I think the donut hole was that there was enough methylfolate to start the healing (thus the need for potassium) but not enough for maintaining it. Ergo: one has to give lots of methylfolate (then the hole closes). But one can not give lots of methylfolate when there's not enough mB12, because then the methylfolate will flush out of the cells, giving methylfolate deficiency symptoms. One needs to increase the mB12. When you do not give enough mB12, you'll see b12 deficiency symptoms. As soon as all the mB12 is used up you get again methylfolate to flush out of the cells and you'll see the methylfolate deficiency symptoms again. So I'd say yes, you have to (try to) balance them and raise them both if you don't want to get trapped in a donut Well, at least that's how I perceived it.