What was the reason for having clean and unclean animals ie. Leviticus 11 and Deuteronomy 14:3-21? Has this been done away with or is it still in force? And was it just for religious reasons or were there health implications/benefits also?
The Jewish dietary restrictions were primarily for health reasons, but the Lord ordained that only certain of the clean animals were suitable for sacrifice. At the springs of Elim, Hi demonstrated the benefit of following His way. After turning the bitter water sweet, He issued “a decree and a law.” He said, “If you listen carefully to the voice of the LORD your God and do what is right in his eyes, if you pay attention to his commands and keep all his decrees, I will not bring on you any of the diseases I brought on the Egyptians, for I am the LORD, who heals you.” (Exodus 15:26)
The unclean animals were often very difficult to prepare in such a way as to make them free from parasites or harmful bacteria. This is why when Daniel refused food from the King’s table, eating only vegetables and water, he became healthier looking than his Babylonian counterparts (Daniel 1:12-17), and why the average Jew lived three times as long as the average Egyptian.
In Mark 7:18-20, Jesus declared all foods clean. This was confirmed in Acts 10:9-15. But even so, it’s been demonstrated to this day that following these dietary restriction makes people healthier. A great book on the subject is “None Of These Diseases” by Dr. S. I. McMillen.