That Burger You're Eating Is Mostly Corn

David Biello  in Scientific American:

If you thought you were eating mostly grass-fed beef when you bit into a Big Mac, think again: The bulk of a fast-food hamburger from McDonald's, Burger King or Wendy's is made from cows that eat primarily corn, or so says a new study of the chemical composition of more than 480 fast-food burgers from across the nation. And it isn't only cows that are eating corn. There is also evidence of a corn diet in chicken sandwiches, and even French fries get a good slathering of the fat that makes them so tasty from being fried in corn oil. "Corn has been criticized as being unsustainable based on the unusual amount of fertilizer, water and machinery required to bring it to harvest," says geobiologist Hope Jahren of the University of Hawaii at Manoa's School of Ocean and Earth Science and Technology, who led the research. "We are getting a picture of the American diet on a national scale by using chemistry, which is quite objective."

Eating a diet of meat from corn-fed animals hasn't been linked to any specific health effects in humans. But it has resulted in widespread environmental degradation, including drained water supplies, degraded soils, and reliance on fossil fuels for fertilizer, pesticides and farm machinery fuel, says preventive medicine physician Bob Lawrence, director of the Center for a Livable Future at the Johns Hopkins Bloomberg School of Public Health, who was not involved in the study. It's also hard on cows, whose stomachs are specially designed to break down the cellulose in grass, leading to an epidemic of antibiotic use. Also, humans may lose out on beneficial omega-3 fatty acids—important for development of the nervous system and heart health—when they consume corn-fed as opposed to grass-fed beef.

More here.