Please review the section on Mathew 15:11 as it is a parallel account.

The discussion doesn’t go into what foods are permissible to eat. Rather some of Jesus’ disciples were violating a tradition of the elders by eating with unwashed hands.

“Now when the Pharisees gathered to him, with some of the scribes who had come from Jerusalem, they saw that some of his disciples ate with hands that were defiled, that is, unwashed. (For the Pharisees and all the Jews do not eat unless they wash their hands, holding to the tradition of the elders, and when they come from the marketplace, they do not eat unless they wash. And there are many other traditions that they observe, such as the washing of cups and pots and copper vessels and dining couches.) And the Pharisees and the scribes asked him, “Why do your disciples not walk according to the tradition of the elders, but eat with defiled hands?” And he said to them, “Well did Isaiah prophesy of you hypocrites, as it is written, “‘This people honors me with their lips, but their heart is far from me; in vain do they worship me, teaching as doctrines the commandments of men.’ You leave the commandment of God and hold to the tradition of men.” And he said to them, “You have a fine way of rejecting the commandment of God in order to establish your tradition!” (Mark 7:1-9)

Verse 15 is in response to the Pharisees accusation about eating with unwashed hands.

Mark’s account concludes with Jesus explaining the parable to his disciples in private.

“For from within, out of the heart of man, come evil thoughts, sexual immorality, theft, murder, adultery, coveting, wickedness, deceit, sensuality, envy, slander, pride, foolishness. All these evil things come from within, and they defile a person.” (Mark 7:21-23)