Rising Food Prices May Give Central Bankers Heartburn

Rising prices for food, from yogurt in the U.S. to steak in South Africa, are causing heartburn at the world's most powerful central banks.  ``We are sitting on structural changes that will affect agricultural prices for a long time to come,'' Paul Polman, chief financial officer of Vevey, Switzerland-based Nestle SA, the world's largest food company, said last month.