The FAO reported lingering drought in the United States increased maize prices by 23 percent in July. The U.S. drought was the worst on record since the 1950s as temperatures reached record levels for most of the country.
Sugar prices increased by 12 percent because of unseasonable rains in Brazil, the largest sugar exporter, and grain prices rose 19 percent because of low production expectations from Russia.
Food prices had declined for the previous three months, the FAO said. For July, the monthly food price index was 6 percent higher than for June.
Kelly Wiesbrock, a manager at hedge fund Harvest Capital Strategies, said expectations for corn were exceptionally high for 2012.
"Then the month of June hit and into July, and it's just been a train wreck," she told Bloomberg News.
Record prices had pushed more than 40 million people in North Africa and the Middle East into extreme poverty.
The United Nations estimates more than 15 million people are facing food shortages and malnutrition due to a lingering drought. More than 200,000 children died of malnutrition last year and more than 1 million children are threatened.