Hi
@Sparrowhawk Low folate for me is strongly epithelial - I have a tiny 'paper-cut' on my skin for the past three years that appears (quite sore, just like a paper-cut) when folate goes low, then since the Freddd protocol, almost magically disappears within hours, or less, when I ingest enough folate. When I first began to notice it three years ago I hadn't a clue what it was, but now it's a useful signal for me - though I haven't had it now for several weeks, which is a good sign. I also get peeling lips. The other epithelial issue is the irritation of the gut lining - low folate causes a lot of peristalsis, then running to the loo, 4 or 5 times a day. All reverts to completely normal within hours (or less) and stays normal when enough folate. Then there's the hair follicle irritation - brief bouts of crazy itchy scalp, followed hours later by lots of hair-shedding. I am very happy this has stopped with enough folate!
Potassium: muscle aches with total weakness (can barely walk around & sometimes can't raise my arms or sit up in bed, or wash my hair - this was before I realised what it was), pulsatile tinnitus (whoosh noise that matches my pulse) which means my blood pressure is going high. Tingling feet, if left without taking potassium, progresses to general tingling, even around mouth and face, also aching jaw and gum on left side, then breathlessness, banging heart - this gets scary, but now I know more what I'm doing it doesn't happen. Agitation and irritability comes with low potassium too. Oh, by the way, I made the mistake of taking relatively high-dose b2 (35mg) along with high folate recently and that very quickly brought on the attack I just described - breathless, numb face, banging heart, before I realised it was the b2 along with high folate using up potassium. Horrible.
When my hypothyroidism was bad the low potassium was worse - hypothyroidism causes low potassium too so it's always been a struggle. The b2, so far, is helping my thyroid & adrenals a lot (it's raising my low iron that had got seriously low on the Freddd protocol, because of keeping the b2 low). I get by on much less folate (and a bit less potassium) now - am just hoping this continues.
I learned to identify signs by reading endlessly here, and from years of myriad symptoms that gradually vanished with the introduction of the Freddd protocol