Hi there,
Can someone please explain to me why - if you are not able to absorb B12; then taking oral supplements may risk giving falsely high B12 serum readings? Surely if your readings have increased then you have absorbed the vitamin? I can understand not taking Folate if there is a question of B12 deficiency as the extra folate can mask macrocytosis but can’t understand the other logic?
Yes if you are taking oral b12 only and your levels raise you are absorbing it.so good news
Thanks for your response - So why am I reading in all of the B12 help sites that you mustn’t take oral supplements? Eg “B12 injections are required to treat vitamin B12 deficiency when you cannot absorb this complex vitamin from food. This means that oral B12 tablets may raise B12 levels but will NOT be helping to treat your symptoms.” ?
Because you are reading garbage.
If you have PA then you cannot absorb any sort of oral B12.
Some people will try to tel, you that you can absorb B12 via ‘passive’ absorption. There is zero evidence for this.
If we could absorb 1% from the gut, even if we had PA the there would be no need for any of us to have injections.
If you have PA then you cannot absorb oral B12 at all.
If you take oral B12 and your serum levels rise then you do not have falsely high levels. You have truly high levels and you do not have PA.
fbirder, please note that one of the warnings against use of high dose oral is actually provided as a link in the pinned posts
healthunlocked.com/pasoc/po...
as discussed previously there are people with definite diagnoses of PA who find that high dose sublinguals do indeed help them.
There are a number of studies - that I have previously shared on this forum showing that patients with a number of absorption problems - including PA do show rises in serum B12 levels as a result of high dose oral B12.
What is also true is that not everyone benefits or shows absorption from high dose B12 - significant numbers of people don't which is what makes it unsuitable as a blanket treatment as mechanism isn't understood and why some people don't respond also isn't understood. The percentage of people who don't respond seems remarkably constant across absorption problems, meaning that it is unlikely to be related to PA.
It is also well established that serum B12 doesn't necessarily tell the whole story and for many people is meaningless as a measurement post loading doses and that people can actually be B12 deficient well into the normal range anyway.
There are two ways in which people absorb B12 - most absorption is through specialist mechanisms in the ileum.
As well as this there is a mechanism known as 'passive absorption' which occurs elsewhere and exactly how it happens isn't well understood. If you take very large doses of B12 orally then on average 1% of the dose will be absorbed passively. However, 1% is very much an average and for some people it is basically zero. This seems to be completely independent of whether the normal mechanism is functioning properly or not ... and about 20-30%of people seem to have basically no passive absorption.
So, taking very large doses orally may result in enough passive absorption to mask problems with absorption in the ileum. It also by passes mechanisms operating in the ileum that limit uptake and reduce the possibility of excess B12 uptake from a B12 rich diet (raising serum B12 levels above the normal range which, of itself can cause functional B12 deficiency in some people).
If passive absorption happens in 80% people with PA then everybody with PA should be given a trial of high-dose oral B12 instead of injections.
and that is what groups of doctors are trying to do but it needs to be informed consent (which often doesn't appear to be the case) and careful monitoring (which is difficult when there aren't good objective tests)
And it is what groups of doctors should be doing if 80% of people with PA (and even more with other causes of a B12 deficiency) could do OK on tablets.
Oral B12 would be safer, cheaper, and keep serum levels at a more constant level (none of the huge peaks and troughs you get with injections).
I think there is a long way to go before it really becomes a viable option as the first line of treatment for patients with B12 absorption problems - 70-80% means that potentially an average of 1 in 3 patients won't respond. There is currently no way of knowing at the moment which patient that would be so all 3 might need monitoring. Add in the risk of non-compliance in patients with impaired memory and cognitive impairment - given the age profile of B12 absorption problems and that memory and cognitive problems are symptoms of B12 deficiency introduces another risk. Assuming it is a safer and cheaper option ignores a number of factors like these.
I was told that if you have P.A and problems with stomach absorbing then only injections will work and oral medication is more or less useless, that was after a discussion with a doctor and a specialist , there seems to be alot of companies trying to cash in without understanding the problem and or treatment , things like tablets and lozenges etc may be okay if you have a healthy gut and maybe just a little low on b12 .
