Someone on a B12 deficiency discussion group mentioned that he’d found that if he took folic acid (the synthetic version of the naturally-occurring folate) at the same time as methylfolate (a much more bioavailable supplement of folate; AKA Metafolin), he would start to get folate deficiency symptoms, even though he was supplementing it like a crazy person. I experimented myself and found the same thing — the folic acid cancels out the methylfolate. Folinic acid will do the same.
Because nothing can be easy.
I swear to you I found a PubMed article confirming that folic acid deactivates methylfolate if taken AT THE SAME TIME, but of course I lost it. But if you Google “folic acid blocks” you’ll find all sorts of discussions about it.
This is a separate issue from the problem some people have wherein folic acid will inactivate any folate in their bodies, as well as in all domestic pets within a five-block area, and wreak all kinds of deficiency havoc. We’re just talking supplement interactions here.
What’s annoying is that almost all vitamin B-complex preparations use folic acid, so if you’re taking those you have to schedule accordingly — 1.5 hours in between doses worked for me.
You might note that some experts feel that past a certain amount of supplementation (maybe 800 mcg), folic acid interferes with folate status in everyone to some extent. Here’s a description of why folic acid was marketed even thought it doesn’t work as well — it was patentable, whereas naturally-occurring folate isn’t.