The US Congress on Friday allowed an estimated $5 billion cut to a federal food stamps program to take effect, slashing the social safety net for the poor, elderly and disabled.

Almost 48 million, or one in seven, Americans have had food subsidies cut 13.6 percent after a 2009 recession-fighting measure expired Thursday with no congressional action to extend it.

The cuts come as the world's largest economy has still only achieved a tepid recovery from severe recession, marred by persistently high unemployment and budget gridlock in Washington.

The cutbacks increase the challenges for Americans struggling to buy food amid a sharply widening income gap between the rich and the poor.

And supermarkets and grocery stores were expected to feel the pinch as consumers counted pennies to make the newly stretched ends meet.

A household of four will see $36 less a month in benefits, as a maximum $668 allotment is cut to $632, according to the US Department of Agriculture, which runs the program.

The government had boosted the Supplemental Nutrition Assistance Program benefits temporarily in 2009 to help the most vulnerable weather the worst US economic crisis since the 1930s.

But the extra SNAP benefits enshrined in the American Recovery and Reinvestment Act fell by the wayside this week as a bitterly divided Congress resumed budget negotiations.

SNAP is a major part of the five-year Farm Bill, which the Senate and the House of Representatives began negotiating on Wednesday.

The Republican-controlled House has been pushing for sharp cutbacks in SNAP spending as part of a budget strategy to reduce the US deficit, while Democrats are seeking smaller cuts.

Republican Representative Tim Huelskamp of Kansas, a big farm state, said the SNAP program was bloated.

"Eighty percent of the farm bill is now made up of food stamp spending -- which has nearly tripled in the last twelve years," he argued.

"The remaining twenty percent is dedicated to traditional farm, conservation, education and other programs. It is absolutely critical that we target and transform food stamps to those in need -- and put the others back to work."

"For American families, SNAP provides a lifeline when they face an economic disaster," said Democratic Senator Debbie Stabenow, chair of the Senate's agriculture committee, according to prepared remarks for the opening of the Senate-House negotiations meeting.

"For those getting food help, that means every child, every senior citizen, every disabled veteran, every person who's lost their job will have a more difficult time putting food on their tables."

House Democrats took to Twitter to protest the SNAP cuts and the impact on the economy.

"Food stamp cuts today hit families hard, including 900,000 veterans. And GOP wants to slash even more," wrote Representative Chellie Pingree of Maine.

Representative Henry Cuellar of Texas tweeted: "SNAP cuts on Friday leave 48 million Americans with $16 billion less to spend over three years."

As of July, 47.6 million people were in the SNAP , an increase of 1.7 percent from a year ago, and monthly benefits rose 0.4 percent to $6.3 billion, USDA data figures showed.

The Congressional Budget Office, the nonpartisan agency for Congress, has said the SNAP program had grown significantly between 2007 and 2012, "largely related to the severe recession and slow recovery."

The number of people receiving SNAP benefits jumped from about 26 million to 47 million, and annual spending more than doubled from $35 billion to $80 billion, the CBO said.

The center on Budget and Policy Priorities noted that Friday's SNAP cuts mean benefits will average less than $1.40 per person per meal.

"This is a serious cut, especially considering that over 80 percent of SNAP participants live in poverty. House and Senate members who are now beginning to negotiate a final Farm Bill should keep this benefit cut in mind as they consider, in reauthorizing the SNAP program, whether to make even deeper cuts," the think tank said.