In the old testament, God told the jews they could not eat anything that crawls (bugs), but could eat hoof-footed animals that chew the cud (cows, lambs), but not to eat those hoofed animals that don't chew the cud (like pigs). Birds were ok to eat too...
But in the new testament, Jesus said that what you put in your mouth doesn't defile you (cause you to sin), so he basically said that what you eat won't make you a sinner. He said only that which comes out of your mouth defiles you (things you say).