Amid rising food costs, the nation's restaurant owners saw an upturn in customer traffic last month following record lows in March, according to the National Restaurant Association.

The Washington-based trade group's monthly restaurant performance index rose by 0.4 percent in April to 98.4, with more owners reporting year-to-year sales gains and increased capital spending. Despite the gains, overall sales last month declined for the fifth time in the past six months.

The number of owners anticipating lower annual sales also shrank in April, though fewer expected economic conditions to improve by the end of the year, the trade group said.

"The sluggish economy and rising food costs continue to create a challenging business environment for restaurant operators," Hudson Riehle, the group's senior vice president of research, said in a statement.