I had heard that folic acid can block methylfolate, but when I started taking methylfolate I had a strong reaction to it even though I was taking at least 1000 mcg of folic acid so I assumed that for myself folic acid wasn't a problem. But then I read about The Methyl Trap and DHFR. Correct me if I'm wrong, but if you take folic acid in high doses then it slows or blocks DHFR which converts folic acid into methylfolate and folinic acid. If this happened to me then I would have been depleted of methylfolate. If I was depleted of methylfolate when I started taking methylfolate could that be part of the reason I reacted so strongly to it?