I only know what I said in that post of mine you quoted. That Freddd and dbkita reported that both potassium and vitamin C blocked/reduced methylfolate absorption for them. dbkita also said that his mom was taking vitamin C with methylfolate and when he told her about the blocking effect she tried taking them apart and ran into some trouble. Xara also said that she heard that iron could block methylfolate. She said she thinks she heard it from Freddd. Vitamin C actually increases absorption of iron though.