"After a month of watching what I am eating/drinking during the day I have found a few sources of intake that definitely inhibit going into hyperspace... For me at least:
Red Bull- Kills any visuals. I can have a single 8oz can during the day and it will stop a visual tip from coming on. I still go out into space a bit, but the visuals don't happen.
Ginkgo Biloba and Ginseng - Blocks a trip completely.(for me) Sometimes causing feedback. (noise, rapid pulses of sound, etc.) I'm not sure yet if its just the Ginko Biloba or the combo as I usually ingest them together.
Caffeine (via coffee) - Thank the lord is relativity ok. Excessive amounts (6 to 10 cups, yes I do that... ) seems to lessen the experience but nothing definitive.
Alcohol - Destroys the experience into more of a third person, "I'm watching a film" frame of mind. At higher inebriation, (when you would normally call yourself 'drunk'
massive amounts of feedback, audio and visual noise destroy any experience, as if receptors are blocked and everything bouces back which is quite unpleasant.
Salt - had possible detrimental effects but nothing conclusive. Consumed a salt beagle in the morning, a large salty b.l.t. in the afternoon.
Fats - Make me feel bloated. Other than that, no real side effects.
So seems like"
https://www.dmt-nexus.me/forum/default.aspx?g=posts&t=32183