The question I always have is, if you take a supplement, does it survive the digestive system? And if it gets into the bloodstream in a satisfactory way, does it pass the blood-brain barrier and actually get into your brain where it can do some good? I’m unsure.
I would think that natural molecules, if needed, can cross the BB barrier. And sometimes man made molecules can cross when it shouldn't. That last one has to do with what I've read about Lipitor. The brain makes it's own cholesterol (all cells need some, and it doesn't cross the BB barrier), but Lipitor crosses the BB barrier, and wreaks havoc with the brains own cholesterol levels, and can cause problems, like transient amnesia, and or worse.