It now appears that there is a new twist on both paradoxical folate deficiency and Metafolin. There are other people, like myself who go into folate deficiency symptoms on small doses of Metafolin, after a little while. This may be more pronounced with mb12 but may not be. The first place I recall seeing it was with people taking Hycbl and small amounts of folinic acid and small amounts of Metafolin. My experience and of some others and not of others, is that when we increase the amount of Metafolin to around the dose sizes of Deplin, 7.5mg to 15mg, that this donut hole of paradeoxical folate deficiency goes away. So perhpas the explanation goes something like this. The Metafolin gets the methylation going. It is, at each level an on or off binary situation. When it turns on a small amount of Metafolin is not enough to sustain it and a person starts getting their characteristic low folate symptoms. As this has been well demonstrated with hycbl and and the SMP, and those doing the ABP also have the same effect. A low dose of Metafolin, gradually increased causes all sorts of problems in susceptable people, paradoxical folate deficiency symptoms. It takes around 7.5mg or more of Metafolin to overcome that and have an unblocked methylation without folagte deficiency symptoms. The company doing Deplin got it right.