Here is a sign of how shaky the economy is becoming: Wal-Mart says its shoppers are redeeming their holiday gift cards for basic items  pasta sauce, diapers, laundry detergent  rather than iPods and DVDs.

Merchants had hoped that shoppers with gift cards would provide a lift after a slack holiday season, partly because they tend to spend more than the value of the card. But that did not seem to happen last month, and retailers are feeling the pain.

On Thursday, the nation’s retailers turned in their worst January in almost four decades as high gasoline and food prices, the slumping housing market, tighter credit and tougher job prospects pushed some consumers to the edge.

Sales at 43 retailers surveyed by the UBS-International Council of Shopping Centers rose just 0.5 percent in January, well below a forecast of 1.5 percent.