He was speaking in a spritual sense; you did not bother to finish out the chapter:
Mark 7
18 He asked them, “Are you so ignorant? Don’t you know that nothing that goes into a person from the outside can make him unclean?
19 Because it doesn’t go into his heart but into his stomach, and then into the sewer, thereby expelling all foods.”
20 Then he continued, “It’s what comes out of a person that makes a person unclean,
21 because it’s from within, from the human heart, that evil thoughts come, as well as sexual immorality, stealing, murder,
22 adultery, greed, wickedness, cheating, shameless lust, envy, slander, arrogance, and foolishness.
23 All these things come from inside and make a person unclean.”