My next-door neighbor called this afternoon telling me that her doctor won't renew her prescription for her B12 injections. She gives herself shots of 1000 mcg cyanocobalamin weekly, although she said she's missed some shots recently. Her level is high (I believe she said 1200), and her doctor told her too much B12 in the blood will damage her liver. I told her I thought this might be a possibility because the liver has to convert the cyanocobalamin to methylcobalamin. As a side note, I give myself monthly injections of 1000mcg cyano and also supplement daily with 5000 mcg sublingual methyl tablets. I gave her sublingual tablets to take, but she hasn't been doing this lately.
Has anyone else heard that too much B12 can damage the liver? If so, can you point me to sources to back this up?
If you have heard that B12 won't damage the liver, could you point to sources to back up this as well?
Nedi in Texas