Gee, now I'm worried I take too much B12. I take 2000 mcg daily plus whatever is in the multivitamin that I take. I had felt terribly weak in my legs a few years ago, sometimes I had to just sit down on the floor they were so weak. I'd gone to the doctor and they'd done heart stress tests but everything was okay.
So they prescribed a heartburn medicine because also that stomach spincter muscle was being weak sometimes, like I'd bend over and stomach contents would push right up my throat. Also the other end had some weakness episodes but I didn't mention that to the doctor (too embarrassing).
The antacid drug didn't do anything at all except cause headaches.
So I stopped taking the antacid, and started researching on my own. I increased salt and it seemed to help a little, then I started taking B12 and that seemed to help a lot but things weren't perfect, there was still some mild weakness. Then the dental hygienist told me that B12 plus Iron had helped her mother's weakness. So I added a little iron, and since then things have been almost always back to normal.
I changed doctors and told the new doctor that I was taking 2000 b12, and he did a blood test for B12. I had plenty in my blood, but he said to keep taking the B12, so I guess he felt the level was okay.
Maybe I'll try tapering off to 1000 mcg.