Watchtower, November 15, 1967, page 702, Question from Readers
Humans were allowed by God to eat animal flesh and to sustain their human lives by taking the lives of animals, though they were not permitted to eat blood. Did this include eating human flesh, sustaining one’s life by means of the body or part of the body of another human, alive or dead? No! That would be
cannibalism, a practice abhorrent to all civilized people. Jehovah clearly made a distinction between the lives of animals and the lives of humans, mankind being created in God’s image, with his qualities. (Gen. 1:27) This distinction is evident in His next words. God proceeded to show that man’s life is sacred and is not to be taken at will, as may be done with the animals to be used for food. To show disrespect for the sanctity of human life would make one liable to have his own life taken.—Gen. 9:5, 6.
When there is a diseased or defective organ, the usual way health is restored is by taking in nutrients. The body uses the food eaten to repair or heal the organ, gradually replacing the cells. When men of science conclude that this normal process will no longer work and they suggest removing the organ and replacing it directly with an organ from another human, this is simply a shortcut. Those who submit to such operations are thus living off the flesh of another human. That is cannibalistic. However, in allowing man to eat animal flesh Jehovah God did not grant permission for humans to try to perpetuate their lives by cannibalistically taking into their bodies human flesh, whether chewed or in the form of whole organs or body parts taken from others.