This could be a placebo or it could actually be true, I don't know, I can say when I eat a mango, I do notice a change in the buzz I feel, not an increase in intensity, but just a change in the stone I get.. could be the sugar in the mango, but its a more active alert high, not so much a dopey couch lock
I don't think its the sort of thing we will get scientific tests on.. and it will remain a matter of opinion based on experience's had, but hell if I can eat a tasty mango and have it change the way I get high.. bonus!