After reading the FaceBook posting by the PAS about a paper describing a genetic mutation that affects activation of methylcobalamin, but not cyanocobalamin, I decided to try using cyano for my next jab. So I went on to amazon.de and ordered some - only to be told that they could not be delivered to my address!
I checked and found that the hydroxo was still OK, so it's just cyano. I'm guessing that it's because cyano is not licensed for use in the UK.
Anybody know of any reliable source?