I’ve heard several times that orange juice has an intensifying effect on a trip, making it stronger. I’ve never tried any psychadelic drug, so I have no personal experience in the matter, but it seems to be a common idea. I’m wondering if there is any objective evidence to support this idea, and if the cause is known.
It seems plausible to me that the expectation of its effects could explain them - a more experienced friend hands you some orange juice while you’re tripping and says that it’ll make the trip more intense. Since state of mind obviously has a great effect on a trip, this might be enough to trigger the sensation. The expectation built from this success, and maybe behavioral conditioning, may be enough to cause it to work later on. (Or even trigger a flashback - an acquaintance claims that she now has a flashback whenever she drinks orange juice.)
Is there any more to it than this? Is there some chemical or physiological reason to explain the effect of orange juice on a trip, or is it just a common belief that reinforces itself?
Here’s what I’ve heard (no reliability implied…)
LSD ‘uses’ Vitamin C in the body. Ingesting more, ie Orange Juice, intensifies the visual experience. Psychedelic Mushrooms do not use Vitamin C in this way, so adding C won’t have any effect.
Personally, I can offer no evidence that this is true. How do you measure such a thing? Try and figure out while tripping: gee, I wonder how much less I’d be messed up if I hadn’t had that glass of OJ…
There is no reasonable explanation for persistent urban legends about LSD and orange juice.
Maybe I just take the Sapir-Whorf hypothesis too seriously, but I suspect that the root of it comes from orange juice being acidic. “More acid” = “Stronger trip” because lysergic acid diethylamide and citric acid are basically equivalent, right? 
Of course, the same people who believe that sort of thing are liable to advise giving someone vitamin C tablets to bring them down from a bad trip, so go figure.
Either way, any subjective changes are entirely due to a spectacularly-enhanced placebo effect.
Now, let me tell you the one about my third cousin’s girlfriend’s friend who did too much acid and has spent the last twenty years in a mental hospital, convinced that he was a glass of orange juice. Or an orange. Or something.
IIRC there have been experiments about the ability of concentrated grapefruit juice to affect the pharmacokinetics of AIDS drugs. I think that it increases the uptake of certain drugs, effectively causing an overdose. Could be the same for orange juice.
boofy_bloke, grapefruit juice’s interaction with certain drugs is due to a component called bergomottin, which inhibits an enzyme that breaks the drugs down. Its effects are limited to a small, specific group of drugs, and would not extend an LSD trip.
Orange juice does not contain bergomottin.
Well there’s your problem. See this site.
That’ll be $150.