What's the Book?

[slid_away]

I am not sure of the whole story line, all I know is that part of it is when humans get to a certain age, euthanasia is used and they are put back into the food chain.
I am sure it is set in the future.

[Quizmonster]

Soylent Green sounds a likely candidate.

[Sheherazade]

You might also be thinking of Logan's Run, wherein a crystal set in each person's palm changes color every few years, and starts blinking at 21, signalling time for cumpulsory euthanasia. The story concerns those who run away, seeking a place called Sanctuary.

However I don't recall that anyone gets eaten.

In Soylent Green, the dead are recycled into food wafers, but I don't think there was an age limit on living, though euthanasia was highly encouraged.And Soylent Green is the title of a film, which is only loosely based on a book called Make Room, Make Room.