My high serum B12 seems to indicate impairment in my body's ability to absorb nutrients. For those of you with lab reports, have you found that your B12 is also high (after beginning supplements). I only take 1 mg a day of sublingual methylB12. So.....my latest topic of research is cellular permeability. I want bad things to go out and the good things to go in! I know that phospholipids are key, but I also want to know how impaired methylation and sulfation affect this process. The fact that I am on a "methyl budget" may be important as well.