Galatians 2:7-9... So, since Paul was sent to the gentiles, the gentiles must have had food laws, etc., against which he was preaching.
But Peter was sent to the circumcision, as were all the Galilean Apostles... and so, these words apply:
Esaias 66:1 Thus saith the Lord, Heaven is My throne, and the earth is My footstool: what kind of a house will ye build Me? and of what kind is to be the place of My rest? 2 For all these things are Mine, saith the Lord: and to whom will I have respect, but to the humble and meek, and the man that trembles at My words? 3 But the transgressor that sacrifices a calf to Me, is as he that kills a dog; and he that offers fine flour, as one that offers swine’s blood; he that gives frankincense for a memorial, is as a blasphemer. Yet they have chosen their own ways, and their soul has delighted in their abominations. 4 I also will choose their mockeries, and will recompense their sins upon them; because I called them, and they did not hearken to Me; I spoke, and they heard not: and they did evil before Me, and chose the things wherein I delighted not. ... 17 They that sanctify themselves and purify themselves in the gardens, and eat swine’s flesh in the porches, and the abominations, and the mouse, shall be consumed together, saith the Lord.
Matthew 15:12 Then came His disciples, and said unto Him, Knowest thou that the Pharisees were offended, after they heard this saying? 13 But He answered and said, Every plant, which My heavenly Father hath not planted, shall be rooted up. 14 Let them alone: they be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch. 15 Then answered Peter and said unto Him, Declare unto us this parable. 16 And Jesus said, Are ye also yet without understanding? 17 Do not ye yet understand, that whatsoever entereth in at the mouth goeth into the belly, and is cast out into the draught? 18 But those things which proceed out of the mouth come forth from the heart; and they defile the man. 19 For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies: 20 These are [the things] which defile a man: but to eat with unwashen hands defileth not a man.
In other words, dirty hands don't defile a man, but unclean thoughts do. Because food doesn't just pass harmlessly through the body... but apparently dirt does.