Prisoners using NOODLES as currency instead of traditional cigarettes

American prisoners are using packets of ramen noodles as currency instead of traditional cigarettes, researchers have discovered.

The "underground economy" of jails used to be fuelled with tobacco, which was used in place of real cash.

But academics from the University of Arizona's School of Sociology said lags were now enduring harsh conditions which meant food was more valuable than cigarettes.

Researcher Michael Gibson-Light said: "The form of money is not something that changes often or easily, even in the prison underground economy; it takes a major issue or shock to initiate such a change.

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

The academics found prisoners often face "punitive frugality" which means they are forced to depend on family or friends to provide decent food.

"Punitive frugality is not a formal prison policy, but rather an observable trend in prison administration practice in institutions throughout the country," Gibson-Light added.

"Throughout the nation, we can observe prison cost-cutting and cost-shifting as well as changes in the informal economic practices of inmates.

"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."