I have read that NMDA agonists can reduce amphetamine tolerance.
Marvin Ross [http://www.schizophrenia.com/glycine.htm] says that,
"Post mortem evaluations of the brains of people with schizophrenia have shown that they have fewer NMDA receptors than people who do not have the disease. Both glycine and d-serine (NMDA agonists) have been found to be decreased in both the blood and cerebrospinal fluid of people with schizophrenia compared to controls. This has all led to the hypothesis that people with schizophrenia have too little NMDA and that is one cause of some of the symptoms of the disease – particularly the negative symptoms and the cognitive deficits."
If glycine is an NMDA agonist, then it should help amphetamine tolerace.
Gelatin was listed as the "food" highest in glycine.
Jello has gelatin, so I conclude that Jello can reduce amphetamine tolerance (and help with some symptoms of schizophrenia as well).
Is this a possibly valid conclusion?? Lots of Jello? hahaha


