A while back, I received an email from a cat lover asking, “Do kitties know not to eat what is bad for them? Is there any good logic in the statement that, if they eat something, it is probably OK for them?”
I get questions like this all the time, and the answer is NO!
I wish cats DID have this knowledge, but cats (like small children) don't always know what is best for them. It's up to you to keep them safe.
Kids can be attracted to many poisons and toxins. So can cats. In fact, toxins such as antifreeze are slightly sweet tasting and some cats like the taste. This is so dangerous because as little as one teaspoon of antifreeze can be fatal to a cat!
Cats will also ingest “nonfood” items that their bodies simply cannot digest. This can also be fatal. Many “foreign bodies” must be surgically removed from cats' stomachs and intestines to save their lives. Common items that cats should never eat are string, yarn, shoelaces and toys.
An article that might be helpful is Gastrointestinal Foreign Bodies.
Another good article is Dangerous Human Foods.
Please keep your cat safe. Don't feed your cat anything unless your veterinarian recommends it. Supervise your cat's playtime to ensure he does not ingest any foreign materials. And carefully store all poisons and toxins out of your cat's reach.