The Clean and the Unclean Foods

The distinction between clean and unclean foods emphases the divine calling of Israel to be a holy nation, different from the other nations of the earth.
The clean animals symbolises Israel;
The unclean animals symbolises non-Israelites.
Blood is the symbol of life - the prohibition of eating blood indicate that all life is sacred.

The food regulations summarised.

(Lev 11:1-47; Deut 14:3-20)
The regulations defining clean and unclean animals are divided into three sections, which correspond with their three main regions of habitation:
1. Land (Lev 11:1-8);
2. Sea (Lev 11:9-12);
3. Air (Lev 11:13-23).
1. The land:
Only cloven-hoofed, cud-chewing land animals are clean, all other mammals are unclean.
2. The sea
Only fish with fins and scales are clean; all other fish are unclean.
3. Air
Birds of prey and flying insects that walk rather than hop are unclean; all other birds and insects are clean.

The function of these regulations

The clean and unclean animals parallel clean and unclean people (Israelites and non-Israelites).
Within the category of clean animals, there are sacrificial and non-sacrificial animals (within Israel there are priests and laity).
Lev 20:24-26 is behind those regulations.
The food regulations made it difficult for an Israelite to participate in meals provided by non-Israelite.
Thus, it limited contact of Israelites with other people.

The rationale behind it

No clear found yet.
But, a common factor among many of the unclean animals is that they depend on the death of other creatures in order to survive.
Most of those unclean animals eat meat (birds of the prey for example - Lev 11:13-19).

The blood prohibition

Lev 17:1-16 - Deut 12:16, 23-25.
Gen 1:29 - humans and all other creatures are vegetarians;
Gen 9:4 - God prohibits to eat meat with blood.
Even in killing the animals, Israelites should differ from other nations.

New Testament connections

Mt 15:1-20, Mk 7:1-23 (Mt 15:11; Mk 7:15) - all foods clean;
Acts 10:1-11:18 - no people are impure or unclean (Acts 10:28).
Thus, God no longer distinguish between “clean” Jews and “unclean” Gentiles.
With Jesus’ death and resurrection, both the Jews and the Gentiles are recipients of God’s grace and mercy (Acts 15:7-9).
Thus, food regulations like sacrifices no longer have any purpose.

How about blood?

So commentators think it is still valid based on Acts 15:20,29. Since the covenant from Gen 9:4-6 that introduced it is still valid.
But, it is interesting to notice then that Jesus commands his disciple to “drink his blood” (Jn 6:53-56).