There are 2 types of B12 on the market -
Cyanocobalamin - which is a synthetic chemical with a molecule of cyanide
https://www.nhs.uk/medicines/cyanocobalamin/
https://www.ncbi.nlm.nih.gov/books/NBK555964/
and
Methylcobalamin - is derived from natural sources - or more recently when synthesized, more closely matches the natural chemical structure
https://www.healthline.com/nutrition/met...ailability
Methyl - is less stable of the shelf - and probably works better as a sublingual spray but the dissolving Sublingual pills work almost as well
Controversy exist on which type is best
Metyhyl is harder to find and cost usually about 2x as much
Personally - I use Methyl --- have been for years -
The thought of a cyanide ring in a pill just makes me question - although I am sure its not enough to harm
I do know that large prolonged doses of B12 will result in Polycythemia Vera - Too many red blood cells -
Blood testing levels should not go higher than 1000 -- but most docs will not test. Its not uncommon to see some people with levels over 5000 who have cardiac disease. It would be wise to reduce your intake if this was every the case -- too thick a blood is not good for the heart
High levels can also results in exacerbation of GI symptoms, and "pins and needles" in the hands and feet
Highly recommend that anyone on high doses of B12 read up on the literature
Thank you for posting this information --- it is very important stuff.
IBS is a monster and any information about new research and help is good to see