If you must eat plants and can't watch the animals then:<p>Spread a bit on your skin,  wait a while to see if there's a rash.  Touch some to your lips and tongue, again waiting a while to see if there's a reaction.  Eat a tiny bit, wait a while.  Eat a larger bit and then wait.  Continue upping the dose.<p>This is from memory from the SAS survival guide.  Should take days and isn't very safe but may be the best you've got.