November 13, 2008 – When you eat a burger and fries from a fast food restaurant, you're ultimately chowing down on corn. Researchers figured this out by going on a burger-buying spree
Researchers figured this out by going on a burger-buying spree,
collecting hamburgers, chicken sandwiches and French fries from the big
three fast-food chains around the country and doing chemical analyses
to find out the ultimate source of the animal meat and cooking oil that
go into those meals.
The findings, detailed in the Nov. 10 issue of the journal Proceedings of the National Academy of Sciences, showed that the cows and chickens that make up fast food sandwiches are fed almost exclusively corn and that French fries are almost universally cooked in corn oil.
Study leader Hope Jahren of the University of Hawaii said that the
work sheds light on corn's agro-economical importance as a source of
cheap feed, as well as the lack of transparency for the consumer as to
where their food ultimately comes from.
Fast food nation
Fast food chains make up more than half of all the restaurants in the
United States and sell more than $100 billion worth of food each year.
As meat consumption
has skyrocketed in recent years, so has fast food consumption and
associated health problems, such as diabetes and obesity. Just one
cheeseburger, one chicken sandwich or one small order of fries accounts
for 50 percent of a consumer's daily recommended calories, 80 percent
of carbohydrates, 75 percent of protein (90 percent for women) and a
full day's serving of fat.
All this makes fast food "a decent proportion of the American food supply," Jahren told LiveScience.
Fast food companies don't raise their food themselves, of course —
their meat and chicken are supplied by a chain of various distributors.
Conventionally raised cows and chicken are generally fed corn that has
been fermented into a delectable feed inside a silo — corn is cheap and
high in calories, meaning the animals get fatter faster (which means
faster revenue streams for cattlemen).
Jahren and her colleague Rebecca Kraft wanted to test fast food to
see if they could find corn's signature in the burgers and fries being
served across the country. Corn has a unique signature of carbon-13 (an
isotope of carbon, or form of the element with more or fewer neutrons
than is typical) that persists even when converted into an animal's
meat.
Burger samples
The researchers purchased fast food from McDonald's, Burger King and
Wendy's at three locations each in six major American cities: Los
Angeles, San Francisco, Denver, Detroit, Boston and Baltimore. At each
location, they bought three hamburgers, three chicken sandwiches and
three small orders of fries. (Jahren and Kraft did not receive any
outside funding for the study.)
Samples of the meat, chicken and fries were freeze-dried and then
blended up in a lab so that their carbon isotope signatures could be
analyzed.
Of the 160 samples of beef analyzed, 93 percent, or all but 12
samples, were from cows fed an exclusively corn-based diet, the results
showed. (The 12 differing samples all came from Burger King restaurants
along the West Coast.)
All of the chicken samples indicated an exclusively corn-fed diet
and were extremely homogeneous, meaning the meat from many chickens is
processed to make a chicken patty.
"How many animals does this thing contain?" Jahren said, adding that
the uniform carbon signature in the chicken "shows the extent to which
this thing is homogenized."
For French fries, Wendy's used a corn-based oil, while McDonald's and Burger King used other vegetable oils, the analysis revealed.
For Wendy's in particular, no item sampled could be traced back to a non-corn source.
"It all comes back to corn," Jahren said.
Implications
The problems inherent in corn-based food production don't necessarily stem from the nutritional content of corn itself.
"Corn has a reasonable place in the diets of animals and humans,"
said Marion Nestle, a professor of nutrition at New York University.
However, cows would not naturally eat corn, as they evolved to eat
and digest grasses. Farmers rely on corn because grasses are less
economical as a feed.
"From the standpoint of nutrition and the environment, feeding
cattle on grass would be ideal but even I don’t think that is entirely
practical," Nestle wrote LiveScience in an email.
The issue is complicated, Nestle said, because corn is highly
subsidized by the federal government and those subsidies make
"concentrated animal feeding operations" (called CAFO's) possible. In
CAFO's, animals are crowded together and allowed little movement; these
operations "have truly dreadful effects on the environments of the
communities in which they operate, are not healthy for animals, and
overuse antibiotics, which affects human health," Nestle wrote.
Jahren and Kraft also measured levels of nitrogen-15 in fast-food
samples, which indicated that the corn grown for feed and oil was heavily fertilized, which also can have significant local environmental impacts.
Lack of information
One point the study does highlight is the dearth of information on food production available to the consumer.
"I think the point the authors are trying to make is that most people
aren’t aware of the extent to which corn ingredients permeate the food
supply," Nestle wrote. "I do think that many people would like to know
more about where food and food ingredients come from."
Jahren contacted all three fast food companies and combed their Web
sites for information tracing the chain of supply of their products
because she wanted to compare the results of her study to the company's
sourcing information.
"None of this information is available to the consumer," Jahren said.
Wendy's spokesman Bob Bertini told LiveScience that "we
can't speak to the merits of the study," but added that "Wendy's does
not own, raise, transport or process livestock. However, we are
committed to the humane treatment of animals by our suppliers. We've
worked for many years with Dr. Temple Grandin, one of the world's
leading animal welfare experts, to strengthen our beef, pork and
chicken welfare programs."
McDonald's referred LiveScience to the American Meat Institute for comment.
An AMI statement on the study disputed the need for additional
consumer information on the sourcing of fast food products, noting that
consumers "appear satisfied with the current nutrition and ingredient
information available upon request or on signage in restaurants."
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