Dr Ben Lynch

Folic acid doesn't just fail to help your brain. It actively blocks the door. Folate receptor alpha is the primary transport into your brain for methylfolate. It's selective — it's supposed to let in the active form your neurons actually use. But folic acid binds to that receptor tightly. And it doesn't let go. So even if you're taking methylfolate, even if your diet looks clean — if folic acid is occupying that receptor, methylfolate can't get through. Your brain runs on this nutrient. Neurotransmitter production, myelin repair, DNA synthesis — none of it works without it. This isn't a minor inefficiency. This is a locked door.