A word of warning to anyone taking high potency B complex or drinking lots of energy drinks! I experienced quite severe balance problems and ended up in hospital for nerve tests and an MRI. I kept on telling everyone I needed a B12 shot, which they didn't give me as my level was in the 800's. It wasn't until I left hospital and I got some results from my doctor and saw that my B6 levels were extremely high-I'd been taking a high potency B complex. After some research, the neurologist made a diagnosis of B6 toxicity, which has very similar symptoms to B12 deficiency-hence me thinking that was the problem. My B12 tends to be on the low side but I think many of the symptoms I have experienced over the past few years have been related to taking B6 on and off.