Hoping to summon @Freddd for help here, I'm getting to the point where I'm totally stuck. For about 4 months, I was on 6mg mFolate. Seemed to be working well. I tried going down to 2mg, and then 1mg. Noticed I had more energy and was much less irritable. Great! So I stuck to 1mg, and slowly started getting more tired, and a little depressed. Guess my stores ran out. Went back up again, this time to 5mg. TONS of energy - it felt pretty unnatural, and more like I was on stimulants. Except I started getting super irritable again, and the energy tapered off after about 2-3 days, leaving me feeling a little depressed, irritable, and lethargic. On day 4, I said "to hell with it" and tried 10mg. Once again, TONS of energy, more than I could handle. And WAY too irritable and anxious. Very overwhelming. Took some niacin and felt much better. Went back up to 3mg a few days later, hoping to find a sweet spot. Great energy day 1, more energy day 2 (borderline too much), started getting irritable again. Day 3 (today), less energy and still slightly irritable (even after potassium). Actually about to take some niacin again I think. Edit: the niacin helped, feeling much calmer and less irritable after about 30-40 minutes. Contrary to what I previously believed, it sounds like: More mFolate (3mg+) = more irritable as dose increases, more energy (but short lived, wears off leading to irritability, depression, lethargy), and oddly enough more apathetic Less mFolate (2mg) = not abnormally irritable, no huge boost in energy, motivated Even less mFolate (1mg) = starting to get depressed and less motivated I've tried potassium over and over and any benefit is borderline placebo for me. A recent blood test put me at 4.3 mmol/L while on 1mg mFolate and no potassium supplementation. It did show that I'm low on zinc & copper (with a poor ratio too), which I'm planning to address next. My homocysteine, B12, magnesium, D3, and everything else were all within range. My theory is that too much mFolate just overdrives everything, makes me irritable and over energized, and then my body adapts to the energy level, but the irritability remains. But I want to rule out anything else. Obviously increasing the mFolate from 5mg to 10mg didn't decrease the symptoms, so I don't think it's paradoxical folate deficiency. Should I just tone it back until the irritability subsides, and then accept that I can't feel THAT energetic all the time?