Thanks for asking this! I've been wondering the exact same thing. I've been given quite a bit of grief on another board for trying oral supplements which according to the 'experts' over there, will do nothing but falsely raise my levels. How do they know this, and why would doctors bother to prescribe them at all if this is always the case?
I think there may be more to high dose oral B12 than meets the eye, and it may be related to cobalamin analogues. A major portion of large amounts of ingested B12 appears to be converted to cobalamin analogues by bacteria in the gut.
pubmed.ncbi.nlm.nih.gov/184...
This article also refers to animal studies that suggested that B12 analogues formed in the gut can move into the liver, and presumably other parts of the body.
People with mainly neurological symptoms of B12 deficiency have been found to have high concentrations of cobalamin analogues in their venous blood.
pubmed.ncbi.nlm.nih.gov/333...
At least one B12 analogue has been shown to bind to intrinsic factor and transcobalamin and cause B12 deficiency (in an animal model).
pubmed.ncbi.nlm.nih.gov/240...
I think research promoted by the PAS found that people who required more frequent B12 jabs had gut bacteria that differed from those who do get away with less frequent jabs.
I also think some total serum B12 tests are affected by B12 analogues.
Conclusion: Inter- and intra-individual variability in B12 analogue production in the gut (due to variations in gut bacteria) may explain variability in response to high dose B12.
Hi, I’m relatively new to all of this
When you refer to analogues do you mean the various forms of cobalamin - methyl, adenosyl, cyano etc?
No. I probably should have used the term "inactive B12 analogues". These are cobalt based molecules similar to the four forms of B12 (methyl, cyano, adenosyl, hydroxo etc) but with small differences that make them unusable by animals. It is thought that one of the functions of haptocorrin is to bind inactive analogues.
Ok so I think I understand what you are saying. So .... in theory if a high dose sublingual B12 is taken on a daily basis (assuming the sublingual absorption is successful - i.e. no reliance on gut or gut bacteria) then this should be as effective as injections?
High dose oral /sublingual methcobalamin worked very well for me from about mid 2006 to sometime in 2013. I think my initial symptoms resolved very slowly compared with how quickly they might have resolved with injected B12. Between 2013 and 2016 the effectiveness seemed to tail off. Oral B12 doesn't work for everyone, but if it does I think it is much better than injected because the cells get a steady supply rather than very high peaks followed by low troughs.
Not sure what you mean by "no reliance on gut or gut bacteria". In a healthy person gut bacteria make small quantities of useable B12 which is not usually absorbed. Gut bacteria converting large quantities of oral B12 to inactive B12 analogues is not a normal situation - it only occurs when very large quantities of B12 are taken orally. Inactive B12 analogues in the blood can interfere with useable B12 and some B12 blood tests.
hi please don't waste your money on b12 supplements if you have pa your body cannot absorb it that is why you have pa in the first place body doesent absorb you have to have injections
The gut absorbs nutrients by passive diffusion from a high concentration to a lower concentration - so if blood sodium concentration is lower than the sodium concentration in the gut sodium will move across the cell membranes into the blood. The B12 molecule is very large and is only able to move very slowly through the membranes - hence the oral B12 is moved along the gut before it can all be absorbed.
To overcome this we have evolved an active transport mechanism - a large molecule in the blood capillaries grabs the B12 from the gut and drags it into the blood. If we have PA this mechanism does not work. The muscles have an extremely rich network of capillaries so when we inject B12 into the muscles it is quickly absorbed and the fluid injected stays in place till it is all absorbed - this gives the high blood B12 peaks that we appear to need to repair nerve damage. It is why I inject into a muscle every other day. If no neurological symptoms are present only then should we accept subcutaneous injections - probably more frequently than bimonthly.
Hence very high content B12 tablets can provide some of this vitamin although not enough to repair nerve damage. It may be that slow release, high B12 concentration capsules will one day replace injections but they are not yet. Neither do we know if very high B12 inside the gut are safe.
Bellabab - I don't think anybody knows at present how passive absorption occurs but I very much doubt it involves the sort of osmotic diffussion that you mention in the reply above.
The science of passive diffusion is very well known and understood. No doubt about that whatsoever.
Oral B12
Best time 2 take B12 orally? Spread it out? 
No PA or B12 deficiency but I am still going to supplement with oral B12 - should i get any other tests before this to rule out for sure?
Confused about oral meds and sub cut injections
