I am - but I do suspect that a significant proportion of an attempted sub-lingual dissolve/absorption will nevertheless go down the throat.

What happens if you take an oral tablet well away from food?

Kevin's paper is accessible - thanks.



Now there's a question. I think we shall have to ask Kevin Byrne that one!


Hi Helvella

Personally I tried taking B12 tablets at 50 micrograms three times a day and found they had little or no effect and were not well tollerated, I then after a 3 week clear period took Cytacon B12 tablets, which are the licenced form and with that I also took B1 + B2 + B3 + B6. The science being that B2 would help to activate B6, which would be needed to absorb B12. The B complex of B1 + B2 + B3 + B6 was taken in a tablet produced by Activis under the name of "Vitamin B Compound Strong Tablets" I took 1 of each tablets twice a day, one in the morning after breakfast and one after my evening meal. The basic idea being to mimic slow release tablets, which seem impossible to obtain in Britain, in this way I was allowing more time for the small intestine to absorb the B12. Bingo!! it worked and was very well tollerated, I managed to raise my serum B12 from 131 to 478 in less than 8 weeks. I would however hasten to add, that I had taken TTG - Intrinsic Factor and Parietal Cell Antibody tests prior to taking the above, all those tests came back as NEGATIVE.

Hope this may help in some way


B12 Turbo

1 like

It certainly helps in increasing my appreciation of things around B12!

Many thanks.


Thanks for the further information on how to raise B12, this is very interesting.


My doctor has me taking Sublingual B-12 under my tongue every morning before I have coffee or food. The directions say to keep it under your tongue for 30 seconds but I try to keep it there longer for better results. Oral B-12 does nothing for me. I've tried the B-12 Patch and that doesn't work either. Sublingual without food seems to work the best for me.


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