Vitamin B12, also called cobalamin, is a water-soluble vitamin.
Vitamin B12 has a low potential for toxicity if taken in little bit excess above the recommended level.
According to IOM "no adverse effects have been associated with excess vitamin B12 intake from food and supplements in healthy individuals". AND
"There is not sufficient scientific evidence to set a Tolerable Upper Intake Level (UL) for vitamin B12
at this time."
Kindly click the link below for more information.
[The link given above contains the detailed amount of information on this vitamin B12 and also on Folic acid.]Vitamin B12 Toxicity
With Folic acid, also risk of toxicity is low . Please click the link below to find out more.But High doses (above 15 mg) can cause stomach problems, sleep problems, skin reactions, and seizures. Folic acid supplementation can mask vitamin B12
deficiency, which can cause permanent damage to your nervous system. Folic acid supplementation should always include vitamin B12
I hope, it helps.
But I request you to kindly discuss with your treating doctor about these facts and findings before taking Vitamin B12 and Folic acid above the recommended levels. Your treating doctor should be informed before doing so
If you have any other query, please feel free to ask.