New Delhi, July 14 -- WASHINGTON - The routine of the American grocery run has, for millions of families, become a calculation of monthly interest payments. More than a quarter of working-age Americans who use a credit card to buy groceries either cannot afford to pay the balance in full or have missed a minimum payment within the past year, according to new research from the Urban Institute, reported this week by CBS MoneyWatch.

The finding arrives five years into a period of food price inflation that has pushed grocery costs up 32 percent nationally, a sustained surge that has outpaced wage growth for most households and depleted the financial cushion that many families once kept in reserve for exactly this kind of emergency.

Kassandr...