"And [Jesus] said to them, “Then are you also without understanding? Do you not see that whatever goes into a person from outside cannot defile him, since it enters not his heart but his stomach, and is expelled?” Thus he declared all foods clean." Mark 7:18-19 (ESV)
But of course all foods are not clean. There really are things you shouldn't eat.
And there's this: "Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfill. For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled." Matthew 5:17-18
Did he destroy the law, or didn't he? See how it works? People believe what they want, and they come up with scriptural justifications for it either way.