Comparative effects of hydroxocobalamin and cyanocobalamin on plasma homocysteine concentrations in end-stage renal disease
This issue of cyanocobalamin has come up once before a few years back, but it was enough to give me cause for concern.
The study suggested that cyanocobalamin actually inhibited one of the enzymes it was supposed to be helping.
This study did not look at this enzyme affect, but it did find a much stronger effect of raising cobablamin levels in the bloodstream with hydroxy vs cyano (40 fold increase vs 10 fold increase).