God also prohibited the ingesting of blood ( Leviticus 17:11; cf. Leviticus 3:17; Leviticus 7:26-27; Leviticus 19:26; Genesis 9:4; Deuteronomy 12:15-16; Deuteronomy 12:23-24; Deuteronomy 15:23). From this law the Jews developed methods of draining or washing the blood out of meat that resulted in kosher (meaning fit or proper) meat. [1] The incidence of blood disease among livestock was much higher in ancient times than it is today. [2] Careful observance of this law would have resulted in healthier Israelites as well as obedient Israelites. [source][source][source]
Blood is the life-sustaining fluid of the body ( Leviticus 17:11; Leviticus 17:14). It is inherently necessary to maintain animal life, thus the close connection between blood and life. Life poured out in bloodshed made atonement for sin. Consequently the eating or drinking of blood was inappropriate since blood had expiatory value and represented life. [source][source][source]
"By refraining from eating flesh with blood in it, man is honoring life. To eat blood is to despise life. This idea emerges most clearly in Genesis 9:4 ff, where the sanctity of human life is associated with not eating blood. Thus one purpose of this law is the inculcation of respect for all life." [3][source]
The animals in view here seem to be those slain in hunting; they were not sacrificial animals ( Leviticus 17:13; cf. Deuteronomy 12:15). However the restriction about eating blood applied to all animals that the Israelites ate. Since God forbade eating blood before the Mosaic Law ( Genesis 9:4), which Christ terminated, people today should also refrain from eating it. What is in view is not simply eating "rare" meat (pink or red meat with a little blood in it) but larger quantities of blood either separately or as a kind of side dish. Eating raw, uncooked meat was also inappropriate. [source][source][source]