A man reading the allocation requirements of soylent
Soylent was a type of ration given to the population of Sanctuary Districts during the 21st century.
In 2024, according to a couple of posters, the allocation requirements for the rationing of soylent changed for the Blue Zone in Sanctuary District A, unlike the Red Zone, which did not. (DS9: "Past Tense, Part I")
Soylent was a type of food introduced in the science fiction novel Make Room! Make Room! (1966). The 1973 film Soylent Green was based on that novel. A real food named after it exists today, possibly explaining its use in the districts.