Apple seeds

The other day we had an im go unresponsive in the showers.
He was sent out to local hospital, we were suspecting he had
been cheeking some of his meds and had taken a lot at once
to avoid being caught when our team went through to do a
drug search. As it turns out 2 days later after returning from
hospital he confessed that another im had told him he could get
high if he ate a bunch of apple seeds. Well he saved up about a
1/2 cup worth and ate them. I was not aware of the
equivelance to cyanide. Has anyone else come across this at
their jail? Any other fruits to be wary of?