Even deep in the US’s healthy eating heartland, it is clear how decades of farm subsidies have affected what America eats.

Last year at Google’s brand-new California headquarters, a wave of media interest surrounded the opening of Cafe 150, a restaurant offering fresh, healthy, high-quality food sourced from within a 150-mile radius. But just across Highway 101 in the affluent college town of Palo Alto is the Driftwood Deli, a roadside grocery and fresh-made sandwich store. Its $4 (€2.81, £1.96) lattes may come with a wrapper advertising The Economist magazine, but the displays of fresh fruit and nuts in the store are massively outweighed by racks of corn chips and popcorn, not to mention snack foods stuffed with the high-fructose corn syrup that is the sweetener of choice for America’s processed food.