As long ago as “The Jetsons” in 1962, TV shows and movies have depicted humans ditching meals for nutrition pills. In “Soylent Green,” it’s a switch we make out of necessity: Overconsumption has caused fresh produce to become scarce. A head of lettuce, two tomatoes and a leek retail for $279, and a sliver of beef is the ultimate luxury.

The general public is forced to live off products from the Soylent corporation, whose wares contain “high-energy vegetable concentrate” — and are dismissed by one elderly customer as “tasteless, odorless crud.” Its latest artificial meal is Soylent Green, a “miracle food of high-energy plankton gathered from the oceans of the world.” It proves popular enough to be rationed to a single day of sale per week, but as Thorn discovers, it’s not what it seems to be. (We won’t spoil the ending, though if you know anything about the film, it’s probably the horrifying revelation about Soylent Green.)

“Soylent Green” opens with photographs showing how modern Americans evolved from frock-coated settlers to fishermen, farmers and early town-dwellers. The slide show then blurs into a rush of cities with heaving sidewalks, smog-cloaked traffic jams and even Tokyo-style “professional pushers” cramming commuters onto subway trains. A title card tells us the population of New York City is 40 million; an exasperated Thorn at one point remarks, “There are 2 million guys out of work in Manhattan alone — just waiting for my job!”

Perhaps influenced by the 1972 heat wave in the Northeast and the first oil crisis of the early 1970s, “Soylent Green” imagines a sweltering future where the temperature never dips below 90. Margarine spoils in the fridge, and a sickly fog, similar to London’s historical “pea-soupers,” hangs in the air, forcing the city’s last remaining trees to be shielded under a tent. Whether these calamities are the fault of humankind or a natural disaster isn’t made clear, but in the source novel, it’s implied to be the former.

One scene shows widows collecting “death benefits,” implying that your family will be rewarded if you opt out. It’s a moment that catches the eye of Sol Roth (Edward G. Robinson), who attends a clinic where he’s welcomed by a glamorous assistant. He’s asked to choose his favorite color and soundtrack, takes a mouthful of medicine and is placed in bed while an orderly pushes two buttons on a console. A wall-sized TV then plays a montage of pacifying imagery (grazing stag, golden dawns, rivers) as the character exchanges a tender “I love you” with Thorn. (Robinson himself would die 12 days after shooting wrapped.)

A controversial subject at the time, assisted dying is legal today in Canada, Colombia, Australia and parts of Europe. In 2018, 142 people traveled from Germany, France and Britain to Switzerland’s Dignitas facility to make use of the country’s physician-assisted suicide policy that does not set a minimum age, diagnosis requirement or qualifying symptoms.