It was trial and error, trying this form, then that, then this, then going back to that...along with the various b12's, and various amounts of b12, folate. Finally, I re-read the study by Jill James on methylation issues in autistic kids, where she used folinic and TMG to correct/improve their methylation status -- I had never used TMG before. And since no adverse effects were reported in that group of kids, I figured I'd give it a good try. I did, and can tolerate them both very well. Night and day difference compared to 2011 and 2/3rds of 2012.