Photo by Kris Krüg

(Updated below with Michael Pollan's response)

You want some petroleum with that Big Mac?

Journalist and food writer Michael Pollan broke down the hidden cost of America's best-known burger on Saturday to an eager audience at the Poptech conference. He traced the Big Mac's origins all the way back to the oil fields, used to make fertilizer that is crucial to the corn grown for cows in massive feeds lots.