Food pantries across the Archdiocese of Boston are witnessing the basic principles of economics this Thanksgiving.

The national recession has placed upon such charitable organizations an increased demand for assistance. The supply though, which in some cases has remained stagnant and in others, has seen an infusion of food and other goods, cannot seem to keep pace with the burgeoning demand.

“All of our volunteers working in the local parishes have seen an increase -- people they have never seen before coming to get assistance with heat, utility payments, fuel assistance, or food vouchers to local grocery stores,” said Paul McNeil, the executive director of the Society of St. Vincent de Paul in the Archdiocese of Boston. “You can see more people asking for help than in the past.”

Tiziana Dearing, the president of Catholic Charities for the Archdiocese of Boston, said her organization is facing a similar situation.

“The economy has definitely made things tough on people,” said.

Dearing said that Catholic Charities has seen an increase in needs requests of 20 percent this quarter, compared to this time in the last fiscal year. So far, Dearing has witnessed a spike of 34-percent in requests for mortgage assistance and 14 to 15-percent in utilities and food assistance.

“It’s not even a complete quarter to compare apples to apples,” she said.

Bill Pye, the executive director of the food pantry at Sacred Heart Parish in Middleborough and president of the St. Vincent de Paul Society there, said his pantry has seen similar trends.

Last year, he said the parish pantry gave 180 families a Thanksgiving food basket, and averaged a monthly client load of 287. This year, it is giving 235 baskets and has an average monthly client load of 305, according to his current estimation.

St. Vincent de Paul gives the same number of Thanksgiving food baskets every year.

“It’s what we decided we could financially afford,” McNeil said. “The cost of groceries goes up every year. Could we do more? Absolutely. But, we set our number at 4,500.”

The baskets include turkey and all the fixings for a family of four, throughout the archdiocese. Proceeds from their thrift stores are used to purchase food for the baskets.

Dearing said that Catholic Charities has received 4,000 requests for food, up from last year. The bulk of those came from the greater Boston area but 900 requests came from the Brockton area, and 450 requests came from the Lowell area.

“We could do more, but we have a supply issue,” Dearing said.

“That’s a lot,” she added. “Demand is up. People started requesting early.”

About three weeks ago, the Catholic Charities Central food pantry ran out of food and this October in Dorchester, the organization gave out 11,000 pounds of food over four days, compared to 4,000 pounds at the same time in 2006, Dearing said.

“There’s never enough, especially at our smaller locations,” she said.

This year, more families have requested necessities other than food since food stamps cannot be used for items like cleaning products, she said.

“They need more -- a broader scope of the basics than they have in years past,” Dearing said.

Though the picture may seem grim, there are bright spots, however.

People throughout the archdiocese have hosted brown bag parties to raise food for Catholic Charities.

Pye said that Sacred Heart’s pantry is supported by food donations, as well as fundraisers like a golf tournament and a wine tasting. He is expanding fundraising operations to include grants.

Despite the challenging economy, he estimates more people are donating to the pantry and volunteerism is up there.

“They’re all in the giving mood,” he said. “We’ve got volunteers coming out of our ears.”

“Without all our volunteers and the Greater Boston Food Bank, we’d have to close,” Pye added.

McNeil estimates that St. Vincent de Paul will distribute about 3,500 Christmas meal baskets during the Christmas season.

For her part, Dearing expects Catholic Charities to see an increased demand at Christmas, noting that her organization has been getting requests since September.

While charitable organizations in the archdiocese have been asked to help more during the holiday season, they have seen increases throughout this year.

“If you talk with anybody, it’s not just this time of the year. It’s been throughout the year that you’ve seen an increase in request for assistance,” McNeil said. “The one thing is, around the holidays, it bears a bigger issue. It’s somewhat on the back burner the rest of the year.”

“The economy has adversely affected numerous families that have not been in this situation before, and that’s the concerning thing,” he added.