When it comes to the underground economy in prisons across the United States, Ramen noodles have surpassed cigarettes as the most popular currency, according to a new study released Monday.

The report by Michael Gibson-Light, a doctoral candidate at the University of Arizona’s school of sociology, found the rise in the popularity of Ramen was due to the decline in the quality and quantity of food in prisons.

“Prisoners are so unhappy with the quality and quantity of prison food that they receive that they have begun relying on Ramen noodles — a cheap, durable food product — as a form of money in the underground economy,” Gibson-Light said in a statement. “Because it is cheap, tasty, and rich in calories, Ramen has become so valuable that it is used to exchange for other goods.” Tweet This

READ MORE: U.S. to stop using privately-operated prisons due to safety concerns

Instant noodles were seen as more valuable than clothing, hygiene products, and even services, such as laundry and bunk cleaning, according to the report. Ramen was even used in poker games or gambling on football pools.

Story continues below advertisement

Gibson-Light interviewed nearly 60 inmates and prison staff members from May 2015 to May 2016 at a prison in the southern United States. The prison was not identified to protect the confidentiality of prison inmates.

He looked at monetary exchanges among inmates, and how they were responded to a decline in services. The study found that spending on corrections has not kept pace with the number of inmates in prisons since 1982.

READ MORE: How gun violence in America, Canada and the world compares

Gibson-Light calls the rise in the popularity of Ramen the “punitive frugality” effect.

“Throughout the nation, we can observe prison cost-cutting and cost-shifting as well as changes in the informal economic practices of inmates,” he said, in a statement. “Services are cut back and many costs are passed on to inmates in an effort to respond to calls to remain both tough on crime and cost effective.” Tweet This

The study also found there has been a shift towards foods like Ramen even at prisons where tobacco has been banned.

[graphiq id=”eQRRwJCL0m9″ title=”Total Adult Incarcerated Population in the United States” width=”600″ height=”494″ url=” https://w.graphiq.com/w/eQRRwJCL0m9″ ; link=” https://www.graphiq.com/vlp/eQRRwJCL0m9″ ; link_text=”Total Adult Incarcerated Population in the United States | Graphiq” ]

Story continues below advertisement

Gibson-Light will present his research at the 111th Annual Meeting of the American Sociological Association (ASA) and says while the study is small he called for a longer study on what a decline in prison food services could mean for the quality of care for those behind bars.

“The use of cigarettes as money in U.S. prisons happened in American Civil War military prisons and likely far earlier,” he said. “The fact that this practice has suddenly changed has potentially serious implications.”