For those interested, taken from imdb.
A tale of Earth in despair in 2022. Natural food like fruits, vegetables, and meat among others are now extinct. Earth is overpopulated and New York City has 40 million starving, poverty stricken people. The only way they survive is with water rations and eating a mysterious food called Soylent. A detective investigates the murder of the president of the Soylent company. The truth he uncovers is more disturbing than the Earth in turmoil when he learns the secret ingredient of Soylent Green.
The newest product is Soylent Green - a small green wafer which is advertised as being produced from "high-energy plankton". It is much more nutritious and palatable than the red and yellow varieties, but it is in short supply, which often leads to riots.
Thorn sneaks into the basement of the euthanasia facility, where he sees corpses being loaded onto waste disposal trucks. He secretly hitches a ride on one of the trucks, which drives to a heavily guarded waste disposal plant. Once inside the plant, Thorn sees how the corpses are processed into Soylent Green wafers. After Thorn escapes from the plant and heads for the supreme exchange with the information, he is ambushed by Fielding—who turns out to be part of the assassination conspiracy—and several other gunmen. In the shootout, Thorn kills some of the gunmen, but he is wounded, and retreats into a cathedral filled with homeless people. After a desperate fight, Thorn stabs and kills Fielding. When police backup arrives, the seriously wounded Thorn confides to Hatcher the horrible secret behind Soylent Green and urges him to spread the word.
"Soylent Green is people!"