U.S. producer prices were unchanged last month as the biggest decline in wholesale food costs in more than three years helped to keep a lid on inflation.

The Labor Department says its producer price index, which measures cost pressures before they reach the consumer, was flat in August after a 0.4 percent decline in July which was the biggest drop in 10 months. Food prices at the wholesale level fell 1.6 percent in August, the largest drop since a similar decline in April 2013.

Core inflation, which excludes the volatile energy and food categories, showed a modest gain of 0.1 percent. Over the past year, wholesale prices have been flat while core wholesale prices are up 1 percent, further evidence that inflation remains a no-show for the U.S. economy.