Apple seeds and cherry pits are poisonous—in theory

Apple seeds and cherry pits, commonly thought to contain high levels of vitamin-C actually contain no health benefits at all.  They contain cyanide, which when consumed in large quantities can result in mild poisoning symptoms.  Symptoms of mild poisoning include headache, dizziness, confusion, anxiety, and vomiting.  One or two seeds won't hurt you, but larger doses can lead to difficulty breathing, increased blood pressure and heart rate, and kidney failure.  Reactions can include coma, convulsions, and death from respiratory arrest.  Chewing the seeds makes their toxicity even higher and more than a handful's worth can cause the symptoms of poisoning to occur.  So, next time you feel like swallowing a cherry pit because the garbage can is too far away...maybe you should think again. 

Sources:
http://chemistry.about.com/b/2007/09/12/yes-apple-seeds-and-cherry-pits-are-poisonous.htm