Thanks en bloc - I'll try anything now and will order more chewables as advised. It didnt make any difference last time but perhaps I need to chew more than one a day. I do know it's impossible to take too much. I also took a lot of folic acid for two years to address Methotrexate side effects as a folic antagonist - so I paid for private tests (can't recall what they were called Hemostecene and M something?) 18 months ago in case the folic had skewed the serum B12 results. I have these somewhere too so will look at Mrs D's B12 threads and go back to the B12 possibility again.