Hi, Johnners, and Pettals, I'll certainly tell you what I did but just please remember that I am not a doctor, I was just one desperate person whose GP did a blood test for B12 then phoned, said I was "marginally low" at 167ng/L (180-900) but I trusted him and thought "marginally low" was OK. I went on to develop 28 symptoms which only elicited GP's contempt for having kept a diary of what was going on.
Bear in mind that if you start on sublingual B12 that this will raise the B12 level and will therefore distort the results of subsequent B12 tests, to start will be your own choice. I had no option, nobody would listen, contempt and anger were showered on me. Dreadful.
I bought sublingual methylcobalamin, 5mg (5000 mcg) tablets, 60 per bottle, from Amazon. Another highly recommemded make is Jarrows, which has given many people success. Must be methylcobalamin, no other form, do not buy cyanocobalamin as this will not repair nerve damage which my symptoms indicated was already happening. I also bought methylcobalamin in spray form, delivers 500mcg per sprayPure Vegan B12.
The principles of the absorption of B12 by either sublingual or oral means, both different, are explained in Kevin Byrne's dissertation entitled "The Enterohepatic Circulation of Vitamin B12" available from the Downloads section of the Pernicious Anaemia site. Too long to explain, but basically he favours sublingual over oral. Sublingual: melt very slowly under tongue where there are membranes which absorb B12 and so avoid the intestinal route; oral, swallow with food.
My regime was to take 5 tablets spread out through the day, making a total of 25000mcg, or 25mg, per day, very carefully sublingually, do not crunch up! Does not work like that. Plus a couple of the 500mcg sprays daily. Sometimes I took 6 tablets a day, being rather desperate as the synptoms had rapidly being getting worse before I began this regime.
By the end of five weeks the symptoms had distinctly lessened and where before I had had to get up during the night and stamp around to try to mitigate the strong tingling and pains in feet, up legs, etc., I could bear the lessened tingling/pains better. By the end of four months of intense B12 therapy as described, all symptoms had gone, my twitching face muscles were the last to settle. My B12 level was above 1500, expressed as >1500. I now keep my level at around 1200-1300, and feel fine, normally energetic and pain free. Self finance blood testing at myrios.co.uk. but do check out Thyroid UK labs or others.
Kept up the regime for another 6 weeks just to make sure every symptom was gone, then I stopped taking the subl B12 but meantime concentrated on dietary means, with one Betaine Hydrochloride with Pepsin with main meal to increase strength of stomach acid in case that would help, threw out microwave as microwaving destroys B12, and learned of food sources of B12 -sardines, chicken livers (v high) liver (bumps up the folate levels - good) dairy products in all forms, red meat; sea fish..
I have had no supplementary sub-l B12 since April 2012 but monitored levels are still high, !000pmol/L (141 -489), divide pmol/Lresult by 0.738 which is the conversion factor, and this gives last level at 1355 ng/L (191 - 662). I would supplement at 2500mcg (splitting a 5000mcg tablet, twice daily sublingually as I/net studies indicate that should be enough, but remeber, I am no doctor.
This has worked for me but remember I did not have the usual tests for Pernicious Anaemia, just laughed at, but I found 6 months later that on the test giving 167 as my serum B12 level the lab had advised GP he should run tests for Intrinsic Factor and Parietal cell antibodies.
Trust nobody, always get copies of all blood test.
Hope this helps